Zumajo-Cardona Cecilia, Ambrose Barbara A, Madrigal Yesenia, Pabón-Mora Natalia
Botanical Garden, University of Padova, Padova, Italy.
Department of Biology, University of Padova, Italy.
Ann Bot. 2025 May 4. doi: 10.1093/aob/mcaf079.
Dry dehiscent fruits have independently evolved multiple times during angiosperm diversification. A striking example is the convergent evolution of Brassicaceae siliques and Papaveraceae pods, both formed by two fused carpels forming valves, that meet at a replum or replum-like structure. In both cases, valve separation occurs through a dehiscence zone at the valve margins in contact with the replum. In Arabidopsis, fruit development is regulated by transcription factors: FRUITFULL (FUL) ensures proper valve cell division, REPLUMLESS (RPL) specifies replum identity, and SHATTERPROOF (SHP1/2) genes pattern the dehiscence zone. SHP1/2 also regulate INDEHISCENT (IND) for lignified layer formation and ALCATRAZ (ALC) and SPATULA (SPT) for the non-lignified layer, with the network antagonized by APETALA2 (AP2), which influences replum formation and valve margin growth.
Using previously published and new In situ RNA hybridization expression data, we evaluated how this network applies to basal eudicots.
In Bocconia frutescens, homolog expression suggests conserved roles for FUL and AP2 in fruit wall proliferation, acting antagonistically to ALC and RPL homologs localized to the dehiscence zone. A role for STK homologs in dehiscence zone formation cannot be excluded, while the role of AG-like genes, the closest homologs of SHP during fruit development is unlikely.
Our findings indicate significant rewiring of the fruit developmental network between basal and core eudicots, underscoring the need for functional studies in non-eudicot species to validate this framework.
在被子植物多样化过程中，干燥开裂果实已多次独立进化。一个显著的例子是十字花科角果和罂粟科蒴果的趋同进化，二者均由两个融合的心皮形成瓣膜，并在假隔膜或类似假隔膜的结构处相接。在这两种情况下，瓣膜分离通过瓣膜边缘与假隔膜接触处的开裂区发生。在拟南芥中，果实发育受转录因子调控：FUL（FRUITFULL）确保瓣膜细胞正常分裂，RPL（REPLUMLESS）决定假隔膜特征，SHP1/2（SHATTERPROOF）基因决定开裂区模式。SHP1/2还调控IND（INDEHISCENT）以形成木质化层，以及ALC（ALCATRAZ）和SPT（SPATULA）以形成非木质化层，该网络受AP2（APETALA2）拮抗，AP2影响假隔膜形成和瓣膜边缘生长。
利用先前发表的和新的原位RNA杂交表达数据，我们评估了该网络如何应用于基部真双子叶植物。
在博落回中，同源基因表达表明FUL和AP2在果实壁增殖中具有保守作用，与定位在开裂区的ALC和RPL同源基因起拮抗作用。不能排除STK同源基因在开裂区形成中的作用，而AG类基因在果实发育过程中作为SHP最接近的同源基因，其作用不太可能。
我们的研究结果表明基部和核心真双子叶植物之间果实发育网络发生了显著重组，强调了在非真双子叶植物物种中进行功能研究以验证该框架的必要性。
