Das Priyanka, Lakra Nita, Nutan Kamlesh Kant, Singla-Pareek Sneh Lata, Pareek Ashwani
Stress Physiology and Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
Plant Stress Biology, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Road, New Delhi, 110067, India.
Rice (N Y). 2019 Aug 2;12(1):58. doi: 10.1186/s12284-019-0316-8.
Rice productivity is adversely affected by environmental stresses. Transcription factors (TFs), as the regulators of gene expression, are the key players contributing to stress tolerance and crop yield. Histone gene binding protein-1b (OsHBP1b) is a TF localized within the Saltol QTL in rice. Recently, we have reported the characterization of OsHBP1b in relation to salinity and drought tolerance in a model system tobacco. In the present study, we over-express the full-length gene encoding OsHBP1b in the homologous system (rice) to assess its contribution towards multiple stress tolerance and grain yield.
We provide evidence to show that transgenic rice plants over-expressing OsHBP1b exhibit better survival and favourable osmotic parameters under salinity stress than the wild type counterparts. These transgenic plants restricted reactive oxygen species accumulation by exhibiting high antioxidant enzyme activity (ascorbate peroxidase and superoxide dismutase), under salinity conditions. Additionally, these transgenic plants maintained the chlorophyll concentration, organellar structure, photosynthesis and expression of photosynthesis and stress-related genes even when subjected to salinity stress. Experiments conducted for other abiotic stresses such as drought and high temperature revealed improved tolerance in these transgenic plants with better root and shoot growth, better photosynthetic parameters, and enhanced antioxidant enzyme activity, in comparison with WT. Further, the roots of transgenic lines showed large cortical cells and accumulated a good amount of callose, unlike the WT roots, thus enabling them to penetrate hard soil and prevent the entry of harmful ions in the cell.
Collectively, our results show that rice HBP1b gene contributes to multiple abiotic stress tolerance through several molecular and physiological pathways and hence, may serve as an important gene for providing multiple stress tolerance and improving crop yield in rice.
水稻生产力受到环境胁迫的不利影响。转录因子作为基因表达的调节因子，是有助于提高胁迫耐受性和作物产量的关键因素。组蛋白基因结合蛋白-1b（OsHBP1b）是水稻中位于Saltol QTL内的一种转录因子。最近，我们报道了在模式系统烟草中对OsHBP1b与盐度和耐旱性相关的特性进行的表征。在本研究中，我们在同源系统（水稻）中过表达编码OsHBP1b的全长基因，以评估其对多种胁迫耐受性和谷物产量的贡献。
我们提供的证据表明，过表达OsHBP1b的转基因水稻植株在盐胁迫下比野生型植株表现出更好的存活率和有利的渗透参数。在盐度条件下，这些转基因植株通过表现出高抗氧化酶活性（抗坏血酸过氧化物酶和超氧化物歧化酶）来限制活性氧的积累。此外，即使受到盐胁迫，这些转基因植株仍能维持叶绿素浓度、细胞器结构、光合作用以及光合作用和胁迫相关基因的表达。对干旱和高温等其他非生物胁迫进行的实验表明，与野生型相比，这些转基因植株具有更好的耐受性，根和茎的生长更好，光合参数更佳，抗氧化酶活性增强。此外，与野生型根不同，转基因系的根显示出大的皮层细胞并积累了大量的胼胝质，从而使它们能够穿透坚硬的土壤并防止有害离子进入细胞。
总体而言，我们的结果表明，水稻HBP1b基因通过多种分子和生理途径对多种非生物胁迫耐受性有贡献，因此，它可能是一个重要基因，可用于提高水稻的多种胁迫耐受性和作物产量。
