Overexpression of OsTF1L, a rice HD-Zip transcription factor, promotes lignin biosynthesis and stomatal closure that improves drought tolerance

First author: Seung Woon Bang; Affiliations: Seoul National University (首尔国立大学): Pyeongchang, Korea

Corresponding author: Ju‐Kon Kim

Drought stress seriously impacts on plant development and productivity. Improvement of drought tolerance without yield penalty is a great challenge in crop biotechnology. Here, we report that the rice (Oryza sativa) homeodomain‐leucine zipper transcription factor gene, OsTF1L (Oryza sativatranscription factor 1‐like), is a key regulator of drought tolerance mechanisms. Overexpression of the OsTF1L in rice significantly increased drought tolerance at the vegetative stages of growth and promoted both effective photosynthesis and a reduction in the water loss rate under drought conditions. Importantly, the OsTF1L overexpressing plants showed a higher drought tolerance at the reproductive stage of growth with a higher grain yield than non‐ ransgenic controls under field‐drought conditions. Genome‐wide analysis of OsTF1L overexpression plants revealed up‐r egulation of drought‐inducible, stomatal movement (气孔运动) and lignin biosynthetic genes. Overexpression of OsTF1L promoted accumulation of lignin in shoots, whereas the RNAi lines showed opposite patterns of lignin accumulation. OsTF1L is mainly expressed in outer cell layers including the epidermis (表皮), and the vasculature (维管) of the shoots, which coincides with areas of lignification. In addition, OsTF1L overexpression enhances stomatal closure under drought conditions resulted in drought tolerance. More importantly, OsTF1L directly bound to the promoters of lignin biosynthesis and drought‐r elated genes involving poxN/PRX38, Nodulin protein, DHHC4, CASPL5B1 and AAA‐ ype ATPase. Collectively, our results provide a new insight into the role of OsTF1L in enhancing drought tolerance through lignin biosynthesis and stomatal closure in rice.

干旱胁迫会严重制约植物的发育和生殖。在不影响作物产量的前提下提升干旱抗性是作物育种中的重要挑战。本文报道了水稻HD-Zip转录因子基因OsTF1L是介导干旱抗性的重要调控子。水稻过表达OsTF1L基因会显著增加营养生长阶段的干旱抗性，并促进光合作用和减少干旱条件下的水分的流失。重要的是，OsTF1L过表达植株在生殖生长阶段具有更高的干旱抗性，同时在干旱条件下较野生型的产量更高。OsTF1L过表达植株与野生型相比，与干旱诱导、气孔运动及木质素生物合成相关基因上调表达。过表达OsTF1L基因增加木质素在地上组织中的积累，而RNAi干扰株系则表现出完全相反的木质素积累模式。OsTF1L基因主要在外层细胞表达，比如表皮细胞，地上部分的维管组织，这与木质化的部位一致。另外，OsTF1L基因过表达会在干旱条件下增强气孔的关闭，进而提升植物的干旱抗性。更加重要的是，OsTF1L直接结合到木质素生物合成和干旱相关基因的上游启动子区，比如poxN/PRX38、Nodulin protein、DHHC4、CASPL5B1和AAA‐ ype ATPase。综上，本文的结果揭示了OsTF1L通过木质素生物合成和气孔关闭来增强水稻的干旱抗性。

doi: https://doi.org/10.1111/pbi.12951

Journal: Plant Biotechnology Journal

First Published date: 21 May, 2018

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