As sessile organisms, plant must be capable of adapting to various environmental signals. The understanding of how crops sense and respond to ambient temperature changes is crucial for sustainable agriculture. In rice, thermosensitive genic male-sterile lines (TGMS) lines have been extensively utilized to increase rice grain yield in two-line hybrid system. Rice TGMS lines, male-sterile at restrictive (high) temperatures but male-fertile at permissive (low) temperatures, also provide a good system to understand how plants sense and respond to changing ambient temperature. However, the underlying mechanism of TGMS has not been fully elucidated.
A recent study, delivered by Dr. LI Yunhai's team from the Institute of Genetics and Developmental Biology (IGDB) of the Chinese Academy of Sciences (CAS), has revealed the important roles of a single amino acid L301P mutation of the histone binding protein OsMS1 (MALE STERILITY 1) in responding to temperature changes and confers thermosensitive genic male sterility in rice.
Notably, the L301P mutation maps the highly conserved LXXLL motif (L is leucine and X is any amino acid) that was known to play roles in protein-protein interactions and protein subcellular localization.
To further understand why the L301P mutation in OsMS1 contributes to the temperature-sensitive male sterile phenotype, the authors proposed a most likely explanation that OsMS1 can function in both low and high temperatures, while OsMS1wenmin1 is functional in low temperature but not high temperature.
They then proposed an idea that ambient temperature might regulate protein abundance of green fluorescent protein (GFP)-OsMS1 and GFP-OsMS1wenmin1, and that GFP-OsMS1wenmin1 might be more sensitive to temperature changes than OsMS1. Consistently, the authors demonstrated the temperature-dependent protein abundance using serial careful experimental design.
They also identified basic helix-loop-helix transcription factor TDR (TAPETUM DEGENERATION RETARDATION) as OsMS1 interacting protein to explore how OsMS1 could regulate male fertility, and how the L301P mutation in OsMS1 could abolish its function in high temperature. They found that the interactions of OsMS1 and OsMS1wenmin1 with TDR were also temperature-dependent, possibly due to the temperature-dependent protein abundance of OsMS1 and OsMS1wenmin1.
Collectively, this study identified the first tissue-specific temperature-sensing mechanism in plants. Given the fact that OsMS1 and its homolog genes are shared in monocot and dicot species, and the Leu301 is evolutionarily conserved in OsMS1 and its homologs. This study also opens a perspective to create new TGMS lines by generating the L301P mutation in various rice cultivars, and even other plant species using genome editing technology.
This study was published in Nature Communications
on April 19 as a featured article as well as the editors' highlights webpage
and it was supported by the Strategic Priority Research Program of CAS and the National Natural Science Foundation of China.
Proposed working model for OsMS1-mediated thermosensitive mechanism (Image by IGDB)