Stress induced F-Box protein coding gene OsFBX257 modulates drought stress adaptations and ABA responses in rice.

F-box proteins that form part of SKP1-CUL1-F-box (SCF) type of E3 ubiquitin ligases are important components of plant growth and development. Here, we characterized OsFBX257, a rice F-box protein coding gene that is differentially expressed under drought conditions and other abiotic stresses. Population genomics analysis suggest that OsFBX257 shows high allelic diversity in aus accessions and has been under positive selection in some japonica, aromatic and indica cultivars. Interestingly, allelic variation at OsFBX257 in aus cultivar Nagina22 is associated with an alternatively spliced mRNA. Conserved amongst land plants, OsFBX257 is a component of the SCF complex, can form homomers and interact molecularly with the 14-3-3 rice proteins GF14b and GF14c. OsFBX257 is co-expressed in a network involving protein kinases and phosphatases. We show that OsFBX257 can bind the kinases OsCDPK1 and OsSAPK2 and that its phosphorylation can be reversed by phosphatase OsPP2C08. OsFBX257 expression level modulates root architecture and drought stress tolerance in rice. OsFBX257 knockdown (OsFBX257 KD ) lines show reduced total root length and depth, crown root number, panicle size and survival under stress. In contrast, its over-expression (OsFBX257 OE ) increases root depth, leaf and grain length, number of panicles, and grain yield in rice. OsFBX257 is a promising breeding target for alleviating drought stress induced damage in rice. This article is protected by copyright. All rights reserved.