RNAi mediated silencing of a wall associated kinase, OsiWAK1 in Oryza sativa results in impaired root development and sterility due to anther indehiscence

Abstract

The Wall-Associated Kinase, one of the receptor-like kinase (RLK) gene families in plant, plays important roles in cell expansion, pathogen resistance and heavy metal stress tolerance in Arabidopsis thaliana. Here, we isolated a cDNA encoding a novel WAK from indica rice and designated as OsiWAK1 (Oryza sativa indica WAK-1). In this study, the RNAi construct with OsiWAK1 gene cloned in sense and antisense orientation separated by a functional intron under constitutive promoter, was introduced through biolistic gene gun method into the rice cultivar "IR-50" to determine the effect of OsiWAK1 transcript silencing on rice plant development. Examination of the transgenic plants reveals that OsiWAK1 transcript silencing in rice results in dwarf plants because of the reduction in the size of leaves, flag-leaves, internodes and panicle. The development of root primordia during germination, root hairs and lateral rooting was also effected. Microscopic analysis revealed that the decrease in size is due to reduction in the cell size but not the number of cells. In addition, the transgenic plants also exhibited sterile phenotype due to anther indehiscence and 40% reduction in pollen viability. These data suggest that OsiWAK1 may play an important role in rice plant growth and development.