Overexpression of OsRRK1 Changes Leaf Morphology and Defense to Insect in Rice

Abstract

It has been reported that the receptor-like cytoplasmic kinases (RLCKs) regulate many biological processes in plants, but only a few members have been functionally characterized. Here, we isolated a rice gene encoding <i>AtRRK1</i> homology protein kinase, <i>OsRRK1</i>, which belongs to the RLCK VI subfamily. <i>OsRRK1</i> transcript accumulated in many tissues at low to moderate levels and at high levels in leaves. Overexpression of <i>OsRRK1</i> (OE-<i>OsRRK1</i>) caused adaxial rolling and erect morphology of rice leaves. In the rolled leaves of OE-<i>OsRRK1</i> plants, both the number and the size of the bulliform cells are decreased compared to the wild-type (WT) plants. Moreover, the height, tiller number, and seed setting rate were reduced in OE-<i>OsRRK1</i> plants. In addition, the brown planthopper (BPH), a devastating pest of rice, preferred to settle on WT plants than on the OE-<i>OsRRK1</i> plants in a two-host choice test, indicating that OE-<i>OsRRK1</i> conferred an antixenosis resistance to BPH. The analysis of transcriptome sequencing demonstrated that several receptor kinases and transcription factors were differentially expressed in OE-<i>OsRRK1</i> plants and WT plants. These results indicated that <i>OsRRK1</i> may play multiple roles in the development and defense of rice, which may facilitate the breeding of novel rice varieties.