Yamatani Hiroshi, Heng Titnarong, Yamada Tetsuya, Kusaba Makoto, Kaga Akito
Institute of Crop Science, National Agriculture and Food Research Organization, Tsukuba, Japan.
Department of Agronomy, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Kamphaeng Saen, Thailand.
Front Plant Sci. 2021 Dec 16;12:784105. doi: 10.3389/fpls.2021.784105. eCollection 2021.
Early leaf senescence phenotype in soybean could be helpful to shorten the maturation period and prevent green stem disorder. From a high-density mutation library, we identified two early leaf senescence soybean mutant lines, () and The chlorophyll contents of both and were low in pre-senescent leaves. They degraded rapidly in senescent leaves, revealing that is involved in chlorophyll biosynthesis during leaf development and chlorophyll degradation during leaf senescence. The causal mutations in were identified by next-generation sequencing-based bulked segregant analysis. encodes the ortholog of the CaaX-like protease BCM1, which is localized in chloroplasts. Soybean was highly expressed in green tissue, especially in mature leaves. The accumulation of photosystem I core proteins and light-harvesting proteins in was low even in pre-senescent leaves, and their degradation was accelerated during leaf senescence. These results suggest that soybean is involved in both chlorophyll synthesis and degradation, consistent with the findings in BCM1. The gene characterized by early leaf senescence and subsequent early maturation, does not affect the flowering time. Hence, the early leaf senescence trait regulated by helps shorten the harvesting period because of early maturation characteristics. The allele with weakly impaired function of has only a small effect on agricultural traits and could contribute to practical breeding.
大豆早期叶片衰老表型可能有助于缩短成熟期并预防绿茎病。从一个高密度突变文库中，我们鉴定出两个早期叶片衰老的大豆突变系，（）和。在衰老前叶片中，和的叶绿素含量均较低。它们在衰老叶片中迅速降解，表明在叶片发育过程中参与叶绿素生物合成，在叶片衰老过程中参与叶绿素降解。通过基于下一代测序的混合分离群体分析鉴定出中的因果突变。编码CaaX样蛋白酶BCM1的直系同源物，该蛋白酶定位于叶绿体中。大豆在绿色组织中高度表达，尤其是在成熟叶片中。即使在衰老前叶片中，中光系统I核心蛋白和捕光蛋白的积累也很低，并且在叶片衰老过程中它们的降解加速。这些结果表明大豆既参与叶绿素合成又参与叶绿素降解，这与BCM1中的发现一致。以早期叶片衰老和随后的早熟为特征的基因，不影响开花时间。因此，由调控的早期叶片衰老性状由于早熟特性有助于缩短收获期。功能受损较弱的等位基因对农艺性状只有很小的影响，并且可能有助于实际育种。
