Biotechnology Center, National Chung Hsing University, Taichung, 402, Taiwan, ROC.
C4 Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines.
Plant Cell Rep. 2022 Feb;41(2):319-335. doi: 10.1007/s00299-021-02810-5. Epub 2021 Nov 27.
Elevated expression of nucleotide-binding and leucine-rich repeat proteins led to closer vein spacing and higher vein density in rice leaves. To feed the growing global population and mitigate the negative effects of climate change, there is a need to improve the photosynthetic capacity and efficiency of major crops such as rice to enhance grain yield potential. Alterations in internal leaf morphology and cellular architecture are needed to underpin some of these improvements. One of the targets is to generate a "Kranz-like" anatomy in leaves that includes decreased interveinal spacing close to that in C plant species. As C photosynthesis has evolved from C photosynthesis independently in multiple lineages, the genes required to facilitate C may already be present in the rice genome. The Taiwan Rice Insertional Mutants (TRIM) population offers the advantage of gain-of-function phenotype trapping, which accelerates the identification of rice gene function. In the present study, we screened the TRIM population to determine the extent to which genetic plasticity can alter vein density (VD) in rice. Close vein spacing mutant 1 (CVS1), identified from a VD screening of approximately 17,000 TRIM lines, conferred heritable high leaf VD. Increased vein number in CVS1 was confirmed to be associated with activated expression of two nucleotide-binding and leucine-rich repeat (NB-LRR) proteins. Overexpression of the two NB-LRR genes individually in rice recapitulates the high VD phenotype, due mainly to reduced interveinal mesophyll cell (M cell) number, length, bulliform cell size and thus interveinal distance. Our studies demonstrate that the trait of high VD in rice can be achieved by elevated expression of NB-LRR proteins limited to no yield penalty.
核苷酸结合和富含亮氨酸重复蛋白的表达水平升高导致水稻叶片的叶脉间距变近,叶脉密度增加。为了养活不断增长的全球人口并减轻气候变化的负面影响,需要提高水稻等主要作物的光合作用能力和效率,以提高粮食产量潜力。需要改变内部叶片形态和细胞结构来支撑其中的一些改进。目标之一是在叶片中产生类似于“Kranz”的解剖结构,包括靠近 C 植物物种的叶脉间距减小。由于 C 光合作用是在多个谱系中独立从 C 光合作用进化而来的,因此促进 C 的所需基因可能已经存在于水稻基因组中。台湾水稻插入突变体(TRIM)群体具有功能获得表型捕获的优势,这加速了水稻基因功能的鉴定。在本研究中,我们筛选了 TRIM 群体,以确定遗传可塑性在多大程度上可以改变水稻的叶脉密度(VD)。从大约 17000 条 TRIM 线的 VD 筛选中鉴定出的紧密叶脉间距突变体 1(CVS1)赋予了水稻叶片可遗传的高 VD。CVS1 中叶脉数量的增加被确认为与两个核苷酸结合和富含亮氨酸重复(NB-LRR)蛋白的激活表达有关。NB-LRR 基因在水稻中的过表达单独再现了高 VD 表型,主要是由于间生细胞(M 细胞)数量、长度、泡状细胞大小和因此间生距离减少。我们的研究表明,通过 NB-LRR 蛋白的表达升高可以实现水稻高 VD 的特性,而不会带来产量损失。