Root growth in transgenic tobacco plants with overexpression of the PtrXTH1 gene encoding xyloglucan endotransglycosylase under abiotic stress

Xyloglucan endotransglycosylases are hydrolytic cell wall enzymes that are involved in the regulation and promotion of plant growth. Overexpression of genes encoding xyloglucan endotransglycosylases can have a positive effect on the growth and stress tolerance of transgenic plants; however, the mechanisms of such influence remain poorly understood. This study was aimed at creating transgenic tobacco plants with overexpression of the PtrXTH1 gene encoding aspen xyloglucan endotransglycosylase, as well as conducting a morphophysiological analysis of their roots under abiotic stress. The transgenic tobacco plants were characterized by an increased root length as compared to wild plants, both under optimal conditions and in response to salinity (100 mM sodium chloride), low temperature (12 degrees C), and cadmium contamination (200 mu M cadmium acetate). The area of root parenchyma cells in transgenic tobacco plants is larger as compared to wild plants only under the effect of cadmium acetate, whereas under normal conditions and under low-temperature and salinity stress, no difference in cell size was observed. The PtrXTH1 gene overexpression contributed to the increased total antioxidant capacity in the roots, as well as a higher content of proline, water-soluble sugars, and oxidized and reduced glutathione, in the context of the three stress factors. Thus, the PtrXTH1 transgene stimulates the growth of tobacco roots under normal and abiotic stress conditions, which is accompanied by positive changes in the antioxidant system.