Department of Biological Sciences and Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, 382355, India.
20/20 Seed Labs Inc., Nisku, AB, T9E 7N5, Canada.
Plant Reprod. 2024 Nov 27;38(1):2. doi: 10.1007/s00497-024-00511-z.
Hybridization barriers in Brassicaceae play a pivotal role in governing reproductive success and maintaining speciation. In this perspective, we highlight recent advances revealing the intricate molecular mechanisms and the interplay among key players governing these barriers. Recent studies have shed light on the molecular mechanisms that govern hybridization barriers in Brassicaceae. The interplay between pollen coat proteins, stigmatic receptors, and signaling peptides plays a crucial role in determining the success of pollination. At the core of this system, autocrine stigmatic RALF peptides (sRALF) maintain the stigmatic barrier by activating the FERONIA (FER) and ANJEA (ANJ) receptor complex, triggering the RAC/ROP-RBOHD pathway and subsequent reactive oxygen species (ROS) production. It is now established that incompatible pollen rejection is mediated by two parallel pathways: the FER-RAC/ROP-RBOHD pathway, which generates ROS, and the ARC1-mediated pathway, which degrades compatible factors required for pollen growth. Conversely, compatible pollen overcomes the stigmatic barrier through the action of pollen coat proteins (PCP-B) and paracrine pollen-derived RALF peptides (pRALF), which compete with autocrine sRALF for receptor binding, enabling successful pollen hydration and tube penetration. The "lock-and-key" mechanism involving sRALF and pRALF provides species-specific recognition of compatible pollen. These findings offer valuable insights into the molecular basis of hybridization barriers and open new possibilities for overcoming these barriers in interspecific and intergeneric crosses within Brassicaceae, with potential applications in plant breeding and crop improvement. Future research should focus on elucidating the evolutionary dynamics of these signaling pathways and exploring their manipulation for crop breeding purposes.
芸薹科植物的杂交障碍在生殖成功和物种形成中起着关键作用。在这方面，我们强调了最近的进展，揭示了控制这些障碍的复杂分子机制和关键参与者之间的相互作用。最近的研究揭示了控制芸薹科植物杂交障碍的分子机制。花粉外套蛋白、柱头受体和信号肽之间的相互作用在决定授粉成功方面起着至关重要的作用。在这个系统的核心，自分泌柱头 RALF 肽（sRALF）通过激活 FERONIA（FER）和 ANJEA（ANJ）受体复合物来维持柱头障碍，触发 RAC/ROP-RBOHD 途径和随后的活性氧（ROS）的产生。现在已经确定，不亲和花粉的排斥是由两条平行途径介导的：FER-RAC/ROP-RBOHD 途径产生 ROS，以及 ARC1 介导的途径降解花粉生长所需的亲和因子。相反，亲和花粉通过花粉外套蛋白（PCP-B）和旁分泌花粉衍生的 RALF 肽（pRALF）的作用克服柱头障碍，它们与自分泌 sRALF 竞争受体结合，从而使花粉成功水合和管穿透。涉及 sRALF 和 pRALF 的“锁钥”机制提供了对亲和花粉的种特异性识别。这些发现为杂交障碍的分子基础提供了有价值的见解，并为克服芸薹科内种间和属间杂交障碍开辟了新的可能性，在植物育种和作物改良方面具有潜在的应用。未来的研究应集中阐明这些信号通路的进化动态，并探索其在作物育种中的操纵。
