LAUSR

Weedy rice is a weed relative of cultivated rice with strong drought resistance that propagates in paddy fields. In this paper, five hundred and one rice accessions were used to reveal the selection mechanism of drought resistance in weedy rice through selection analysis, genome-wide association study, gene knockout and overexpression analysis and Ca 2+ and K + ion flux assay. Results showed the weedy rice species investigated have gene introgression with cultivated rice, which is consistent with the hypothesis weedy rice originated from de-domestication of cultivated rice. Regions related to tolerance are particularly targeted during de-domestication and three drought-tolerance genes were identified, among them, Os01g0800500 gene was identified again using leaf withering degree and named PAPH1. The drought resistance capacity of PAPH1 knockout lines was much weaker than that of wild ecotypes, while that of overexpression lines was much stronger than that of wild ecotypes. Concentrations of Ca 2+ and K + were lower in the knockout mutant and higher in the overexpression line compared with those of wild type, which suggested that PAPH1 plays important roles in coping with drought stress. This study will initiate novel project in discovering new resistance genes and provide new insights in understanding genetic mechanisms underlying adaptive tolerance.