RT Journal Article SR Electronic T1 Fitness benefit plays a vital role in the retention of the Pi-ta susceptible alleles JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.30.229831 DO 10.1101/2020.07.30.229831 A1 Jia Liu A1 Yue Wang A1 Suobing Zhang A1 Fan Wu A1 Long Wang A1 Jiayu Xue A1 Yanmei Zhang A1 Pengfei Xie A1 Yueyu Hang A1 Xiaoqin Sun YR 2020 UL http://biorxiv.org/content/early/2020/07/31/2020.07.30.229831.abstract AB In plants, large numbers of R genes, which segregate as loci with alternative alleles conferring different resistance to pathogens, have been maintained over a long evolutionary time. In theory, there seem to be no reason for hosts to harbor these susceptible alleles in view of their null contribution to resistance. As such, why should populations support disease-susceptible individuals along with disease-resistant individuals? In rice, a single copy R gene Pi-ta segregates for two expressed clades of alleles, one resistant and the other susceptible. We discovered that knockout of the Pi-ta susceptible alleles induced drastic fitness decline in the absence of pathogens. Gene expression profiling and endogenous hormones quantification showed that the susceptible alleles might serve as an off-switch to the downstream immune signaling, thus contributing to fine-tuning of plant defense response. The fitness benefit of carrying a susceptible Pi-ta allele provides a plausible explanation for their retention in the genome.Competing Interest StatementThe authors have declared no competing interest.