A WUSCHEL Homeobox Transcription Factor, OsWOX13, Enhances Drought Tolerance and Triggers Early Flowering in Rice.

Abstract

Plants have evolved strategies to cope with drought stress by maximizing physiological capacity and adjusting developmental processes such as flowering time. The WOX13 orthologous group is the most conserved among the clade of WOX homeodomain-containing proteins and is found to function in both drought stress and flower development. In this study, we isolated and characterized <i>OsWOX13</i> from rice. <i>OsWOX13</i> was regulated spatially in vegetative organs but temporally in flowers and seeds. Overexpression of <i>OsWOX13</i> (OsWOX13-ov) in rice under the rab21 promoter resulted in drought resistance and early flowering by 7-10 days. Screening of gene expression profiles in mature leaf and panicles of OsWOX13-ov showed a broad spectrum of effects on biological processes, such as abiotic and biotic stresses, exerting a cross-talk between responses. Protein binding microarray and electrophoretic mobility shift assay analyses supported ATTGATTG as the putative <i>cis</i>-element binding of OsWOX13. <i>OsDREB1A</i> and <i>OsDREB1F</i>, drought stress response transcription factors, contain ATTGATTG motif(s) in their promoters and are preferentially expressed in OsWOX13-ov. In addition, <i>Heading date 3a</i> and Os<i>MADS14</i>, regulators in the flowering pathway and development, were enhanced in OsWOX13-ov. These results suggest that <i>OsWOX13</i> mediates the stress response and early flowering and, thus, may be a regulator of genes involved in drought escape.