Abstract
BackgroundRice 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.ResultsWe 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.ConclusionCollectively, 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.
Highlights
Rice productivity is adversely affected by environmental stresses
Salinity stress has been documented to induce a set of Saltol QTL-localized genes including Histone gene binding protein/transcription factor-1b (HBP1b) which is differentially expressed among the contrasting genotypes of rice (Kumari et al 2009)
Nuclear-localized bZIP transcription factor OsHBP1b exhibits developmental regulation and differential expression under diverse abiotic stresses In our previous study, we have shown that OsHBP1b is a bZIP type protein and is very much related to its orthologs from wheat and barley (Lakra et al 2015)
Summary
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. The molecular response of plants towards these stresses has been reported to be highly complex; an interplay of many genes involved in perception and signal transduction (Pareek et al 2010). Among these genes, the transcription factors (TFs) have been reported as key players in determining the survival and yield of plants under stress conditions Salinity stress has been documented to induce a set of Saltol QTL-localized genes including Histone gene binding protein/transcription factor-1b (HBP1b) which is differentially expressed among the contrasting genotypes of rice (Kumari et al 2009)
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