Dirks-Mulder Anita, Ahmed Israa, Uit Het Broek Mark, Krol Louie, Menger Nino, Snier Jasmijn, van Winzum Anne, de Wolf Anneke, Van't Wout Martijn, Zeegers Jamie J, Butôt Roland, Heijungs Reinout, van Heuven Bertie Joan, Kruizinga Jaco, Langelaan Rob, Smets Erik F, Star Wim, Bemer Marian, Gravendeel Barbara
Endless Forms Group, Naturalis Biodiversity Center, Leiden, Netherlands.
Faculty of Science and Technology, University of Applied Sciences Leiden, Leiden, Netherlands.
Front Plant Sci. 2019 Feb 19;10:137. doi: 10.3389/fpls.2019.00137. eCollection 2019.
Efficient seed dispersal in flowering plants is enabled by the development of fruits, which can be either dehiscent or indehiscent. Dehiscent fruits open at maturity to shatter the seeds, while indehiscent fruits do not open and the seeds are dispersed in various ways. The diversity in fruit morphology and seed shattering mechanisms is enormous within the flowering plants. How these different fruit types develop and which molecular networks are driving fruit diversification is still largely unknown, despite progress in eudicot model species. The orchid family, known for its astonishing floral diversity, displays a huge variation in fruit dehiscence types, which have been poorly investigated. We undertook a combined approach to understand fruit morphology and dehiscence in different orchid species to get more insight into the molecular network that underlies orchid fruit development. We describe fruit development in detail for the epiphytic orchid species and compare it to two terrestrial orchid species: and . Our anatomical analysis provides further evidence for the split carpel model, which explains the presence of three fertile and three sterile valves in most orchid species. Interesting differences were observed in the lignification patterns of the dehiscence zones. While and develop a lignified layer at the valve boundaries, fruits did not lignify at these boundaries, but formed a cuticle-like layer instead. We characterized orthologs of fruit-associated MADS-domain transcription factors and of the Arabidopsis dehiscence-related genes and in , and found that the key players of the eudicot fruit regulatory network appear well-conserved in monocots. Protein-protein interaction studies revealed that MADS-domain complexes comprised of FRUITFULL (FUL), SEPALLATA (SEP) and AGAMOUS (AG) /SHATTERPROOF (SHP) orthologs can also be formed in , and that the expression of , and can be associated with dehiscence zone development similar to Arabidopsis. Our expression analysis also indicates differences, however, which may underlie fruit divergence.
开花植物中果实的发育使得种子能够有效传播，果实可分为裂果和闭果。裂果在成熟时会裂开以散播种子，而闭果不会裂开，种子通过各种方式传播。开花植物中果实形态和种子开裂机制的多样性极为丰富。尽管在双子叶植物模式物种方面取得了进展，但这些不同果实类型如何发育以及哪些分子网络驱动果实多样化在很大程度上仍不清楚。兰科以其惊人的花多样性而闻名，其果实开裂类型差异巨大，但相关研究较少。我们采用综合方法来了解不同兰花物种的果实形态和开裂情况，以便更深入地了解兰花果实发育的分子网络。我们详细描述了附生兰花物种的果实发育过程，并将其与两种地生兰花物种： 和 进行比较。我们的解剖分析为心皮分裂模型提供了进一步证据，该模型解释了大多数兰花物种中三个可育瓣和三个不育瓣的存在。在开裂区的木质化模式上观察到了有趣的差异。 和 在瓣边界处形成了木质化层，而 果实的这些边界处没有木质化，而是形成了类似角质层的层。我们在 中鉴定了与果实相关的MADS结构域转录因子以及拟南芥开裂相关基因 和 的直系同源物，发现双子叶植物果实调控网络的关键参与者在单子叶植物中似乎也高度保守。蛋白质 - 蛋白质相互作用研究表明，由FRUITFULL（FUL）、SEPALLATA（SEP）和AGAMOUS（AG）/SHATTERPROOF（SHP）直系同源物组成的MADS结构域复合物也可以在 中形成，并且 、 和 的表达与拟南芥类似，可与开裂区发育相关。然而，我们的表达分析也表明存在差异，这可能是果实分化的基础。
