View related articles View Crossmark data Citing articles: 1 View citing articles Effect of drought acclimation on oxidative stress and transcript expression in wheat (Triticum aestivum L.

Plant U-box E3 ubiquitin ligase (PUB) is involved in various environmental stress conditions. However, the molecular mechanism of U-box proteins in response to abiotic stress in wheat remains unknown. In this study, two U-box E3 ligase genes (TaPUB2 and TaPUB3), which are highly expressed in response to adverse abiotic stresses, were isolated from common wheat, and their cellular functions were characterized under drought stress. Transient expression assay revealed that TaPUB2 was localized in the cytoplasm and Golgi apparatus, whereas TaPUB3 was expressed only in the Golgi apparatus in wheat protoplasts. Additionally, TaPUB2 and TaPUB3 underwent self-ubiquitination. Moreover, TaPUB2/TaPUB3 heterodimer was identified in yeast and the cytoplasm of wheat protoplasts using a pull-down assay and bimolecular fluorescence complementation analysis. Heterogeneous overexpression of TaPUB2 and TaPUB3 conferred tolerance to drought stress. Taken together, these results implied that the heterodimeric form of U-box E3 ubiquitin ligases (TaPUB2/TaPUB3) responded to abiotic stress and roles as a positive regulator of drought stress tolerance.

Sorghum [Sorghum bicolor (L.) Moench] is considered as an important staple crop in the tropical regions. However, the productivity of this useful crop is hindered by drought which contributes to significant yield reduction. The present study aimed to decipher the effects of drought stress on physiological, biochemical and gene expression changes in sorghum genotypes and to ascertain the differences in their response to drought stress. To achieve these objectives, six sorghum genotypes were grown in pot culture in a greenhouse, in a randomized complete block design and exposed to water stress treatment for 10 days. From the study, drought stress caused a significant (P < .05) reduction in plant height, leaf water and chlorophyll contents while the proline, malondialdehyde (MDA), soluble sugar, electrolyte leakage (EL), hydrogen peroxide (H2O2) and antioxidant enzymes activity increased significantly (P < .05) and differentially in all sorghum genotypes. Among the genotypes investigated, PI 585456 showed enhanced performance and was considered as the most tolerant to drought in relation to plant growth and water relation, membrane status, photosynthetic activity, ROS and osmolytes accumulation and antioxidant enzymes activity. Furthermore, the transcript expression analyses of different categories of drought-responsive genes, viz; antioxidant-related, osmolytes biosynthesis-related, dehydrin-related, photosystem-related and transcription-related were differentially upregulated in sorghum genotypes investigated. The results revealed the differences in metabolic response to drought among the genotypes, which accentuated the physiological, biochemical and molecular mechanism related to a specific response that may play a vital role in drought tolerance in sorghum.

Plant U‐box E3 ligases (PUBs) are important regulators of responses to various abiotic stress conditions. In this study, we found that wheat (Triticum aestivum. L) PUBs TaPUB2 and TaPUB3 enhanced abscisic acid (ABA) responses and salt tolerance in Arabidopsis. We generated transgenic Arabidopsis lines overexpressing TaPUB2 and TaPUB3 and performed various plant physiological experiments. Overexpression of TaPUB2 and TaPUB3 increased tolerance to salinity stress in an ABA‐dependent manner in transgenic plants, as evidenced by germination and survival rates, root length, stomatal aperture regulation, membrane peroxidation, photosynthetic activities, reactive oxygen species scavenging activities and expression of various ABA and salinity stress‐related genes. These results demonstrate the functions of PUBs under ABA and salinity stress conditions and provide valuable information for the development of salinity stress‐tolerant crop species.

No abstract