AUTHOR=Yamatani Hiroshi , Heng Titnarong , Yamada Tetsuya , Kusaba Makoto , Kaga Akito 

TITLE=Identification and Characterization of an Early Leaf Senescence Gene ELS1 in Soybean

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.784105

DOI=10.3389/fpls.2021.784105

ISSN=1664-462X

ABSTRACT=<p>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, <italic>els1-1</italic> (<italic><underline>e</underline>arly <underline>l</underline>eaf <underline>s</underline>enescence <underline>1</underline></italic>) and <italic>els1-2.</italic> The chlorophyll contents of both <italic>els1-1</italic> and <italic>els1-2</italic> were low in pre-senescent leaves. They degraded rapidly in senescent leaves, revealing that <italic>ELS1</italic> is involved in chlorophyll biosynthesis during leaf development and chlorophyll degradation during leaf senescence. The causal mutations in <italic>els1</italic> were identified by next-generation sequencing-based bulked segregant analysis. <italic>ELS1</italic> encodes the ortholog of the <italic>Arabidopsis</italic> CaaX-like protease BCM1, which is localized in chloroplasts. Soybean <italic>ELS1</italic> was highly expressed in green tissue, especially in mature leaves. The accumulation of photosystem I core proteins and light-harvesting proteins in <italic>els1</italic> was low even in pre-senescent leaves, and their degradation was accelerated during leaf senescence. These results suggest that soybean <italic>ELS1</italic> is involved in both chlorophyll synthesis and degradation, consistent with the findings in <italic>Arabidopsis</italic> BCM1. The gene <italic>els1,</italic> characterized by early leaf senescence and subsequent early maturation, does not affect the flowering time. Hence, the early leaf senescence trait regulated by <italic>els1</italic> helps shorten the harvesting period because of early maturation characteristics. The <italic>els1-1</italic> allele with weakly impaired function of <italic>ELS1</italic> has only a small effect on agricultural traits and could contribute to practical breeding.</p>