Overexpression of the white clover TrSAMDC1 gene enhanced salt and drought resistance in Arabidopsis thaliana. Jia Tong,Hou Jieru,Iqbal Muhammad Zafar,Zhang Youzhi,Cheng Bizhen,Feng Huahao,Li Zhou,Liu Lin,Zhou Jiqiong,Feng Guangyan,Nie Gang,Ma Xiao,Liu Wei,Peng Yan Plant physiology and biochemistry : PPB S-adenosylmethionine decarboxylase (SAMDC) mediates the biosynthesis of polyamines (PAs) and plays a positive role in plants' response to adversity stress tolerance. In this study, we isolated a SAMDC gene from white clover, which is located in mitochondria. It was strongly induced when white clover exposed to drought (15% PEG6000), salinity (200 mM NaCl), 20 μM spermidine, 100 μM abscisic acid, and 10 mM HO, especially in leaves. The INVSc1 yeast introduced with TrSAMDC1 had tolerance to drought, salt, and oxidative stress. Overexpression of TrSAMDC1 in Arabidopsis showed higher fresh weight and dry weight under drought and salt treatment and without growth inhibition under normal conditions. Leaf senescence induced by drought and saline was further delayed in transgenic plants, regardless of cultivation in 1/2 MS medium and soil. During drought and salt stress, transgenic plants exhibited a significant increase in relative water content, maximum photosynthesis efficiency (Fv/Fm), performance index on the absorption basis (PI), activities of antioxidant protective enzymes such as SOD, POD, CAT, and APX, and a significant decrease in accumulation of MDA and HO as compared to the WT. The concentrations of total PAs, putrescine, spermidine, and spermidine in transgenic lines were higher in transgenic plants than in WT under normal and drought conditions. These results suggested that TrSAMDC1 could effectively mitigate abiotic stresses without the expense of production and be a potential candidate gene for improving the drought and salt resistance of crops. 10.1016/j.plaphy.2021.05.018

The response mechanism to salt stress in Arabidopsis transgenic lines over-expressing of GmG6PD. Jin Jie,Li Keke,Qin Juan,Yan Lili,Wang Shengwang,Zhang Guohong,Wang Xiaomin,Bi Yurong Plant physiology and biochemistry : PPB Glucose-6-phosphate dehydrogenase (G6PD or G6PDH) plays an important role in response to salt stress in plants. However, much less is known about G6PD proteins in soybean (Glycine max L.). Here, we found that a soybean cytosolic G6PD gene, GmG6PD7, was induced by NaCl. We generated Arabidopsis transgenic lines overexpressing GmG6PD7. The seed germination rate and primary root length of Arabidopsis thaliana over-expressing GmG6PD7 under NaCl treatment were enhanced. Salt stress induced an obvious increase of the total and cytosolic G6PD activity and the marked decrease of ROS levels in the transgenic plants. At the same time, over-expressing GmG6PD7 in Arabidopsis affected the glutathione and NADPH level and activated ROS scavengers, suggesting that GmG6PD7 contributes to increase salinity tolerance by decreasing ROS accumulation. What's more, we found GmG6PD7 overexpression led to the up-regulation of abscisic acid (ABA) degradation gene and the down-regulation of ABA synthesis and ABA-responsive genes, which finally reduced ABA content to improve seed germination rate under salinity stress. It was noteworthy that GmG6PD7 can rescue the seed and root phenotype of Arabidopsis cytosolic G6PD mutant (Atg6pd5 and Atg6pd6) under salt stress, suggesting cytosolic G6PD may have a conserved function in soybean and Arabidopsis. 10.1016/j.plaphy.2021.02.021

AtMYB109 negatively regulates stomatal closure under osmotic stress in Arabidopsis thaliana. So Won Mi,Huque A K M Mahmudul,Shin Hyun-Young,Kim Soo Youn,Shin Jin Seok,Cui Meihua,Shin Jeong Sheop Journal of plant physiology Osmotic stress, caused by drought, salinity, or PEG (polyethylene glycol), is one of the most important abiotic factors that hinder plant growth and development. In Arabidopsis, more than 100 R2R3-MYB transcription factors (TFs) have been identified, and many of them are involved in the transcriptional regulation of a variety of biological processes related to growth and development, as well as responses to biotic and abiotic stresses. However, the MYB TF involving in both plant development and stress response has rarely been reported. We report here that Arabidopsis AtMYB109, a R2R3-MYB TF, functions as a negative regulator of stomatal closure under osmotic stress as well as of pollen tube elongation. Under PEG-induced osmotic stress, whole leaves of AtMYB109-OXs were intensely wilted, while leaves of the wild-type (WT) and myb109 were weakly affected. Moreover, we confirmed that the wilting in AtMYB109-OXs was more severe than in WT and myb109 under drought conditions, and that after re-watering, WT and myb109 plants promptly recovered, while AtMYB109-OXs failed to survive. In addition, stomatal closure was delayed in the AtMYB109-OXs compared to the WT and myb109. However, proline content and the expression of stress-induced and proline synthesis genes were higher in the overexpression lines than in WT and myb109. Then, we observed that the expression of ICS1, a key gene in SA biosynthesis, was greatly suppressed in AtMYB109-OXs. In addition, we found that AtMYB109 expression gradually increased until the flowers were fully opened and thereafter dramatically decreased during silique development. The pollen tube growth was significantly suppressed in AtMYB109-OXs compared to the WT and myb109. Using EMSA and ChIP-qPCR, we confirmed that AtMYB109 bound to the promoter of RABA4D, a gene encoding a pollen development regulator. Taken together, we suggest the delayed stomatal closing and vulnerable phenotypes in the AtMYB109-OXs under osmotic stress are possibly directly or indirectly associated with a SA-mediated mechanism, and that AtMYB109 suppresses RABA4D that modulates pollen tube growth. 10.1016/j.jplph.2020.153292