Optimising plant resilience to abiotic and biotic stresses through improved silicon absorption

本提案的主要目的是确定植物吸收硅（Si）的分子机制，并将这些发现应用于提高植物在恶劣农业条件下的抗逆性。它基于一个公认的前提，即硅积累保护植物免受各种非生物和生物胁迫。这些好处在表达专门的硅吸收转运系统的植物中更具体地观察到。其中一个系统是内流转运蛋白1 (Lsi1)，它是水通道蛋白家族的一种NIP-III，可促进硅在根细胞的外表皮和内胚层表面内流。另一个系统，外排转运体2 (Lsi2)，一种假定的阴离子转运体，促进硅在相同细胞中的外排。通过最近对Lsi1和Lsi2突变体的Si转运特性的结构-功能研究，我们发现特定的氨基酸序列和结构模式赋予了不同同源物之间的差异。通过鉴定Lsi1和Lsi2的完整序列，并利用非洲爪蟾的异源表达系统筛选这些转运体，将有可能测试数百个突变体或筛选尽可能多的自然变异体，并选择最有希望调节植物硅积累能力的突变体。从这些研究中获得的见解将应用于生产气候变化，即抗旱和抗病植物。

The main objective of this proposal is to identify the molecular mechanisms of silicon (Si) absorption by plant species and to apply these findings towards improving plant resilience under harsh agricultural conditions. It rests on the well-established premise that Si accumulation protects plants against a variety of abiotic as well as biotic stresses. These benefits are more specifically observed in plants that express dedicated Si transport systems for Si uptake. One of these systems, the influx transporter 1 (Lsi1), a NIP-III from the aquaporin family, promotes Si influx across the exodermal and endodermal surfaces of root cells. The other system, the efflux transporter 2 (Lsi2), a putative anion transporter, promotes Si efflux across the same cells. Through recent structure-function studies in which the Si transport properties of Lsi1 and Lsi2 mutants were examined ,we have discovered that specific amino acid sequences and structural patterns confer differences among the various orthologs. By having identified the complete sequences of Lsi1 and Lsi2 and by using the heterologous expression system of Xenopus laevis to screen for such transporters, it will be possible to test hundreds of mutants or screen as many natural variants and to select the most promising ones for their ability to modulate Si accumulation in plants. Insights gained from such studies will be applied towards the production of climate-change i.e. drought and disease-resistant plants.