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Background: "Bairihua", a variety of the Catalpa bungei, has a large amount of flowers and a long flowering period which make it an excellent material for flowering researches in trees. SPL is one of the hub genes that regulate both flowering transition and development., Results: SPL homologues CbuSPL9 was cloned using degenerate primers with RACE. Expression studies during flowering transition in "Bairihua" and ectopic expression in Arabidopsis showed that CbuSPL9 was functional similarly with its Arabidopsis homologues. In the next step, we used Y2H to identify the proteins that could interact with CbuSPL9. HMGA, an architectural transcriptional factor, was identified and cloned for further research. BiFC and BLI showed that CbuSPL9 could form a heterodimer with CbuHMGA in the nucleus. The expression analysis showed that CbuHMGA had a similar expression trend to that of CbuSPL9 during flowering in "Bairihua". Intriguingly, ectopic expression of CbuHMGA in Arabidopsis would lead to aberrant flowers, but did not effect flowering time., Conclusions: Our results implied a novel pathway that CbuSPL9 regulated flowering development, but not flowering transition, with the participation of CbuHMGA. Further investments need to be done to verify the details of this pathway.

Background: Long non-coding RNAs (lncRNAs) have crucial roles in various biological regulatory processes. However, the study of lncRNAs is limited in woody plants. Catalpa bungei is a valuable ornamental tree with a long cultivation history in China, and a deeper understanding of the floral transition mechanism in C. bungei would be interesting from both economic and scientific perspectives., Results: In this study, we categorized C. bungei buds from early flowering (EF) and normal flowering (NF) varieties into three consecutive developmental stages. These buds were used to systematically study lncRNAs during floral transition using high-throughput sequencing to identify molecular regulatory networks. Quantitative real-time PCR was performed to study RNA expression changes in different stages. In total, 12,532 lncRNAs and 26,936 messenger RNAs (mRNAs) were detected. Moreover, 680 differentially expressed genes and 817 differentially expressed lncRNAs were detected during the initiation of floral transition. The results highlight the mRNAs and lncRNAs that may be involved in floral transition, as well as the many lncRNAs serving as microRNA precursors. We predicted the functions of lncRNAs by analysing the relationships between lncRNAs and mRNAs. Seven lncRNA-mRNA interaction pairs may participate in floral transition., Conclusions: This study is the first to identify lncRNAs and their potential functions in floral transition, providing a starting point for detailed determination of the functions of lncRNAs in C. bungei.

Background and Aims: Flowering plants display considerable variation in mating system, specifically the relative frequency of cross- and self-fertilization. The majority of estimates of outcrossing rate do not account for temporal variation, particularly during the flowering season. Here, we investigated seasonal variation in mating and fertility in Incarvillea sinensis (Bignoniaceae), an annual with showy, insect-pollinated, 'one-day' flowers capable of delayed selfing. We examined the influence of several biotic and abiotic environmental factors on day-to-day variation in fruit set, seed set and patterns of mating., Methods: We recorded daily flower number and pollinator abundance in nine 3 × 3-m patches in a population at Mu Us Sand land, Inner Mongolia, China. From marked flowers we collected data on daily fruit and seed set and estimated outcrossing rate and biparental inbreeding using six microsatellite loci and 172 open-pollinated families throughout the flowering period., Key Results: Flower density increased significantly over most of the 50-d flowering season, but was associated with a decline in levels of pollinator service by bees, particularly on windy days. Fruit and seed set declined over time, especially during the latter third of the flowering period. Multilocus estimates of outcrossing rate were obtained using two methods (the programs MLTR and BORICE) and both indicated high selfing rates of ∼80 %. There was evidence for a significant increase in levels of selfing as the flowering season progressed and pollinator visitation declined. Biparental inbreeding also declined significantly as the flowering season progressed., Conclusions: Temporal variation in outcrossing rates may be a common feature of the mating biology of annual, insect-pollinated plants of harsh environments but our study is the first to examine seasonal mating-system dynamics in this context. Despite having large flowers and showy floral displays, I. sinensis attracted relatively few pollinators. Delayed selfing by corolla dragging largely explains the occurrence of mixed mating in I. sinensis, and this mode of self-fertilization probably functions to promote reproductive assurance when pollinator service is limited by windy environmental conditions and competition from co-occurring flowering plants., (© The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

PISTILLATA (PI) plays crucial roles in Arabidopsis flower development by specifying petal and stamen identities. To investigate the molecular mechanisms underlying organ development of woody angiosperm in Catalpa, we isolated and identified a PI homologue, referred to as CabuPI (C. bungei PISTILLATA), from two genetically cognate C. bungei (Bignoniaceae) bearing single and double flowers. Sequence and phylogenetic analyses revealed that the gene is closest related to the eudicot PI homologues. Moreover, a highly conserved PI-motif is found in the C-terminal regions of CabuPI. Semi-quantitative and quantitative real time PCR analyses showed that the expression of CabuPI was restricted to petals and stamens. However, CabuPI expression in the petals and stamens persisted throughout all floral development stages, but the expression levels were different. In 35S::CabuPI transgenic homozygous pi-1 mutant Arabidopsis, the second and the third whorl floral organs produced normal petals and a different number of stamens, respectively. Furthermore, ectopic expression of the CabuPI in transgenic wild-type or heterozygote pi-1 mutant Arabidopsis caused the first whorl sepal partially converted into a petal-like structure. These results clearly reveal the functional conservation of PI homologues between C. bungei and Arabidopsis., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

The presence and function of several proteins secreted into floral nectars has been described in recent years. Here we report the presence of at least eight distinct proteins secreted into the floral nectar of the tropical tree Jacaranda mimosifolia (Bignoniaceae). Steps were initiated to identify and characterize these proteins in order to determine potential functions. The N-terminal sequence of the major Jacaranda nectar protein, JNP1, at 43 kDa contained similarity with members of the plant GDSL lipase/esterase gene family. Based upon this sequence, a full-length cDNA was isolated and predicted to encode a mature protein of 339 amino acids with a molecular mass of 37 kDa. Both raw nectar and heterologously expressed JNP1 displayed lipase/esterase activities. Interestingly, J. mimosifolia flowers produce an opaque, white colored nectar containing spherical, lipophilic particles approximately 5 microm in diameter and smaller. GS-MS analysis also identified the accumulation of free fatty acids within the nectar. It is proposed that JNP1 hydrolyzes Jacaranda nectar lipids with the concomitant release of free fatty acids. Potential functions of JNP1 in relation to pollinator attraction and prevention of microbial growth within nectar are briefly discussed.