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Floral senescence or petal abscission that determine cut flower quality and longevity are primarily caused by the regulation of endogenous ethylene and perception of endogenous and exogenous ethylene in floral organs (such as the petals and gynoecium), in ethylene-sensitive species. Several attempts have been made to prolong flower quality and longevity using silver ions and other chemicals that inhibit ethylene production and perception in floral organs. Among the available compounds, 1-methylcyclopropene (1-MCP) has been increasingly used as ethylene-action/perception inhibitor because of its ability to inhibit ethylene action/perception and it is environmentally safe. Although 1-MCP has been used in several cut flower crops for about 25 years, there has been no review yet that critically emphasizes the benefits or difficulties of using this compound for the prolongation of cut flower quality and longevity. Here, we outline the role of 1-MCP in inhibiting ethylene action/perception and petal senescence in cut flowers through the blocking of receptor binding sites, and we discuss how various factors affecting efficacy of 1-MCP (such as concentration, treatment time and temperature, genotype, and flower stage) are involved in the achievement of flower longevity. Moreover, we highlight the advantages of applying nonvolatile and liquid 1-MCP formulation types, as opposed to using the conventional 1-MCP treatment (powder formulation type). We expect that this review will provide useful information for the future utilization of 1-MCP for the maintenance of cut flower longevity.

Pod shattering causes severe yield loss in rapeseed (Brassica napus L.) under modern agricultural practice. Identification of highly shatter-resistant germplasm is desirable for the development of rapeseed cultivars for mechanical harvesting. In the present study, an elite line OR88 with strong shatter resistance and a lignified-layer bridge (LLB) structure was identified. The LLB structure was unique to OR88 and co-segregated with high pod-shatter resistance. The LLB structure is differentiated at stage 12 of gynoecium development without any gynoecium defects. Genetic analysis showed that LLB is controlled by a single recessive gene. By BSA-Seq and map-based cloning, the resistance gene location was delimited to a 0.688 Mb region on chromosome C09. Transcriptome analysis suggested BnTCP8.C09 as the gene responsible for LLB. The expression of BnTCP.C09 was strongly downregulated in OR88, suppressing cell proliferation in the pod valve margin. KASP markers linked to the candidate gene were developed. This pod shatter-resistant line could be used in rapeseed breeding programs by direct transfer of the gene with the assistance of the DNA markers.

Chimonanthus praecox is an important ornamental plant and cut flower material in China. It blooms in the freezing winter and its flower emits charming fragrance. However, in different region the flowering time is variable. In order to understand the flowering mechanism of Ch. praecox in the winter, we studied the flower bud differentiation in Spring City-Kunming using paraffin sectioning method in the present study. Meanwhile we compared the differentiation process difference from different regions. It was found that the temperature is the key factor for its flower bud differentiation and blossom of Ch. praecox. In the process of bud differentiation, the temperature 20 °C was the optimum for inducing changes from vegetative axillary buds to reproductive buds and subsequent morphological differentiation in Ch. praecox. Furthermore in the first three differentiation periods—tepal primordial stage, staminal primordial stage and pistil primordial stage, Kunming took the shortest time to finish the process due to very rapid temperature rise to 20 °C, whereas, in Zhengzhou the time for these differentiations was the longest, which may be caused by the slow temperature rise. After May, the high temperature stress forced the flower buds into the first long dormant period in all regions except Kunming. In Kunming, the average temperature was only 20–25 °C, so the flower bud continued to differentiate. In all regions, Kunming is the first to complete whole flower bud differentiation even on the early August, and started the second dormancy very early but very long. In the other regions, the plants went through a shorter dormancy and the low temperature broke the dormancy rapidly. Contrarily the plants of Kunming spent a longer period for the low temperature. Thus, the low temperature less than 10 °C is a key factor to breaking the second dormancy. Surely the regular effects of temperature on flower bud differentiation and blossom is very helpful for florescence regulation of Ch. praecox.

Flowers' fungal and bacterial communities can exert great impacts on host plant wellness and reproductive success-both directly and indirectly through species interactions. However, information about community structure and co-occurrence patterns in floral microbiome remains scarce. Here, using culture-independent methods, we investigated fungal and bacterial communities associated with stamens and pistils of four plant species (Scaevola taccada, Ipomoea cairica, Ipomoea pes-caprae, and Mussaenda kwangtungensis) growing together under the same environment conditions in an island located in South China. Plant species identity significantly influenced community composition of floral fungi but not bacteria. Stamen and pistil microbiomes did not differ in community composition, but differed in co-occurrence network topological features. Compared with the stamen network, pistil counterpart had fewer links between bacteria and fungi and showed more modular but less concentrated and connected structure. In addition, degree distribution of microbial network in each host species and each microhabitat (stamen or pistil) followed a significant power-law pattern. These results enhance our understanding in the assembly principles and ecological interactions of floral microbial communities.

SummaryIn angiosperms, the process of pollination relies on species-specific interaction and signaling between the male (pollen) and female (pistil) counterparts where the interplay between several pollen and stigma proteins decides the fate of the pollen. In Brassicaceae, the dry stigmatic papillary cells control pollen germination by releasing resources only to compatible pollen thereby allowing pollen to hydrate and germinate. Despite the identification of a number of stigmatic proteins that facilitate pollination responses, the signaling mechanisms that regulate functions of these proteins have remained unknown. Here we show that, in Arabidopsis, an extremely functionally redundant mitogen-activated protein kinase (MAPK) cascade is required for maintaining stigma receptivity to accept compatible pollen. Our genetic analyses demonstrate that in stigmas, five MAPK kinases (MKKs), MKK1/2/3/7/9 are required to transmit upstream signals to two MPKs, MPK3/4, to mediate compatible pollination. Compromised functions of these fiveMKKsin the quintuple mutant (mkk1/2/3RNAi/mkk7/9) phenocopied pollination defects observed in thempk4RNAi/mpk3double mutant. We further show that this MAPK nexus converges on Exo70A1, a previously identified stigmatic compatibility factor essential for pollination. Given that pollination is the crucial initial step during plant reproduction, understanding the mechanisms that govern successful pollination could lead to development of strategies to improve crop yield.

Resource allocation to female and male function may vary among individual plants in species with variable sex expression. Size-dependent sex allocation has been proposed in hermaphrodites, in which female-biased allocation may increase with plant size. In many hermaphrodites with large floral displays, however, later-produced flowers tend to be functionally male. This paradoxical relationship between female and male function and plant size remains poorly understood. The subalpine lily Lilium lankongense has individuals of three sexual types: males with only staminate flowers, hermaphrodites with only perfect flowers, and andromonoecious plants with both perfect and staminate flowers. Here we tested theoretical predictions of size-dependent sex allocation in L. lankongense by measuring plant height and flower number of individuals of each sex at five field sites in the mountainous region of Shangri-La, southwestern China. To investigate variation in phenotypic gender, we identified sex expression of 457 individuals one year later. Our investigation showed that male plants, which usually produced one flower, were significantly smaller than andromonoecious and hermaphrodite plants. In addition, the total flower numbers of andromonoecious and hermaphrodite plants increased significantly with plant size. Large individuals were more likely to produce terminal staminate flowers, as there were more flowers in andromonoecious than in hermaphrodite individuals. Non-flowered plants were significantly smaller than flowering ones. Perfect flowers had significantly larger petals and pistils than staminate flowers, but they did not differ in dry weight of stamens. Our findings indicate that when plants are small, the less costly sex is favored, consistent with the ‘size-advantage hypothesis’. When plants are large, both female and male investments change isometrically, as later-produced flowers tend to be functionally male.

Background APETALA3 (AP3) has significant roles in petal and stamen development in accordance with the classical ABC model. Results The AP3 homolog, CDM19, from Chrysanthemum morifolium cv. Jinba was cloned and sequenced. Sequence and phylogenetic analyses revealed that CDM19 is of DEF/AP3 lineage possessing the characteristic MIKC-type II structure. Expression analysis showed that CDM19 was transcribed in petals and stamens of ray and disc florets with weak expression in the carpels. Ectopic expression of CDM19 in Arabidopsis wild-type background altered carpel development resulting in multi-carpel siliques. CDM19 could only partially rescue the Arabidopsis ap3‐–3 mutant. Conclusions Our results suggest that CDM19 may partially be involved in petal and stamen development in addition to having novel function in carpel development. How to cite: Githeng’u SK, Ding L, Zhao K, et al. Ectopic expression of Chrysanthemum CDM19 in Arabidopsis reveals a novel function in carpel development. Electron J Biotechnol 2020;45. https://doi.org/10.1016/j.ejbt.2020.03.001 .

Carpels, the female reproductive organs of flowering plants, are of major economic importance since much of our food is ultimately derived from carpel tissue and they are a defining innovation for flowering plants. Amazingly, little is known about the origin and conservation of the developmental program of the carpel besides the knowledge generated by utilizing Arabidopsis thaliana. However, in the past few years advances in ancestral state reconstruction, developmental genetics, and phylogenetic analyses led to advances in the field of flower evodevo. Here, I summarize recent work on ancestral state reconstructions of carpels, and the functions of the major components of the genetic networks governing carpel development described for Arabidopsis. Then, I point out how the stepwise addition of genes during land plant evolution has generated the A. thaliana carpel's developmental toolkit. By merging these observations, I propose a basic version of the ancestral angiosperm carpel developmental network.

The generic placement of two African species currently included in the genus Fimbristylis, F. hygrophila and F. variegata, has been contentious. These two species, which have been known for the past half century, are glabrous tufted perennials whose spikelets have semi-distichous to spiral glume arrangement, bisexual flowers, and a pistil with an enlarged and deciduous style base. While the two species fit the gross morphology of Fimbristylis, they differ in lacking the characteristic Kranz anatomy. We present phylogenetic inference of the Abildgaardieae based on DNA sequence data and map photosynthetic type. C4 photosynthesis has arisen twice in Abildgaardieae, in the Bulbostylis and the Fimbistylis clades, with a C3 clade (including Arthrostylis) sister to rest of tribe and a C3 grade (the two African Fimbristylis species, Trachystylis, Actinoschoenus) separating the two C4 clades. The new genus Zulustylis is described here, to segregate the two aberrant African Fimbristylis species, and its taxonomy presented.

Superoxide dismutases (SODs) are known as the first line of defense against reactive oxygen species (ROS). To better understand the regulatory effect of ethylene on programmed cell death and the molecular functions of SODs during the flower development, the expression patterns of RhMnSOD1, RhFeSOD1 and Cu/ Zn SOD1 genes, as well as the total SOD activities were compared in the two different roses, of ‘Marroussia’ and ‘Cool Water’ with long and short longevities, respectively. Total SOD activities were increased at the bud stage after 24 h of ethylene treatment also, H2O2 content increased at the bud stage at 48 h after the ethylene treatment in both cultivars. In most tissues, RhMnSOD1 and RhFeSOD1genes showed the highest levels of expression in the petals of ‘Marroussia’ and ‘Cool Water’ at both stages (bud and open stages) at 24 and 48 h after the ethylene treatment, respectively. Also, they displayed higher levels of expression in the gynoecium and stamen tissues of ‘Marroussia’ at the open stage at 48 h after the ethylene treatment. The results indicated that RhMnSOD1 is more sensitive to ethylene during flower senescence progression.

Phalaenopsis (Orchidaceae) is one of the most popular and trendy potted plants in the world. In order to achieve a better understanding of the influence of cold treatment to flowering, the morphological and hormonal changes were determined in three Phalaenopsis cultivars during flower bud differentiation and development. It was found that the three cultivars were all coordinated by the cold-induced release of reproductive bud dormancy, which was vernalisation pathway. The morphological development of flower bud differentiation was similar in Phalaenopsis cultivars: flower organ differentiation began with the formation of the outer petal primordia, followed by the inner petal primordia and finally, by the lip and column (stamen and carpel) primordia. The earlier the flower bud started differentiation, the earlier the flower bloomed. The timing of inflorescence primordium differentiation and flower bud development was controlled by plant hormones. It was found that ABA and GA3 levels of apical meristems of stalk before flower bud differentiation was high. High levels of IAA and ZR controlled the vegetative growth phase and the floral inductive phase, like the elongation of stalk.

Anther and gynoecium structure and embryological information in Koelreuteria and Sapindaceae as a whole remain understudied, as well as the evolution of imperfect flowers in the latter. The aims of this study were to analys in K. elegans subsp. formosana the anther and gynoecium structure and the development of male and female gametophytes in the two floral morphs of putatively imperfect flowers. Standard techniques were applied for LM and SEM. Compared to the normal anther development in staminate flowers, a delayed programmed cell death of tapetum, septum and middle layers on the onset of microspore stage result in indehiscent anthers in the functionally pistillate flowers. Orbicules are reported for the first time in Sapindaceae. Gynoecium development in functionally pistillate flowers is normal, whereas in functionally staminate ones a pistillode with degenerated ovules at the tetrad stage is formed. The pollen tube transmitting tract consists of one layer of epithelial cells with a small lumen in the style and ovary. The anatomy of the latter revealed an axile placentation and complete septum. Reproductive characters of Koelreuteria shared with other Sapindaceae taxa are a secretory binucleate tapetum, simultaneous cytokinesis, unicellular stigmatic papillae, Polygonum type megagametophyte with ephemeral antipodals, and ovules campylotropous, with funicular obturator and amphistomic micropyle. Imperfect flowers in the family are triggered by defective sporophytic tissues impacting on the normal development of microspores and megaspores, disrupting embryological events in staminate and pistillate organs at different developmental stages. Reconstructing ancestral character state under parsimony revealed that two ovules per locule, absence of obturator, presence of hypostase, and binucleate tapetum may be regarded as plesiomorphic for Sapindaceae. These analyses have provided information on the evolution of embryological characters in the family and its phylogenetic significance. Fil: Avalos, Adan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Zini, Lucia Melisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Ferrucci, María Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina Fil: Lattar, Elsa Clorinda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina

The success of fertilization depends on an array of complex physical and physiological interactions between the pollen and the pistil. To better understand the fertilization process in Malagasy baobabs, pistil structure and pollen tube growth were investigated in three species of Adansonia: A. grandidieri (section Brevitubae), A. madagascariensis and A. rubrostipa (Longitubae section). The pistil consists of an ovary with 6–9 locules, a very long hollow type style and six to nine lobed wet, papillate stigma. The pollen tubes grow in intercellular secretions in the stigma and join the stylar canal to reach the locule of the ovary and then the micropyle of the ovules. The size of the central stylar canal shrinks as it approaches the ovary. This restriction leads to gametophytic competition by reducing the number of pollen tubes that reach the ovules. The pollen tubes reach the ovules four to six days after pollination. The pollen tubes of the two Longitubae species grow faster than those of A. grandidieri. This information on the progamic phase of baobabs is essential to understand the mode of reproduction of baobabs.

Anthurium andraeanum is a high-grade potted flower that enjoys global popularity. Its floral organs have been substantially modified, and its ornamental value is based on its petaloid bracts. MADS-box gene products are important transcription factors that control plant development. In particular, the APETALA1 (AP1)/FRUITFULL (FUL) family of MADS-box genes plays a key role in flowering transitions and out-whorl floral organ identity specification. In this report, one FUL-like gene was cloned from Anthurium andraeanum and named AaFUL1 after bioinformatics identification. Subsequent subcellular localization experiments confirmed that the AaFUL1 protein was located in the nucleus, and data obtained from an expression analysis indicated that the relative expression level of AaFUL1 was the highest in bracts and inflorescences, while its expression was relatively low in stems and roots. Next, an AaFUL1 overexpression vector was constructed and ectopically expressed in tobacco. The transformants did not show any early flowering phenotype, but the average internode length of the inflorescence branch was significantly higher than that observed in the control, and its petal color had substantially faded. The morphology of the petal and pistil was clearly changed, the fruit was deformed, and the seed was largely aborted. These data indicate that even though the sequence of AaFUL1 is relatively conserved, its function differs from that of other orthologs, and the FUL subfamily of MADS-box transcription factors may have taken on new functions during the evolution processes. The results of this experiment enrich our knowledge of FUL transcription factors in monocotyledon plants.

The apricots growing in different environments face the risk of frost in spring months. There is limited information about how floral organ structures of apricots are protected from frost injury during late spring frosts. As a solution related this matter, the cell death points (CDPs) of some apricot flower organs (pedicel, receptacle, petal, stamen and pistil) at different development phases (first white, first bloom and full bloom) were described for the first time using differential thermal analysis under temperature-controlled, laboratory-based freeze assays. The CDPs were clearly identified for the different apricot cultivars that were evaluated during all blooming phase. In order, from the most sensitive flower organs to the least sensitive on average, were the receptacle, pedicel, petal, stamen and pistil organs. Moreover, a significant cultivar effect was found on freeze damage to most of the flower parts. Under laboratory-based freeze assays, the CDP initially occurred in the receptacle of the apricot flower and ranged from -1.9 to -11.7 °C. The pistil, the most tolerant flower organs, however, remained tolerant of low temperatures range of -6.6 to -17.0 °C, the lowest temperature tested in the research. Overall, flowering organs of ‘Erzincan Tokaloglu’ was the most sensitive to freezing, whereas flowering organs of ‘Igdir Salak’ and ‘Sekerpare’ were the most freezing-tolerant. The DTA assays indicated that the receptacles are much less frost resistant than other flower organs, and especially in contrast to pistils, are not cold tolerant. The CDP of floral organs in apricot is an effective mechanism that protects developing offspring from possible cold injury result of episodic late spring freezing events. In conclusion, cultivar variability effects on frost tolerance of open apricot flowers were defined, which can be exploited in breeding programs to improve the cold hardiness.

High temperature (HT) stress during flowering severely threatens crop grain yield, however, little is known about the underlying mechanisms in maize. A HT sensitive maize hybrid was subjected to 32/22 ℃ (maximum/minimum temperature, control), 36/26 ℃, and 40/30 ℃ for 14 consecutive days bracketing flowering (trial 1) and for seven days prior to flowering (trial 2). Maize grain yield did not decrease in the 36/26 ℃ treatment during trial 1 compared to the control treatment, but reduced by 73.6% in the 40/30 ℃ treatment as a result of reduced kernel number rather than kernel weight. High temperature stress advanced tasseling and pollen shedding, extended the anthesis-silking interval, and reduced the number and viability of pollen shed, but had no effects on silking. The shortened duration of pollen shedding was a result of the accelerated flowering speed of the tassel inflorescence. Leaf assimilate can be transferred to the tassel, but cannot be converted into starch in the HT stressed pollen. The damaged pollen morphology and the interrupted sugar to starch physiological process explained the reduced pollen viability. Starch granule number and size in the pollen decreased with the increased temperature. Thus, male organ growth is more sensitive to HT than female organs. Understanding the underlying mechanisms has implications for selecting or breeding HT tolerant maize.

Interspecific hybridization is often hindered by incompatibility reactions occurring at various stages of hybridization, from early pollination to initial growth and reproductive stages of the progeny. Characterization of reproductive barriers leads to further understanding of how each species recognizes its own identity and supports the development of methods to overcome the barrier and produce interspecific hybrids. We investigated interspecific cross-(in)compatibility among five species in Prunus (Rosaceae), namely P. armeniaca, P. avium, P. mume, P. persica and P. salicina. In vivo pollen tube growth tests showed the presence of a post-mating pre-zygotic barrier in many cross combinations. Irrespective of the crossing direction, reduced pollen tube growth was observed in interspecific hybridization with P. avium, a species phylogenetically remote from the other species. Different compatibility reactions in reciprocal crosses were observed in some interspecific hybridizations. P. persica as a pollen donor was compatible with P. mume and P. salicina, while the reciprocal cross was incompatible. Furthermore, P. salicina as a pistil parent accepted pollen from P. armeniaca, P. mume and P. persica, while P. salicina was cross-incompatible with those species in reciprocal crosses. These results suggest that not only the phylogenetic relationship but also other mechanisms may be involved in interspecific cross-(in)compatibility. Embryo rescue culture showed the presence of a post-zygotic barrier in the cross between P. mume as seed parent and P. persica as pollen parent. Factors affecting interspecific hybridization are discussed with special reference to genetic distance between parents and morphological characters such as pistil length.

In flowering plants, continuous cell-cell communication between the compatible male pollen grain/growing pollen tube and the female pistil is required for successful sexual reproduction. In Arabidopsis thaliana, the later stages of this dialogue are mediated by several peptide ligands and receptor kinases that guide pollen tubes to the ovules for the release of sperm cells. Despite a detailed understanding of these processes, a key gap remains on the nature of the regulators that function at the earlier stages. Here, we report on two groups of A. thaliana receptor kinases, the LRR-VIII-2 RK subclass and the SERKs, that function in the female reproductive tract to regulate the compatible pollen grains and early pollen tube growth, both essential steps for the downstream processes leading to fertilization. Multiple A. thaliana LRR-VIII-2 RK and SERK knockout mutant combinations were created, and several phenotypes were observed such as reduced wild-type pollen hydration and reduced pollen tube travel distances. As these mutant pistils displayed a wild-type morphology, the observed altered responses of the wild-type pollen are proposed to result from the loss of these receptor kinases leading to an impaired pollen-pistil dialogue at these early stages. Furthermore, using pollen from related Brassicaceae species, we also discovered that these receptor kinases are required in the female reproductive tract to establish a reproductive barrier to interspecies pollen. Thus, we propose that the LRR-VIII-2 RKs and the SERKs play a dual role in the preferential selection and promotion of intraspecies pollen over interspecies pollen.

‘Li Guang’ apricot, a famous local variety, originated in Dunhuang city, Gansu Province, China. The fruit quality of 'Li Guang' apricot is excellent and It will generate greater financial returns. However, due to the change of natural environment and planting structure, pistil abortion has become an important factor affecting fruit setting rate, yield and quality. It seriously affects the economic benefits of this geographical indication product.The distribution and regulation of hormones play an important role in signal molecules of flower abortion. In order to elucidate the key molecular mechanism of apricot flower hormone abortion. Using normal and abortive buds as materials, the pistil abortion of apricot was observed, and the genes related to flowering regulation were identified by RNA sequencing. As compared with normal flowers, the pistil appearance of abortive flower is normal, but the ovary development is abnormal. Microstructure showed that the pollen grains of abortive flowers were decreased sharply, the ovaries shrunk and the ovule primordia developed stagnately. The hormone levels of ZR, IAA and CTK in abortive flowers decreased significantly. But the content of ABA and GA was significantly higher than normal flowers. Through RNA-Seq, it revealed that AUX1, TIR1, ARF, GH3 and SAUR, vital genes displayed identical differential expression profiles to auxin transduction pathway, and ABF, SnRK2, PP2C to abscisic acid, JAZ, MYC2 to jasmonic acid. Mutations in ARF, which encodes auxin response factor, can lead to serious defects in pistils. ARF promotes ovary formation mainly by inhibiting the expression of SPT in this domain. AG regulates early pistil development through CTK-AUXIN, and directly or indirectly affects these hormone pathways at different levels. Once the pistil begins to develop, SPT and ind connect CTK and AUXIN to realize the development of pistil structure. Other factors affecting hormone transport also showed apical and basal hyperplasia and ovary development.

1-Aminocyclopropane-1-carboxylate (ACC) oxidase (ACO) catalyzes the final step of ethylene biosynthesis. ACO proteins are also reportedly encoded by a multigene family. Although the presence of several ACO genes is suggested in carnation (Dianthus caryophyllus L.), DcACO1 is the only ACO gene in which full-length cDNA has been isolated. This study aimed to clone another ACO gene in carnation flowers and investigate changes the expression of the two ACO genes in floral organs during flower senescence. We cloned a homolog of the ACO gene from carnation gynoecium and designated it DcACO2. Transcript levels of DcACO2 were higher in the style and ovary than in the petals at harvest, although DcACO2 transcript levels in these organs increased during flower senescence. The ACO activity in the style was very high at harvest, suggesting that this high activity could be attributed to the translation of the DcACO2 transcript. However, DcACO2 transcript was only detected at very low levels in the petals of senesced flowers. Ethylene and ACC treatments accelerated petal wilting and increased ethylene production of the petals, style, and ovary. In the style and ovary, the DcACO1 transcript level was markedly higher than the DcACO2 transcript level as a result of ethylene and ACC treatments, and DcACO1 transcript levels in the petals were also increased by ethylene and ACC treatments. These results indicate that the expression of DcACO1 and DcACO2 are differently regulated among floral organs during senescence in carnation flowers.

Berberis microphylla G. Forst. (calafate) is an evergreen and spiny shrub considered as a non-timber patagonian forest product, that is relevant for diversification of agrifood production, particularly interesting since its black–blue fruits are rich in phenolic compounds. The objective of this research is to analyze the variability in floral traits and reproductive success of Berberis microphylla G. Forst. among and within three populations of Tierra del Fuego along three growing seasons. The presence of variability in some floral traits as well as in the reproductive success of B. microphylla among and within three Tierra del Fuego populations was observed, in agreement with the environmental conditions i.e. mean daily temperatures and accumulated rainfall for the three populations and the three growing seasons. Flower dry weight and gynoecium area are good indicators of flower quality (i.e. ovule number), with positive and significant correlations between them (flower dry weight with gynoecium area, r = 0.551; p=

Every year tree fruit and grape growers suffer significant economic losses from cold damage to reproductive buds. A combination of pre-planned passive and active frost protection methods has been prevalently used to achieve some level of protection. Herein, we describe a new effective approach to protecting reproductive fruit buds from cold damage. Electrostatic application of cellulose nanocrystals (CNC) dispersion to fruit buds forms a thermal insulation layer with low thermal conductivity (0.061 W m−1 K−1). The dispersion was applied to dormant grapevine (Vitis vinifera) buds, and hardiness was evaluated by differential thermal analysis (DTA). CNC-treated buds were more resistant to freezing temperatures than untreated buds. Cold hardiness was improved by 2–4 °C with CNC treatment. The hardiness of sweet cherry (Prunus avium L.) reproductive buds at the ‘first white’ stage of development was also tested comparing CNC-treated (2% mass) and non-treated clusters. Pistil mortality was evaluated 24 h after treatment. Untreated pistils were killed at ca. −1 °C while the CNC-treated buds were hardy to ca. −4 °C. The temperature at which ca. 10%, 50%, or 90% of untreated pistils were killed was ca. −1.5 °C, −2.8 °C and −5.5 °C, the temperature at which ca. 10%, 50%, or 90% of treated pistils were killed was ca. −4.4 °C, −6.5 °C and −7.7 °C. In general, CNC treatment improved cold-hardiness of grape and sweet cherry buds by about 2–4 °C. These results demonstrate great potential for field applications of CNC to improve speciality crop yield security by protecting reproductive buds from cold damage.

Most Passiflora species present self-incompatibility and thus depend on cross-pollination for fruit production. Therefore, the objective of this work was to evaluate the floral and reproductive biology of 17 Passiflora species, through pollen viability, stigma receptivity, fruit and seed set formation, as well as the pollen-pistil interaction in three floral development stages (pre-anthesis, anthesis and post-anthesis), seeking to maximize the efficiency of controlled pollinations. Pollen viability was estimated by in vitro pollen germination, fluorochromatic reaction and Alexander’s solution, as well as fruiting and pollen-pistil interaction. The stigma receptivity was determined in alpha-naphthyl acetate. The highest percentages of pollen viability, stigma receptivity, fruit and seed set were observed during floral anthesis for all Passiflora species studied, while the lowest values were observed in pre-anthesis. The species P. rubra L. presented the highest percentages of in vitro pollen germination, viability with FDA, stigma receptivity, pollen/pistil compatibility, and high fruit set in anthesis. In contrast, the lowest values of these traits were observed in P. galbana L. The results obtained can support the selection of genetic material and allow inferences about the best pollen collection moment and the peak stigma receptivity to maximize the chances of pollen germination and consequently increase the efficiency of controlled pollinations for both agronomic and ornamental purposes.

The floral anatomical structural and developmental features of seeds and fruits of quinoa (Chenpodium quinoa Willd) cv. Hualhuas were studied using light microscope with the purpose to elucidate their structure and to contribute ecological studies of the species. The plants produce panicle inflorescences having hermaphrodite and pistillate flowers. The hermaphrodite flower possesses: 5 imbricate sepals; 5 antisepalous stamens; its filaments extend laterally forming a ring of nectariferous tissue surrounding the ovary having modified stomata. The gynoecium is bicarpellate with unilocular ovary having a single campylotropus ovule. The basal part of the ovary contains two dorsal carpellary bundles one is small towards the posterior side the other is large towards the anterior side. Whereas the ventral carpellary bundles of the two carpels occurring in the center of the ovary base and consist the vascular supply of the ovule. The dorsal posterior bundle terminates with the appearance of the locule. The ovule attach with the basal placenta on the anterior side of the ovary. The posterior carpel is sterile and reduced whereas the anterior one is fertile. The nutrients movement into the seed takes place through the high selectivity phloem elements embedded in the vascular strand of the funiculus. The collapsed outer layer of the pericarp in mature fruit could reshaped and regain turgor pressure after soaking in water, this may help for rapid germination. Although quinoa has thin seed coat layers however it have thick cell walls could maintain the moisture of embryo and perisperm and increase seed hardness as response to the arid habitats. Keywords: Embryogenesis, Floral anatomy, Fruit setting, Gynoecium, Vascular system

Heterostyly is a reproductive system in which plant populations comprise two or three morphs with different lengths of pistil and stamen. In the present study, we demonstrated clear morphological traits of Persicaria odorata subsp. conspicua, a distylous taxon. Like other distylous species, the length of the style and filament are different between the two morphs. Although the fruit size and rate of pollen viability are slightly different between the two morphs, these two morphs have functionally hermaphroditic flowers based on production of pollen and fruits. The stigma length, anther length, ovary size, and fruit size are significantly larger in pin-type flowers than in thrum-type flowers, but the diameter of the pollen and aperture are larger in thrum-type flowers than in pin-type flowers. The tepal size is larger in pin-type flowers although not significantly. However, except for these reproductive organs, we could not detect any morphological differences between the two morphs, including the tepal and leaf microstructures. We further compared the detailed morphology of the two morphs and discussed the significance of heterostyly in P. odorata subsp. conspicua.

Abelia tyaihyoni is a Korean endemic species and also designated as an endangered taxon in the IUCN Red List. We present a comprehensive embryology of A. tyaihyoni, comparing it with previously available information on the Caprifoliaceae and related families, and identifying possible evolutionary trends. Overall, comparisons showed that Abelia is similar to the other genera of Caprifoliaceae in many embryological features, including the tetrasporangiate anther, the anther wall, dicotyledonous wall formation, fibrous endothecium, simultaneous cytokinesis, tetrahedral tetrads, and three-celled pollen grains. In addition, Abelia share anatropous, unitegmic, and tenuinucellate ovules, ephemeral antipodals, and a cellular-type endosperm with many caprifoliaceous genera. Some embryological features, such as the amoeboid tapetum with several nuclei forming a polyploid mass, bisporic Allium-type embryo sac, obturator, bilayered endocarp, and compressed exotesta, are here described for the first time in this genus. The results confirm that A. tyaihyoni shares some significant embryological features with other Caprifoliaceae. Although previous embryological studies on the Caprifoliaceae lack convincing evolutionary explanations, our comparative approach demonstrates some possible apomorphies in Abelia such as the presence of two sterile carpels, bisporic Allium-type embryo sac, single-seeded fruit, bilayered and sclerified endocarp, and compressed exotesta.

A new fossil flower preserved in amber from Miocene sediments of Simojovel de Allende, Mexico, is described and recognized as a new member of Celastraceae. This fossil flower is bisexual, with a 5-merous perianth and extrastaminal disk, furthermore the presence of two stamens inserted in the inside surface of a pentagonal disk and ovoid pistil constitute characters that allows its inclusion in Salacia (Salacioideae). This is a new extinct taxon and represents a Salacia species with a mosaic of characters today present in different extant species distributed along the Paleo and Neotropic. The presence of Salacia ca. 23–15 My in southern Mexico can be explained through the Boreotropical Flora Hypothesis, a proposal supported by the Paleogene fossil record of Celastraceae in high latitude North America. The neobotanical data suggest that the Salacioideae was derived from an independent Old World Celastraceae lineage, and subsequently diversified in the New World. Fossil and extant plant evidence support the importance of fossil plants collected in low latitude North America and highlight the relevance of paleobotanical studies in challenging biogeographical hypothesis.

The characterization of flower specific promoter is critical during flower development by cucumber transformation technology. AGAMOUS (AG) is an organ identity gene that is required for carpel and stamen development in Arabidopsis. The promoter and second intron of AG contain multiple regulatory elements that confer proper spatial and temporal expression. Cucumber is an important vegetable with unisexual flowers. Cucumber MADS-box 1 (CUM1) is the AG homolog in cucumber, belonging to the euAG lineage along with AG. In situ hybridization showed that CUM1 was specifically expressed in the stamens and carpels of cucumber. GUS staining indicated that the second intron of CUM1 confers stamen-specific expression, while the promoter of CUM1 drives both stamen- and carpel-specific expression during the early stages of flower development, but is restricted to carpel- and connectivum-specific expression during the late stages of flower development. Furthermore, a yeast one-hybrid assay demonstrated that two auxin response factors (CsARF13 and CsARF17) had bound directly to the second intron of CUM1. Our data suggest that different regulatory circuits operate in AG homologs in plant species with distinct sex types. Keywords: cucumber, CUM1, promoter, intron, in situ hybridization, GUS staining, yeast one-hybrid

Philodendron flowers are numerous, small, unisexual or sterile, without perianth and exclusively pollinated by beetles, representing an Angiosperm-ancient pollination syndrome. Species of the genus are traditionally classified under three subgenera, P. subgenus Philodendron, P. subgenus Meconostigma, and P. subgenus Pteromischum. In recent phylogenetic analyses, two main lineages of Philodendron were recovered, Meconostigma and a Pteromischum + Philodendron lineage. Although a modest advance in the knowledge of the evolutionary history of the genus has been made, little attention has been paid to floral morphology in this group, in particular to structural studies on flowers of P . subg. Pteromischum in light of pollination biology. Our aims were (i) to investigate the flower structure of P. propinquum ( P . subg. Pteromischum ) through light and scanning electron microscopy and histochemistry; and (ii) to compare relevant floral characters among the three subgenera. Flowers of P. propinquum , which is endemic to the Atlantic Forest, are described for the first time. The pistillate flower presents a shallow, broad compitum, and a large number of ovules per locule; pistillate and staminate flowers present subepidermal druses; sterile units present raphids and starch grains; the papillose epidermal cells from sterile units and staminate flowers present terpene contents and stomata, probably representing diffuse osmophores. Our analysis suggests that the balance between pollen uptake (stylar lobes) and accessibility to the locules (stylar canals and compitum) were decisive to drive gynoecium evolution of the Philodendron genus. The presence and location of druses and raphides in stamen and gynoecium indicate a protective function against florivores.

CMS, which refers to the inability to generate functional pollen grains while still producing a normal gynoecium, has been widely used for pepper hybrid seed production. Pepper line 8214A is an excellent CMS line exhibiting 100% male sterility and superior economic characteristics. A TUNEL assay revealed the nuclear DNA is damaged in 8214A PMCs during meiosis. TEM images indicated that the 8214A PMCs exhibited asynchronous meiosis after prophase I, and some PMCs degraded prematurely with morphological features typical of PCD. Additionally, at the end of meiosis, the 8214A PMCs formed abnormal non-tetrahedral tetrads that degraded in situ. To identify the genes involved in the pollen abortion of line 8214A, the transcriptional profiles of the 8214A and the 8214B anthers (i.e., from the fertile maintainer line) during meiosis were analyzed using an RNA-seq approach. A total of 1355 genes were determined to be differentially expressed, including 424 and 931 up- and down- regulated genes, respectively, in the 8214A anthers during meiosis relative to the expression levels in the 8214B. The expression levels of ubiquitin ligase and cell cycle-related genes were apparently down-regulated, while the expression of methyltransferase genes was up-regulated in the 8214A anthers during meiosis, which likely contributed to the PCD of these PMCs during meiosis. Thus, our results may be useful for revealing the molecular mechanism regulating the pollen abortion of CMS pepper.

Jasmine (Jasminum sambac Aiton, Oleaceae) flowers are widely consumed in many countries for their tea-making, medicinal and ornamental properties. To improve the quality and yield of flowers, it is very important to carry out cross-breeding between different petal types of jasmine. However, because of the difficulty of sexual reproduction, there is no report on the success of jasmine crosses. In this paper, single- and double-petal jasmine plants were crossed artificially. The stigmas of single-petal plants post pollination, including those at 0 h after pollination (CK), 1 h after pollination (T1) and 6 h after pollination (T2), were sequenced by transcriptomic combined with proteomic analyses. A total of 178,098 gene products were assembled. Simultaneously, a total of 2337 protein species were identified. Some regulatory gene products and functional protein species were identified that may be involved in the process of pollen-pistil interactions. These findings suggest that the identified differentially expressed gene products and differentially accumulated protein species may play vital roles in jasmine plants in response to pollen-pistil interactions, providing important genetic resources for further functional dissection of the molecular mechanisms of these interactions. Significance These results have important scientific significance to take effective measures to overcome pre-fertilization barriers and to guide the cross breeding of jasmine. Further, they can also be used for reference in other plant breeding with the same fertilization barriers.

Fruit is a specific organ of angiosperms that develops from ovary or other parts of flower after the pistil is pollinated and fertilized. Fruit size is a key indicator of fruit yield and quality, and an adaptive feature of evolution in horticultural plants which are becoming increasingly important for human life. Unveiling the molecular pathways that regulate fruit size development has both scientific and economic significance. The final size of fruit relies on the coordinated control of cell division and cell expansion. Several molecular mechanisms are involved in the determination of fruit size, including hormonal regulation (IAA, GA, CK, ABA, ETH and BRs), CLV-WUS signaling pathway, MADS-box family, ubiquitin-proteasome pathway, quantitative trait loci (QTLs), MicroRNA and endoreduplication. This review describes the current findings on regulation mechanisms of fruit size development in horticultural plants, and the prospects for studying fruit size development are also discussed.

The plant ovule is a fundamentally important organ that is the direct progenitor of the seed. It is one of the last structures to form in the flower and contains relatively few tissues, but undergoes complex developmental transitions that are essential for reproduction. Ovule number and flower fertility are important factors influencing yield, yet studies have identified challenges in trying to increase one without compromising the other. Recent findings in Arabidopsis and cereal crops highlight regulatory pathways that contribute to this yield constraint. Here, we consider the basis for variation in ovule number and development, with a particular focus on hormones and transcriptional regulators that constitute promising targets for the optimisation of reproductive traits and yield.

Passiflora incarnata is a functionally andromonoecious clonal wildflower, native to the southeastern United States, whose primary pollinator is the carpenter bee, Xylocopa virginica. While recent studies looking at reproductive ecology in P. incarnata have classified flowers as one of two morphs (male or hermaphroditic) based on stylar deflexion, preliminary field studies conducted in Tennessee indicated there were five distinct morphs present (three male, two hermaphroditic), supported by stylar deflexion, floral size, and pistil development. The present study sought to test the hypothesis that five distinct floral morphs are present in P. incarnata by sampling 13 floral characters, and to document variation in nectar constituents, volume, and concentration across the five morphs. Five well-established individual plants were examined at three sites in Cookeville, Tennessee. Two-factor permuted analysis of variance of 13 floral characteristics with floral morph and individual plants as factors suggested that morph:plant interactions explained 6%, individual plant explained 18%, and floral morph explained 36% of variation in floral characteristics. Nectar sampling indicated that all morphs produced nectar comprised exclusively of sucrose. Nectar volume generally increased with floral morph size, while nectar concentration decreased. NMDS analysis indicated that four of the five hypothesized morphs were supported as distinct, with morphs 4a and 4b best classified as submorphs due to substantial overlap. The supported morphs are best distinguished by ovary width, ovary length, style length, and stigma width. These findings support a hypothesis that the morphs result from variation in developmental arrest during floral ontogeny. The ecological implications of the morphs and nectar variation are considered for X. virginica with suggestions for additional studies.

New Normapolles reproductive structures are described from several Late Cretaceous stratigraphic horizons of central and western Europe: the Klikov Formation (late Turonian–Santonian), the Aachen Formation (Santonian) and the Walbeck Formation (Maastrichtian). They are assigned to a new genus, Zlivifructus , containing three new species, Zlivifructus vachae , Zlivifructus sklenarii and Zlivifructus sp. The new genus is based on several small flowers/fruits. The flowers are bisexual, bisymmetrical and have an inferior ovary with a hypanthium. The tepals are attached on top of the hypanthium. The genus has four tepals, in two decussate pairs. The androecium consists of four stamens. The gynoecium is bicarpellate, with a unilocular ovary and two styles. Fruits are nuts with a single erect, orthotropous seed. Zlivifructus is separated from Caryanthus based on the presence of four stamens. Both bear pollen grains of the Normapolles group. Organization of the flowers/fruits in Zlivifructus , as well as the structure of the pollen indicate that this new Normapolles flower is of core fagalean affinity. The new genus is closely related to other Normapolles genera, particularly Caryanthus , and may be close to the base of the Juglandaceae-Rhoipteleaceae clade.

Studies on breeding systems and flower morphology are valuable to infer how environmental factors impose evolutionary change in plants. This study focused on the characterization of floral morphs and reproductive systems in Pachycereus pringlei and how this iconic columnar cactus might be a useful genus to understand the evolution of these highly variable structures. We determined breeding systems, characterized floral morphs in five genetic populations, and used pollen:ovule ratios and stamen-stigma distance to verify the sexual system in bisexual flowers. Our inquiries provide insights into the factors driving intra-specific disparity in flower attributes and the reproductive versatility in P. pringlei . Foremost, the lability of breeding systems is expressed primarily as gynodioecy in the North, trioecy in the South, mainly dioecy in CBS, and hermaphroditic in Catalana and Cerralvo Islands. A latitudinal trend in ovule production, dimensions in gynoecium, androecium, and floral display characters is consistent with a northward increase in vegetative traits suggesting physiological responses to the environmental variation characterizing the Baja California Peninsula (BCP). Also, nectary size decreases northwards in staminate flower, but these flowers are larger in the CBS and South populations suggesting sex-specific selection, e.g., pollinator-driven, acting in different magnitudes on sexual attributes of floral morphs and populations. The presence of rudimentary structures of the dysfunctional sex support the hypothesis of the evolution of unisexuality from an early bisexual ancestor. In conclusion, this investigation provides insights into the factors driving intra-specific disparity in flower attributes and the reproductive versatility in P. pringlei to replace ancestral conditions, specifically the substitution of the hermaphrodite phase with dioecious, gynodioecious, and trioecious breeding systems throughout mainland BCP and Sonora. We posit that the biogeographic patterns of breeding systems and floral traits of this emblematic cactus resulted from the interaction of past factors (northwards range expansion) and contemporary biotic and abiotic factors.

Acer elegantulum is morphologically andromonoecious, and hermaphrodite flowers are protogynous. 25.73% of flowers studied were hermaphrodite, and these did not differ in petal length, petal width or flower diameter from staminate flowers, though the lengths of anthers, filaments, styles and ovaries differed significantly. Staminate flowers are functionally male; their staminate flowers developed, dehisced and shed normally, but their ovules and ovaries degenerated gradually at the megasporogenesis stage, and the mature ovaries contained only aborted ovules. Surprisingly, however, despite developing normally until tapetum formation, the anthers of hermaphrodite flowers failed to dehisce when mature, despite developing normally through tapetum formation and dissolution; these flowers’ pistil primordia developed normally, finally forming eight-nucleic embryo sacs. The morphologically hermaphrodite flowers of A. elegantulum are therefore functionally female, and the species is functionally monoecious. We discuss the evolution of staminate and hermaphrodite flowers and suggest that both evolved from ancestrally hermaphrodite flowers, by complete abortion of the pistil or incomplete and late-stage stamen abortion.

Multicellular organisms rely on the activity of organs that develop to a specific size and shape and are patterned into particular tissues. One of the most complicated plant structures is the female reproductive organ, the gynoecium, which must integrate a range of developmental cues to ensure efficient reproduction. Here we review recent discoveries on gene networks and hormonal activities that are required to (1) control cell division, (2) pattern the gynoecium along polarity axes and (3) specify organ shape and seed dispersal. Comparisons are made to other plant organs to understand how a developmental programme, which is evolutionarily derived from the formation of leaves, has been recruited and modified to create a reproductive machinery that has allowed angiosperms to dominate the world.

The internal morphology and anatomy of silicified fruits of Fontainocarpa were studied using traditional thin sectioning techniques, SEM and synchrotron computed tomographic (CT) imaging and animations, to enable comparative analyses with extant, indehiscent-fruited genera in the Euphorbiaceae including Fontainea, Aleurites and Hylandia from Australia, and other non-Australian crotonoid genera. Thin sections and sectioning show that the fruits of Fontainocarpa are indehiscent, multicarpellate and usually 3- to 5-loculate, with axial placentation, a single ovule per carpel and the ovules are anatropous and have antitropous curvature. A ventral vascular trace that supplies each ovule is embedded in the bitegmic seed coat. The internal anatomy is therefore consistent with the Euphorbiaceae. Additional characters, including indehiscent fruits, distinctive vascular channels (foramina) that penetrate through the fruit wall into the locule, and thin membranous seed coats are restricted to very few genera in the Euphorbiaceae, but occur together in extant Fontainea. The seed coat in extant Fontainea and fossil Fontainocarpa seeds is membranous, and appears to lack the palisadal exotegmen of most genera in the Euphorbiaceae. Fontainocarpa fruits were compared with those of extant Fontainea and the fossil has a combination of features unlike those of extant taxa. It shares with Fontainea picrosperma in having endocarps with convex intersutural surfaces lacking ornamentation and a similar number of locules and with Fontaineavenosa in having conspicuous foramina. This study therefore supports a close relationship between Fontainea and Fontainocarpa and is further evidence of the Crotonoideae in the fossil record in Australia, and is one of the few records of this subfamily worldwide. This study is one of the few, to date, using synchrotron CT imaging to reveal the internal morphology of silicified fruits and to utilize animations to examine the structure of these fruits.

The fungus Monilinia vaccinii-corymbosi infects open blueberry flowers via stigma and style, causing mummy berry disease. Management of flower infection in this pathosystem relies on multiple fungicide applications during bloom. However, flowers that open between spray applications may remain prone to infection because the stigmatic surface (infection court) is not exposed to active ingredient, unless there is systemic movement in the pistil and/or eradicant activity in the ovary. To quantify and compare pre- and post-infection fungicidal activity in flowers, we examine here the ability of two systemic fungicides to prevent flower infection and subsequent fruit colonization by M. vaccinii-corymbosi . The fungicides were applied before or after anthesis (first day of open bloom) in an experimental system where flower development stages and inoculation timing were monitored and controlled precisely. In greenhouse experiments with potted rabbiteye blueberry plants, treatment with fenbuconazole, triforine, or water was made when sufficient numbers of flower clusters at anthesis and earlier pre-anthesis stages were present simultaneously. Treated flowers ( n = 10,992) were tagged, observed daily, and individual flowers were pollinated and inoculated 1 day after opening. Fruit from treated flowers were assessed for incidence and severity of mummification. Both fungicides provided excellent protection to newly opened flowers that were at the anthesis stage during fungicide application, but differed in their activity in unopened flowers at pre-anthesis stages during application. Fenbuconazole suppressed infection in unopened flowers that were on average 2.5 days pre-anthesis at the time of application, whereas triforine provided substantial protection to earlier flower stages up to 6.5 days pre-anthesis. In a separate experiment to quantify post-infection activity ( n = 13,068 flowers), fenbuconazole and triforine significantly suppressed fruit mummification when applied within 2 and 5 days after anthesis, respectively (with inoculation and pollination 1 day after anthesis). Thus, the total window of activity of fenbuconazole in blueberry flowers was 4.5 days, whereas that of triforine was at least 11.5 days. Prevention of ovary colonization by eradicant activity appeared to be the predominant mode for superior activity of triforine against M. vaccinii-corymbosi in flowers. To better manage flower infection by this pathogen, active ingredients such as triforine with superior activity in floral tissues need to be identified and characterized.

Seedlessness is an excellent economical trait, and self-incompatibility (SI) is one of important factors resulting in seedless fruit in Citrus. However, SI molecular mechanism in Citrus is still unclear. In this study, RNA-Seq technology was used to identify differentially expressed genes related to SI reaction of 'Wuzishatangju' (Citrus reticulata Blanco). A total of 35.67GB raw RNA-Seq data was generated and was de novo assembled into 50,364 unigenes with an average length of 897bp and N50 value of 1549. Twenty-three candidate unigenes related to SI were analyzed using qPCR at different tissues and stages after self- and cross-pollination. Seven pollen S genes (Unigene0050323, Unigene0001060, Unigene0004230, Unigene0004222, Unigene0012037, Unigene0048889 and Unigene0004272), three pistil S genes (Unigene0019191, Unigene0040115, Unigene0036542) and three genes (Unigene0038751, Unigene0031435 and Unigene0029897) associated with the pathway of ubiquitin-mediated proteolysis were identified. Unigene0031435, Unigene0038751 and Unigene0029897 are probably involved in SI reaction of 'Wuzishatangju' based on expression analyses. The present study provides a new insight into the molecular mechanism of SI in Citrus at the transcriptional level.

Despite great interest from both the basic science community and from economic stakeholders, research on sex differentiation in persimmons (Diospyros kaki Thunb.) remains limited. Our previous study found that the developmental processes of both male and female floral buds were divided morphologically into 11 stages, of which stage 2 (on June 17) and stage 8 (on April 17 of the following year) were the two crucial morphological stages for sex differentiation. In this study, we used high-performance liquid chromatography-electrospray ionisation tandem mass spectrometry to measure the amounts of indole-3-acetic acid (IAA), gibberellin 3 (GA3), zeatin (ZT), abscisic acid (ABA), and jasmonic acid (JA) in both male and female floral buds at stages 1, 1.5, 2, 6, 7, 8, 10, and 11 to uncover the regulatory effects of endogenous phytohormones on sex differentiation. The results showed that low levels of IAA, ABA, as well as the ratio of ABA to IAA, and high levels of GA3 in male floral buds in the middle of June were related to the formation of three-flower cymes. Moreover, high levels of GA3 in male floral buds at stage 8 may accelerate the arrest of pistil primordia and the development of stamen primordia in the middle of the following April. In addition, high levels of the ratio of ABA to ZT from stages 6–11 might promote the differentiation of male floral buds. However, high levels of IAA from stages 7–10 as well as ZT and ABA from stages 6–10 in female floral buds may stimulate the abortion of stamen primordia and promote the development of pistil primordia, leading to female unisexual flowers. These results are relevant for future research on the regulation of controlled sex differentiation and pollination with exogenous phytohormones.

Morphological and molecular analyses of the Berberidaceae have recognized the Nandinoideae clade of four genera: Caulophyllum, Gymnospermium, Leontice, and Nandina. However, generic relationships of the Nandinoideae remain to be explicitly defined with morphological characteristics. In this study we examined the floral ontogeny of Gymnospermium to gain new insights into the evolution of floral structures in the family and generic relationships of the Nandinoideae. The inflorescence of Gymnospermium is racemose with bracts and floral primordia initiated acropetally. Floral parts form in the order of sepal, stamen, staminode, and carpel. Both sepals and stamens are initiated in three series and each series has two sepals/stamens. Stamen and staminode share a common primordium with the former initiated earlier than the latter. In the Berberidaceae the floral trimery is an ancestral trait, while dimery and its variant (such as non-whorled dimery in Gymnospermium) are a derived feature. The non-whorled pattern of the initiation of sepals and stamens and their dimery provide synapomorphies for the close relationship of Gymnspermium and Leontice in the Nandinoideae.

The majority of gall-inducing nematodes lives in the soil, and induces galls on roots. Nevertheless, some nematodes are able to climb up the stems and induce galls on aerial plant organs. This is the case of Ditylenchus gallaeformans (Oliveira et al., 2013), which induces galls on the inflorescences of Miconia albicans (Sw.) Steud. (1841) and Miconia ibaguensis (Bonpl.) Triana (1871) (Melastomataceae). Under the influence of D. gallaeformans, the flowers of M. albicans and M. ibaguensis do not differentiate in situ. Instead of flowers, the axes of the galled inflorescences are surrounded by emergences with nutritive tissues lining the larval chambers. The nutritive tissues are meristem-like, but distinct from other galls, they have a promeristematic capability. In other words, the nutritive tissues of these galls have totipotent cells, originating new covering emergences with dermal, ground and vascular tissues. Therefore, these galls have an indeterminate growth, which is a novelty for galls in general. Additionally, D. gallaeformans induces a long-distance impact on fruits, which have increased number of carpels. Such long-distance effects indicate that D. gallaeformans is a peculiar colonial parasite, which may compensate the damages of gall inducing mechanisms by favoring, at least partially, its host plant fitness. The number of carpels is a conservative character in most plant species, and the promeristems are maintained only in apical and lateral buds of normal plants. However, D. gallaeformans is capable of manipulating these conservative features in its host plants, and the signaling factors involved in these interactions deserves special attention.

Frugivory and antiherbvore defense are two games played by animals and plants in their arm racing, and they play important roles in the evolution and well-being of the current ecosystem. However, little is known about the history, especially in their early stage, due to lack of related fossil evidence, despite the history of angiosperms has been dated back to the Early Jurassic. Here we report a fossil fruit, Jingwangfructus gen. nov., from the Middle-Late Jurassic (>164 Ma) of Daohugou Village, Inner Mongolia, China, in which the currently earliest evidence of frugivory and antiherbvore defense are identified. The fossil is more or less three dimensionally preserved coalified drupe that has been superficially damaged by different animals in two different ways. The seed coat and pericarp surrounding parenchyma seed content suggest its angiospermous affinity. The seed with a distal micropyle is attached on the base of the former ovary, suggestive of a basal placentation with an orthotropous ovule in the former gynoecium. The occurrence of sclerenchyma in the fleshy pericarp and the damaged pericarp of Jingwangfructus suggests that interaction between the plant and animals has been established by the Late Jurassic. Apparently, the ecological relationship between angiosperms and animals has a history, the length and complexity of which are beyond former assumptions.

The transcriptional activation of genes that encode the ethylene biosynthesis enzyme 1-aminocyclopropane-1-carboxylate oxidase (PhACO3 and PhACO4) during petunia flower senescence has been reported. However, no studies have elaborately investigated their specific roles in ethylene production and flower longevity using genetic manipulation. Hence, we used the CRISPR/Cas9 system to edit the genes (PhACO3 and/or PhACO4) involved in ethylene production and flower longevity in petunia cv. Mirage Rose. The use of the CRISPR/Cas9 system with a sgRNA, which was designed from exon 2 of PhACO3, allows for the specific editing of the genes PhACO3 and/or PhACO4 with high mutation frequency, consequently producing different types of zygotes. The PhACO3 and PhACO4-edited lines 8 and 9 showed remarkably reduced ethylene production (approximately 2.8- to 3.0-fold in corollas and 1.5-fold in pistils) during flowering and extended flower longevity (approximately 9.5 d), while the PhACO3-edited bi-allelic and PhACO4-edited homozygous T0 mutant lines (14 and 23) showed enhanced flower longevity (approximately 8.0 d) compared with 6.0 d for the WT line. This was associated with reduction of PhACO4 protein levels in PhACO4-edited lines, which was confirmed using Western blot analysis and Image J software. Moreover, there was no undesirable editing effect on the PhACO1 gene. The transmission of the edited alleles to the T1 generation was also observed, and ethylene production and flower longevity were identical to those of the T0 mutant lines. Taken together, this study demonstrated not only the single and combined role of PhACO3 and PhACO4 in ethylene production in petunia flowers but also reports improvements in flower longevity by editing of the aforementioned genes using the CRISPR/Cas9 system. Therefore, our study can pave the way for the editing of homologous genes in other ornamental plants using the CRISPR/Cas9 system with a common sgRNA, thus allowing for a time- and cost-effective approach to advancing plant biology and the floricultural industry.

Photoperiod is a major determinant of chasmogamous (CH)-cleistogamous (CL) dimorphic flower development in Viola philippica, and only long-day (LD) conditions induce CL flowers. In this study, it was found that the active gibberellin (GA) content in CL floral buds was higher than in CH floral buds formed under short-day (SD) conditions, suggesting that the biosynthesis of active GAs is enhanced by a longer photoperiod and may be associated with dimorphic flower development. Thus, the next step was to molecularly characterize the key V. philippica GA synthesis genes GA 20-oxidase (VpGA20ox) and GA 3-oxidase (VpGA3ox). In terms of the expression of VpGA20ox and VpGA3ox, it was found that the active GAs could be upregulated in developing pistils under both LD and SD conditions to develop functional pistils, and GAs could also accumulate in the stamens under SD conditions. The anthers and the adjacent petals were well developed under SD conditions. In contrast, the above-mentioned floral organs displayed low GA contents under LD conditions and were poorly developed. Although the application of paclobutrazol, an inhibitor of GA synthesis, did not reverse CL development under LD conditions, exogenous GAs could partially trigger the transition from CH to CL flowers under relative SD conditions (≤12 h daylight). This was coupled with the downregulation of B-class MADS-box genes, thereby restraining stamen and petal development. Both VpGA20ox and VpGA3ox exhibited similar expression profiles with B-class MADS-box genes in the development of the stamens and petals. Therefore, in response to photoperiod, GA signaling could affect the expression of B-class homeotic genes and regulate dimorphic flower development in Viola. As a compensation for poorly-developed nectaries, anthers, and petals, filament elongation, style shortness, and inward bending could ensure self-pollination in CL flowers. This work provides new insights into the regulation of CH-CL floral development and the evolutionary significance of the formation of dimorphic flowers.

Valerianaceae provides a model clade for examining diversification in floral shape, especially involving size, bilateral symmetry, asymmetry, and handedness. Fedia species have pink, strongly bilaterally symmetrical corollas while Valerianella species generally have white, near-radially symmetrical corollas. In this study we examine the early floral ontogeny of Valerianella locusta and Fedia graciliflora to compare early growth and developmental traits that may lead to the difference in their mature flowers. Fedia graciliflora and V. locusta inflorescences at varying stages of development were collected and dissected to remove subtending bracts and bracteoles. Images of floral development were taken using a stereomicroscope and a Scanning Electron Microscope. The inflorescence primordium appears to continuously bifurcate as it grows, resulting in an inflorescence with densely packed flowers of varying ages. Flowers of both F. graciliflora and V. locusta initiate petals and stamens simultaneously on a ring-like common primordium. We demonstrate that stamen primordia arise in a spiral pattern, grow faster than other organs, and dominate growth until they are nearly mature. Five petal primordia and two stamens arise in F. graciliflora. In contrast, in V. locusta which has three stamens, four petal primordia initiate, which appear as an open ring-like or U-shaped primordium with a furrow on one side. This likely provides the space for the additional large stamen. Sepal development is not evident and lobes are lacking. The gynoecium does not begin to develop until the flower bud is nearing maturity. These data provide a framework for future developmental genetic work in these species.

Rubisco is the key enzyme of photosynthetic CO2 fixation, whereas a Rubisco small subunit homolog (OsRbcS1) in rice, was exclusively expressed in non-photosynthetic organs. In this study, OsRbcS1-like genes were identified in several plant species including foxtail millet (SiRbcS1), tomato (SlRbcS1), Lotus japonicus (LjRbcS1), grape (VvRbcS1A, VvRbcS1B) and Selaginella moellendorffii (SmRbcS1A, SmRbcS1B). RT-PCR analysis revealed that SiRbcS1 was expressed in seeds of foxtail millet. In tomato, SlRbcS1 was expressed in the stamen, pistil and green fruit. In L. japonicus, LjRbcS1 was expressed in the root, nodule and seed. In grape, both VvRbcS1A and VvRbcS1B were expressed in mature leaves and the green berry. In S. moellendorffii, SmRbcS1A and SmRbcS1B displayed similar expression patterns and were expressed in the rhizome and root. Although these OsRbcS1-like genes were expressed in photosynthetic organs in S. moellendorffii, its expression levels were higher in non-photosynthetic organs than in photosynthetic organs. These results suggest that OsRbcS1-like RbcS functions in metabolic pathways other than photosynthetic CO2 fixation in various organs.

In S-RNase-based self-incompatibility, S-RNase was previously thought to function as a selective RNase that inhibits pollen whose S-haplotype matches that in the pistil. In this study, we showed that S-RNase has a distinct effect on the regulation of Ca2+-permeable channel activity in the apical pollen tube in Pyrus pyrifolia. While non-self S-RNase has no effect, self S-RNase decreases the activity of Ca2+ channels and disrupts the Ca2+ gradient at the tip of the growing pollen tube during the gametophytic self-incompatibility (GSI) response. Extracellular Ca2+ influx was suppressed 5min after self S-RNase treatment, and self-pollen tube growth was reduced at 50min after self S-RNase treatment. In the self-incompatible response, the expression of Ca2+-related genes was inhibited before RNA degradation. Therefore, self S-RNase suppresses Ca2+ influx prior to arresting pollen tube growth via RNA degradation.