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CORESTA Congress, Kunming, 2018, Agronomy/Phytopathology Groups, APPOST 23

Overexpression of tobacco GCN2 induces plant response to various stresses

LI Ning; YANG Yongxia; ZHANG Songjie; ZHAO Qi; LONG Yue; JIA Hongfang; ZHANG Songtao
Henan Agricultural University, College of Tobacco Science, Tobacco Cultivation Key Laboratory of China Tobacco, Zhengzhou 450002, P.R. China

The study of the mechanism of GCN2 involved in the plant response to various stresses could provide a theoretical basis for crop variety breeding. General control non-derepressible-2 (GCN2) could phosphorylate the α subunit of the eukaryotic initiation factor eIF2 to down-regulate the initiation of protein synthesis, subsequently reducing the global protein biosynthesis. GCN2 could also respond to biotic and abiotic stresses. To investigate the function of GCN2 and explore its roles in plant stress response, we cloned NtGCN2 from Nicotiana tabacum by RACE-PCR. The expression of NtGCN2 and the phosphorylation of NteIF2α were then analyzed with plant hormones, including salicylic acid (SA), azelaic acid (AZA), methyl jasmonate (MeJA). Analysis of different stresses (Bemisia tabaci infection, drought, and cold) was done with Real-time quantitative RT-PCR and west-blotting, respectively. The results indicated that NtGCN2 is involved in the response of plants to multiple biotic and abiotic stresses. The content of total soluble sugars and reducing sugars decreased, whereas that of chlorophyll a and b increased in the OE plants. We also observed that the overexpression of NtGCN2-1 significantly influenced different physiological processes, promoting seed germination and root elongation. The content of total soluble sugars and reducing sugars decreased, whereas that of chlorophyll a and b increased in the GCN2 overexpressing plants. In addition, the overexpressing plants had a lower content of reactive oxygen species and exhibited higher antioxidant activities. These physiological alterations could be attributed to the changes in endogenous phytohormones, decrease in the SA and abscisic acid content, and accumulation of MeJA and AZA. It indicated that the overexpression of NtGCN2 in tobacco stimulated the plant defense responses via phosphorylation of NteIF2α and the regulation of plant hormones, and via changes in the antioxidant ability and plant nutrient status.