Genome-Wide Identification and Analysis of bZIP Gene Family and Resistance of TaABI5 (TabZIP96) under Freezing Stress in Wheat (Triticum aestivum).

The basic leucine zipper (bZIP) regulates plant growth and responds to stress as a key transcription factor of the Abscisic acid (ABA) signaling pathway. In this study, TabZIP genes were identified in wheat and the gene structure, physicochemical properties, cis-acting elements, and gene collinearity were analyzed. RNA-Seq and qRT-PCR analysis showed that ABA and abiotic stress induced most TabZIP genes expression. The ectopic expression of TaABI5 up-regulated the expression of several cold-responsive genes in Arabidopsis. Physiological indexes of seedlings of different lines under freezing stress showed that TaABI5 enhanced the freezing tolerance of plants. Subcellular localization showed that TaABI5 is localized in the nucleus. Furthermore, TaABI5 physically interacted with cold-resistant transcription factor TaICE1 in yeast two-hybrid system. In conclusion, this study identified and analyzed members of the TabZIP gene family in wheat. It proved for the first time that the gene TaABI5 affected the cold tolerance of transgenic plants and was convenient for us to understand the cold resistance molecular mechanism of TaABI5. These results will provide a new inspiration for further study on improving plant abiotic stress resistance.

tae-miR399-UBC24 Module Enhances Freezing Tolerance in Winter Wheat via a CBF Signaling Pathway.

Although the regulation of Pi homeostasis by miR399 has been studied in various plant species, its underlying molecular mechanism in response to freezing stress is still poorly understood. In this work, we found that the expression of tae-miR399 and its target gene TaUBC24 in the tillering nodes of the strong cold-resistant winter wheat cultivar Dongnongdongmai1 (Dn1) was not only significantly altered after severe winters but also responsive to short-term freezing stress. TaUBC24 physically interacted with TaICE1. Enhanced freezing tolerance was observed for tae-miR399-overexpressing Arabidopsis lines. Under freezing stress, overexpression of tae-miR399 ultimately decreased the expression of AtUBC24, inhibiting the degradation of AtICE1, which increased the expression of genes involved in the CBF signaling pathway and starch metabolism and promoted the activities of antioxidant enzymes. These results will improve our understanding of the molecular mechanism through which the miR399-UBC24 module plays a cardinal role in regulating plant freezing stress tolerance through mediation of downstream pathways.

Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase genes of winter wheat enhance the cold tolerance of transgenic Arabidopsis.

In this study, winter wheat G6PDH (TaG6PDH) and 6PGDH (Ta6PGDH) were investigated. Both their expression and their activity were upregulated under cold stress, suggesting that TaG6PDH and Ta6PGDH positively respond to cold stress in winter wheat. Exogenous abscisic acid (ABA) treatment markedly increased the expression and activity levels of TaG6PDH and Ta6PGDH in winter wheat under cold stress. Subsequently, TaG6PDH-and Ta6PGDH were overexpressed in Arabidopsis, and showed stronger reactive oxygen species (ROS)-scavenging ability and higher survival rate compared with wild-type (WT) plants under cold stress. In addition, we found that TaG6PDH and Ta6PGDH overexpression can promote the oxidative pentose phosphate pathway (OPPP) in the cytoplasm and peroxisomes of Arabidopsis. In summary, Arabidopsis overexpressing TaG6PDH and Ta6PGDH showed improved cold tolerance.