The Roc10, a rice HD-Zip transcription factor gene, modulates lignin biosynthesis for drought tolerance
Ju-Kon Kim and Seung Woon Bang
Seoul National University, Korea
: J Plant Physiol Pathol
Abstract
Drought, a common environmental constraint, induces a range of physiological, biochemical and molecular changes in plants, and can cause severe reductions in crop yield. Consequently, understanding the molecular mechanisms of drought tolerance is an important step towards crop biotechnology. Here, we report that the rice (Oryza sativa) homeodomain-leucine zipper class IV transcription factor gene, Rice outermost cell-specific gene 10 (Roc10), enhances drought tolerance and grain yield by increasing lignin accumulation in ground tissues. Overexpression of Roc10 in rice significantly increased drought tolerance at the vegetative stages of growth and promoted both more effective photosynthesis and a reduction in water loss rate, compared with non-transgenic controls or RNAi transgenic plants. Importantly, Roc10 overexpressing plants had a higher drought tolerance at the reproductive stage of growth and a higher grain yield compared with the controls under field-drought conditions. Roc10 is mainly expressed in outer cell layers including the epidermis and the vasculature of the shoots, which coincides with areas of cell wall lignification. Roc10 overexpression elevated the expression levels of lignin biosynthetic genes in shoots, with a concomitant increase in the accumulation of lignin, while the overexpression and RNAi lines showed opposite patterns of lignin accumulation. We identified downstream target genes of Roc10 by performing RNA-sequencing and chromatin immunoprecipitation (ChIP)-sequencing analyses of shoot tissues. Roc10 was found to directly bind to the promoter of Peroxidasen/peroxidase38, a key gene in lignin biosynthesis. Together, our findings suggest that Roc10 confers drought stress tolerance by promoting lignin biosynthesis in ground tissues.
Biography
Ju-Kon Kim is a Professor in Graduate School of International Agricultural Technology, Seoul National University. He is the Director of Crop Biotechnology Institute, where he worked since 2013. He has obtained his PhD in Plant Molecular Biology in 1992 at Cornell University of USA. His current research is concentrated on discovering novel genes for drought tolerance of rice with special attention to crop biotechnology by integrating genomics and phenomics approaches, characterizing key regulators in stress tolerance.
