异源三聚体G蛋白亚基调控水稻叶肉CO2电导和耐旱性

今天介绍的是美国科学家最新发表在《New Phyto》的研究论文《The α subunit of the heterotrimeric G protein regulates mesophyll CO2 conductance and drought tolerance in rice》。

叶肉电导 (gm) 决定了从叶肉细胞间隙到叶绿体的 CO2 扩散速率，是限制光合作用的重要因素。增加栽培植物gm是提高光合作用和水分利用效率 (WUEi) 的潜在策略。叶的解剖结构和代谢因子如水通道蛋白和碳酸酐酶已被确定为 gm 的重要决定因素。然而，参与gm调控的基因在很大程度上仍然未知。

在这项工作中，作者在水稻突变体di中，研究了异源三聚体G蛋白在gm和干旱胁迫中的功能。该突变体在G亚基基因RGA1中具有无效突变。

与野生型相比，日本晴和台中65 品种的d1突变体表现出增加的 gm，促进光合作用、WUEi 和耐旱性的改善。暴露于细胞间隙的叶肉细胞和叶绿体表面积的增加，以及d1突变体中细胞壁和叶绿体厚度的减少是gm增加的明显原因。

作者的结果表明，操纵异源三聚体G蛋白信号具有提高干旱条件下作物WUEi 和产量的潜力。

Mesophyll conductance (gm) determines CO2 diffusion rates from mesophyll intercellular air spaces to the chloroplasts and is an important factor limiting photosynthesis. Increasing gm in cultivated plants is a potential strategy to increase photosynthesis and water use efficiency (WUEi). The anatomy of the leaf and metabolic factors such as aquaporins and carbonic anhydrases have been identified as important determinants of gm. However, genes involved in the regulation and modulation of gm remain largely unknown.

In this work, we investigated the role of heterotrimeric G proteins in gm and drought tolerance in rice d1 mutants, which harbor a null mutation in the Gα subunit gene, RGA1.

d1 mutants in both Nipponbare and Taichung 65 cultivars exhibited increased gm, fostering improvement in photosynthesis, WUEi, and drought tolerance compared to wild type. The increased surface area of mesophyll cells and chloroplasts exposed to intercellular airspaces, and reduced cell wall and chloroplast thickness in the d1 mutant are evident contributors to the increase in gm.

Our results indicate that manipulation of heterotrimeric G protein signaling has the potential to improve crop WUEi and productivity under drought.