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 receptorlike 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.

Overexpression of Rice Expansin7 (Osexpa7) Confers Enhanced Tolerance to Salt Stress in Rice

“…WAKs have been widely investigated as potential cell wall "sensors," and they play important roles in cell expansion [49]. RNAi-mediated silencing OsiWAK1 showed a decrease in plant size due to a reduction in cell size, but not cell number [50]. In DEG analysis, OsWAK1 showed more than two-fold upregulation (3.93) in OsEXPA7-OX plants, which was confirmed by qRT-PCR results ( Figure 10D).…”

Action of multiple intra-QTL genes concerted around a co-localized transcription factor underpins a large effect QTL

“…Ten of these genes (containing the central yellow dot in Figure S9 ) were chosen for further analysis due to either putatively direct regulation by OsNAM 12.1 or a direct link to strongly inducible drought responsive transcription factors ( Figure S9 ). The gene OsWAK 12.1 was an exception and was chosen based on strong evidence from the literature for its function highly relevant to stress tolerance 20 . Nine of these 10 genes spread along qDTY 12.1 were finally used as gene-based markers in combination with the five original SSR markers to ensure marker collinearity at an average marker distance of about 0.2 cM for high-density mapping ( Fig.…”

“…Similarly, an Arabidopsis Gram Domain Protein (GDP; a likely ortholog of OsGDP 12.1 ) was shown to be ABA- and stress-responsive and affected reproductive development 60 . A rice homolog of OsWAK 12.1 was also associated with female gametophyte development 61 , while silencing of another OsWAK led to abnormal root development and anther indehiscence 20 . OsPOEI19 12.1 has high similarity to an Arabidopsis ortholog (AT5GO5500) that is known to be functional in root hair elongation, while the cell wall forming cellulose synthases similar to OsCesA10 12.1 are also known to be functional in root and root hair development 62 .…”

Expression of OsMYB55 in maize activates stress-responsive genes and enhances heat and drought tolerance

“…WAKs can function as links between intracellular compartments and the extracellular environment and are thought to have a role in cell elongation, development and stress responses [ 46 ]. Down-regulation of WAK1 in rice affects root growth and produces dwarf plants and male sterility [ 47 ] whereas in barley it also affects root phenotypes in plants grown under control and stress conditions [ 48 ]. Other group of up-regulated genes in OsMYB55 maize may be more implicated in responses to oxidative stress, such as two lipid transfer proteins (LTPs, AC194203.3_FG003 and AC155352.2_FG010).…”