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Premise: Leaf subepidermal secretory cavities are a notable trait in Myrtaceae, but their formation is still controversial because of the lack of consensus on their ontogeny among authors. Knowledge about the compounds present in these cavities has grown over the last few years, demonstrating that terpenoid‐rich oils are not their unique content. These two points are the focus of this study on the ontogeny, structure, and contents of secretory cavities in neotropical Myrtaceae. Methods: We used histochemical tests and Raman analysis to verify the basic chemical composition of the cavity contents of nine species. We studied the ontogeny of glands in one species, comparing aldehyde‐fixed tissues and fresh sections mounted in an inert medium. Results: We observed schizogenous development and appearance of the secretory cavities and found that sample processing may induce cell breakdown, which can be misinterpreted as lysigeny. The content of these cavities contains putative terpenes, resins, carbonyl groups, and flavonoids. Conclusions: Our findings support the hypothesis that the lysigenous appearance of the oil glands is a technical artifact. These tissue distortions must be considered when interpreting the development of this type of secretory structure. Moreover, the basic analyses of chemical constituents show for the first time that the glands of neotropical Myrtaceae are potential reservoirs of some compounds such as flavonoids previously reported as novelties for a few other myrtaceous species. Because some of them are non‐lipid compounds, the idea that the glands are just oil repositories is no longer applicable. [ABSTRACT FROM AUTHOR]

Seed morphology could provide significant characters for understanding the diversification of some clades in Bromeliaceae subfamily Bromelioideae, but little is known about the anatomical diversity and ontogeny of the seed coat in this diverse subfamily. We analysed the morphoanatomy of the seed coat for 48 species from 25 genera of the major lineages of Bromelioideae, from which we selected four species for ontogenetic analysis. Standard techniques for light microscopy were adapted for the anatomical study of seeds. Thirty-three variable characters were described and compared. Flattened or angular usually exappendiculate, tegmic-endotestal seeds, with secondarily thickened endotesta and undulate or costate tegmen, are common characteristics of the tankless lineages. Long oblongoid–obovoid, appendaged or exappendiculate, exclusively tegmic and mucilaginous seeds are common to core Bromelioideae. Anatomical features of the exotegmen and testa and the number of parenchyma layers in the raphe were more variable and especially useful in delimiting genera and some species. The ontogenetic analysis was essential to propose the primary morphological homology hypotheses for the seed coat characters. Seed coat morphoanatomical features offer a promising source of phylogenetically informative characters for integrative and character evolution approaches for Bromelioideae and possibly other subfamilies of Bromeliaceae. [ABSTRACT FROM AUTHOR]

Tapetal cells comprise an anther tissue fundamental to pollen grain development. They are associated with endoreduplication events, which culminate in polyploid and multinucleated cells, high metabolic activity, and different organelle arrangements to support all the development of the pollen grains. Passiflora species present a secretory tapetum, with diversity in the number and size of nuclei. Tapetal cells undergo numerous changes in a short period of development when compared to the plant's life span. To improve our knowledge of tapetum development, tests assessing ploidy levels, anatomy, cytochemistry, transmission electron microscopy, flow cytometry, as well as conventional and molecular cytogenetics were used in Passiflora actinia and P. elegans. The current data show striking differences in nuclear organisation during tapetal cell development, including mono to quadrinucleate cells, and ploidy levels from 2n to 32n. One of the most peculiar features was the atypical behaviour of the endoplasmic reticulum (ER), which accumulated in the cell border, similar to a 'cER', as well as large dictyosomes. This endomembrane configuration may be related to the tapetum nutritional network and secretion of compounds at the end of meiosis. Another atypical feature of the ER was the formation of an invagination to establish 'binucleated' polyploid cells. This membrane projection appears when the nuclei form two lobes, as well as when it organises a nucleoplasmic reticulum. These data demonstrate that there are important ultrastructural changes in tapetal cells, including organelle arrangements, ploidy levels, and nuclear activity, common to P. actinia and P. elegans, but different from the plant model A. thaliana. [ABSTRACT FROM AUTHOR]

Cyperaceae representatives present peculiar microsporogenesis and microgametogenesis, which raises the question of how regular the sedge pollen is. In order to answer this question, preanthesis pollen grains of Cyperaceae individuals were analyzed under different tools such as light and transmission electron microscopy, which included cytochemistry and immunogold procedures. The results showed that maturing pollen in Cyperaceae presents some unusual endomembrane behaviors. Endoplasmic reticulum and dictyosomes are concerned in classic secretion pathways in vegetative cells, and possibly the late breakdown of degenerative microspores. However, cortical and concentric endoplasmic reticulum are also present and are possibly related to other functions aside the biosynthetic pathway. Unconventional secretion of large membrane‐bound bodies containing cell wall precursors was also observed and confirmed by immunogold. However, since these bodies most likely receive material from dictyosomes, as observed in silver nitrate reaction, the "unconventional" status of this secretion is debatable. Reports of the literature show that these unusual endomembrane formations are not exclusive of the sedge pollen, but little attention have been given to them so far. This could represent an opportunity to re‐examine our understanding on the endomembrane system in pollen cells in general. [ABSTRACT FROM AUTHOR]

During microsporogenesis in Cyperaceae, an asymmetric tetrad of microspores is formed, establishing a pseudomonad. Three microspores undergo programmed cell death, whereas the functional microspore goes though microgametogenesis. A full understanding of this process remains elusive, but knowledge of its stages, cell death meaning and coexistence of multiple cell lineages occurring in such restricted spaces is of great cytological interest. Therefore, a comparative study was made in Cyperaceae and Juncaceae to characterize pollen features and development using light and electron microscopy and cytochemical tests. Evidence from sporopollenin suggests that pseudomonads are derived from pollen tetrads like those in Juncaceae, and data collected allowed the establishment of five pseudomonad development stages. In summary, the late meiosis cytokinesis and precocious pollen mitosis I seem to be associated with pseudomonad formation. Vacuolation occurs later, with continuous autophagy of degenerative microspores, suggesting cell death to the benefit of pollen fitness. Reserves are accumulated as starch, depending on environmental conditions. During microgametogenesis, different cellular lineages appear to be isolated by callose, giving each cell metabolic autonomy. This process of pseudomonad establishment allows the formation of a longevous, rapidly germinating, tricellular pollen, which could be key to the great adaptative success of Cyperaceae. [ABSTRACT FROM AUTHOR]

In Nidularium, inflorescence branches are subtended by large floral bracts, in which water accumulates. The branching pattern is obscured because their internodes remain short, hampering their interpretation. This study focuses on the development of the inflorescence in N. innocentii, combining different approaches in order to understand its architecture and summarize it in a three-dimensional (3D) model. We also present the interpretation of tankinflorescence development, recognizing the processes that have taken place in the evolution of this structure in this group. The inflorescence was typified based on Troll's and Weberling's systems. Development was studied using light microscopy and X-ray microcomputed tomography. The system is polytelic; the main axis ends in the main florescence and bears lateral paraclades with coflorescences. Each lateral branch develops in the axil of a bract, which is large and displays alternate arrangement. No prophylls were observed in the system. In the 3D reconstruction, the volume of the model was calculated. The volume of the empty region is c. 2.4 times higher than the plant material. Tank-inflorescence development seems to have occurred by the combination of three processes: bract disposition and its overgrowth; failure in internode elongation; and paraclade flattening. The tank-inflorescence evolved in a few groups of core bromelioids, and may be associated with floral protection. [ABSTRACT FROM AUTHOR]

Despite the wide appreciation of seedless grapes, little is known about the molecular mechanisms that drive the stenospermocarpic seedless-type phenotype in grapevine. In order to address the molecular mechanisms that control seedlessness in grapevine, our study aimed to characterize VviAGL11, a class D MADS-box transcription factor gene that has been proposed as the major candidate gene involved in Vitis vinifera seed morphogenesis. VviAGL11 allelic variations in seeded and seedless grapevine cultivars were determined, and its correlations with allele-specific steady-state mRNA levels were investigated. VviAGL11 relative expression was significantly higher in seeds at 2, 4, and 6 weeks after fruit set, whereas in the seedless grape its transcript levels were extremely low in all stages analyzed. In situ hybridization revealed transcript accumulation specifically in the dual endotesta layer of the seeds, which is responsible for elongation and an increase of cell number, a necessary step to determine the lignification and the final seed size. No hybridization signals were visible in the seedless grapevine tissues, and a morphoanatomical analysis showed an apparent loss of identity of the endotesta layer of the seed traces. Ectopic expression of VviAGL11 in the Arabidopsis SEEDSTICK mutant background restored the wild-type phenotype and confirmed the direct role of VviAGL11 in seed morphogenesis, suggesting that depletion of its expression is responsible for the erroneous development of a highly essential seed layer, therefore culminating in the typical apirenic phenotype. [ABSTRACT FROM AUTHOR]

Tillandsioideae are composed of nine genera, most of these with unclear delimitation. The morphoanatomy of ovules and ovaries of 83 species from seven different genera was studied under light or scanning electron microscopy to contribute to the understanding of the relationships in the group. The nucellar epidermis and the parietal tissue showed a regular pattern for all Tillandsioideae. The presence of chalazal appendages, however, and their shape and size varied between the genera analysed. Most species had a single acuminate chalazal appendage. Catopsis was the only genus with multiple appendages. Guzmania and Racinaea lacked this structure. The integuments also presented a variable length and thickness among the different genera. The four to six layers of the outer integument were unique in Catopsis and the three cell layers condition in the inner integument of Tillandsia should be a retained feature as it was also observed in Catopsis. Many characteristics in ovule morphology presented here have great systematic value for distinguishing genera of the Tillandsioideae. In addition, these features can also help in the understanding of ovule evolution in Bromeliaceae as a whole. [ABSTRACT FROM AUTHOR]

In Bromelioideae, the so-called nidularioid complex contains closely related genera, the circumscription of which has been problematic. The goal of this study was to describe the ovary and ovule anatomy of six species of the nidularioid complex belonging to Canistropsis, Canistrum, Edmundoa, Neoregelia, Nidularium and Wittrockia and to use these characters in a parsimony analysis of relationships. In all analysed species, schizogenous-type aerenchyma is present in the ovarian mesophyll. Edmundoa lindenii has trichomes on the ovary surface, and this character appears to be an autapomorphy for the species. Canistrum aurantiacum exhibited some autapomorphies, such as four cell layers in the outer integument, non-elongated cells in the nucellar epidermis and three or four layers of cells in the parietal tissue. In the remaining species of the complex, the presence of transversally orientated ovules and anticlinally elongated cells in the outer integument in the micropylar region appear to be synapomorphies. Canistrum aurantiacum shares few characters with the other species; these results and the latest phylogenetic analysis show that Canistrum spp. do not belong to the current nidularioid clade. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177, 66-77. [ABSTRACT FROM AUTHOR]

Background and Aims: Recent studies have documented numerous morphoanatomical variations for the seed coat in Bromeliaceae. However, the structural diversity and character evolution of the embryo within this family remain largely unexplored. Given the embryo's significance in plant diversification, this research aims to investigate the morphology and key anatomical features of Bromeliaceae embryos, providing insights into character evolution, taxonomic applications, and reproductive biology., Methods: We analysed samples of 88 species from 50 genera representing the major lineages of Bromeliaceae, using standard plant microtechniques adapted for seeds. To determine ancestral traits, parsimony and maximum likelihood analyses were performed in a consensus supertree combining previous phylogenies., Key Results: This study identified 14 informative characters, highlighting significant differences among groups, particularly in embryo morphology, differentiation, and anatomical traits. Our analysis revealed that undifferentiated embryos with a vestigial cotyledonary hyperphyll are plesiomorphic in Bromeliaceae. They have evolved multiple times into rudimentary or well-differentiated embryos, the latter exhibiting intermediate or large sizes and diverse cotyledonary hyperphyll morphologies. The cotyledonary hypophyll varies in sheath lobes and slit morphologies, and is curved or expanded exclusively in Bromelioideae representatives. Similarly, several patterns of hypocotyl/radicle constriction are unique to Tillandsioideae and plesiomorphic for this clade. Although rudimentary embryos exhibit simpler and more uniform anatomy, they are distinct from undifferentiated embryos, which lack defined organs and internal tissues. In contrast, well-differentiated embryos possess more complex anatomical structures, including a multi-layered shoot apical meristem and root cap, a broad cotyledonary sheath, and often leaf primordia, the latter evolving independently several times only in large embryos., Conclusions: Our findings reveal a previously unknown morphological diversity for embryos in Bromeliaceae, enhancing our understanding of the morphological evolution of its major lineages. In addition, it introduces new informative characters for the family's systematics and broadens our understanding of the reproductive biology of Bromeliaceae., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Anther development is a complex process regulated by a myriad of transcription factors belonging to distinct protein families. In this study, we focus on the functional characterization of OsbHLH35, a basic Helix-Loop-Helix (bHLH) TF that regulates anther development in rice. Plants overexpressing OsbHLH35 presented small and curved anthers, leading to a reduction of 72 % on seed production. Rice transgenic plants expressing GUS reporter gene under the control of OsbHLH35 promoter (pOsbHLH35::GUS) showed that this TF specifically accumulates in anthers at the meiosis stage and in other spikelet tissues. Yeast one-hybrid screening identified three members of the Growth-Regulating Factor (GRF) family, OsGRF3, OsGRF4, and OsGRF11, as transcriptional regulators of OsbHLH35. Transactivation assay showed that OsGRF11 negatively regulates OsbHLH35 expression in Arabidopsis protoplasts. This regulation was also observed in planta through the analysis of transgenic plants overexpressing OsGRF11 (OsGRF11OE), confirming that OsGRF11 is a negative regulator of OsbHLH35 in rice. Our data suggest that OsbHLH35 plays an essential role in anther development in rice and the fine control of its expression is crucial to ensure proper seed production., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In Bromeliaceae, various traits have evolved for the uptake and storage of water; however, their roles in bromeliad inflorescences remain unresolved. This study investigates the role of water in the flowers and inflorescences of Nidularium innocentii, and describes water as a protection mechanism. Individuals were divided into groups with and without water provision in inflorescences. Both groups were maintained with water in soil and leaves under the same environmental conditions. During anthesis, individuals were collected, and inflorescences were measured. Another specimen was prepared and scanned using X-ray microtomography (μCT), generating a high-resolution 3D model that was converted into a discretized geometry. Heat transfer finite element analysis (FEA) of the μCT-based geometry was then performed to simulate external temperature dissipation with the presence and absence of water in 3D. Flower size in the control group was significantly larger, and many injuries were observed in the drought group. FEA data indicated that the water environment led to lower temperature variation when compared to the air environment by significantly alleviating thermal amplitude. Water acted as a temperature stabilizer for the inflorescence, while its absence initiated physiological stress responses., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Seedlessness in grapes is a desirable trait, especially for in natura consumption. Previously, we showed that VviAGL11 is the main responsible gene for seed morphogenesis in grapevine. Here we tested the function of this gene in grapevine with the use of plant plasmids. VviAGL11 was cloned into silencing and overexpression versions of p28iIR plasmid. Reproductive grapevine bunches from different seeded and seedless cultivars were separately treated with VviAGL11-harboring plasmids, along with controls. Plasmids were detected in leaves after a month of treatment, and berries, leaves, stems and seeds were analyzed for ectopic gene expression by RT-qPCR after 90 days of plasmid injection. Fruits from the seedless 'Linda' treated with the VviAGL11-overexpression plasmid showed high expression levels of VviAGL11 and exhibited small seeds that were not found in the untreated control samples. Mature grapes from seeded 'Italia' and 'Ruby' bunches treated with the VviAGL11-silencing plasmid showed decreased VviAGL11 expression, reduced number of seeds and increased number of seed traces. The present study confirms that VviAGL11 is a key master regulator of seed morphogenesis in grapevine and corroborates with the applicability of plant plasmids as promising biotechnological tools to functionally test genes in perennial plants in a rapid and confident way., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Investigation into the initial developmental stages of a given structure is fundamental for precise characterization as well as for comparative analysis in relation to other taxa when homologies are established. For the Anacardiaceae family, investigations of the initial development of the pericarp or its basic histological sites, the epicarp, mesocarp and endocarp, are relevant since these regions are of taxonomic and phylogenetic importance. The initial stages of endocarp development in Lithraea brasiliensis were studied using light microscopy. In L. brasiliensis, the fruits are of the drupe type. The endocarp originates exclusively in the epidermis of the locular cavity and is composed of only three strata. The crystalliferous layer, typical in fruits of the Anacardiaceae family, originates in the carpelar mesophyll and runs adjacent to the outermost layer of the endocarp. The endocarp in Lithraea brasiliensis is of the Anacardium type. The results of the present study are important for the identification of the Lithraea species that occur in the state of Rio Grande do Sul. In L. molleoides, the crystalliferous layer was shown to originate from the locular epidermis and this developmental aspect enables it to be differentiated from L. brasiliensis and demonstrates that there is variability of endocarp development in Lithraea.

Rice productivity is largely affected by low temperature, which can be harmful throughout plant development, from germination to grain filling. Germination of indica rice cultivars under cold is slow and not uniform, resulting in irregular emergence and small plant population. To identify and characterize novel genes involved in cold tolerance during the germination stage, two indica rice genotypes (sister lines previously identified as cold-tolerant and cold-sensitive) were used in parallel transcriptomic analysis (RNAseq) under cold treatment (seeds germinating at 13 °C for 7 days). We detected 1,361 differentially expressed transcripts. Differences in gene expression found by RNAseq were confirmed for 11 selected genes using RT-qPCR. Biological processes enhanced in the cold-tolerant seedlings include: cell division and expansion (confirmed by anatomical sections of germinating seeds), cell wall integrity and extensibility, water uptake and membrane transport capacity, sucrose synthesis, generation of simple sugars, unsaturation of membrane fatty acids, wax biosynthesis, antioxidant capacity (confirmed by histochemical staining of H2O2), and hormone and Ca(2+)-signaling. The cold-sensitive seedlings respond to low temperature stress increasing synthesis of HSPs and dehydrins, along with enhanced ubiquitin/proteasome protein degradation pathway and polyamine biosynthesis. Our findings can be useful in future biotechnological approaches aiming to cold tolerance in indica rice., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)