Background

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.

Results

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.

Conclusion

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.

中文翻译：

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独特的bZIP转录因子赋予水稻多重胁迫耐受性。

背景

水稻生产力受到环境压力的不利影响。转录因子（TFs）作为基因表达的调节剂，是导致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）是位于水稻Saltol QTL中的TF 。最近，我们已经报道了在模型系统烟草中与盐度和耐旱性相关的OsHBP1b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，以评估其对多重胁迫耐受性和谷物产量的贡献。

结果

我们提供证据表明过表达OsHBP1b的转基因水稻植物与野生型相比，在盐分胁迫下显示出更好的存活率和有利的渗透参数。这些转基因植物在盐分条件下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），从而限制了活性氧的积累。另外，这些转基因植物即使在盐分胁迫下也能维持叶绿素浓度，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。针对其他非生物胁迫（例如干旱和高温）进行的实验表明，与WT相比，这些转基因植物具有更好的耐受性，具有更好的根和茎生长，更好的光合参数和增强的抗氧化酶活性。进一步，

结论

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促进了多种非生物胁迫耐受性，因此，它可能是提供多重胁迫耐受性和提高水稻产量的重要基因。