Sterol glycosyltransferases required for adaptation of Withania somnifera at high temperature

Abstract

Heat is a major environmental stress factor that confines growth, productivity, and metabolism of plants. Plants respond to such unfavorable conditions through changes in their physiological, biochemical and developmental processes. Withania somnifera, an important medicinal plant, grows in hot and dry conditions, however, molecular mechanisms related to such adaptive properties are not known. Here, we elucidated that members of the sterol glycosyltransferases (SGT) gene family play important roles in the survival of W. somnifera under adverse conditions through maintaining the integrity of the membrane. SGTs are enzymes involved in sterol modifications and participate in metabolic flexibility during stress. Silencing of WsSGT members, for instance WsSGTL1, WsSGTL2 and WsSGTL4, was inimical for important physiological parameters, such as electron transport rate, photochemical quantum yield, acceptor side limitation, non-photochemical quenching (NPQ), Fv/Fm and net photosynthetic rate, whereas stomatal conductance, transpiration rate and dark respiration rates (Rds) were increased. Decreased NPQ and increased Rds helped to generate significant amount of ROS in the Wsamisgt lines. After heat stress, H O , lipid peroxidation and nitric oxide production increased in the Wsamisgt lines due to high ROS generation. The expression of HSPs in Wsamisgt lines might be involved in regulation of physiological processes during stress. We have also observed increased proline accumulation which might be involved in restricting water loss in the Wsamisgt lines. Taken together, our observations revealed that SGTL enzyme activity is required to maintain the internal damages of the cell against high temperature by maintaining the sterol vs sterol glycosides ratio in the membranes of W. somnifera.

Leaf Lipid Alterations in Response to Heat Stress of Arabidopsis thaliana

“…Comparison of lipid composition of a heat-tolerant sorghum cultivar and a heat-susceptible sorghum cultivar identified differences in levels of SGs and ASGs under heat stress, with the heat-tolerant cultivar displaying higher levels of sterol derivatives, consistent with the notion that SGs and ASGs might play a role in improving plant response to heat [ 8 ]. Singh et al [ 47 ] showed that silencing of the genes for three glycosyltransferases that form sterol glycosides in the medicinal plant, Withania somnifera , reduced the photosynthetic rate and increased the transpiration rate of the plants under heat stress. Furthermore, ugt80B1 mutants of Arabidopsis, in which SG content is reduced by 65–80%, exhibited decreased survival of seedlings grown on nutrient agar medium for 5 days at 42 °C [ 9 ].…”

“…Our group tried repeatedly to test the hypothesis that SGs and ASGs play a role in growth or survival of Arabidopsis under heat stress. In our experimental design, 30-day-old double mutants of UGT80A2 and UGT80B1 [ 47 ] and wild-type plants were subjected to severe heat stress, 45 °C for 12 h, or a control treatment (21 °C). This 45 °C treatment was three times longer than for Path 3 in the experiment described in Figure 1 .…”

Beneficial Effect of Proline Supplementation on Goat Spermatozoa Quality during Cryopreservation

“…The key feature of proline by which it quenches singlet oxygen in somatic cells is the secondary amine structure of pyrrolidine [ 54 ]. In our previous study, we showed that the exposure of boar sperm to DL-pipecolinic acid shared secondary amine with proline improved sperm progressive motility; however, the THFA failed to do so, because lacks a secondary amine.…”

Inactivation of UDP-Glucose Sterol Glucosyltransferases Enhances Arabidopsis Resistance to Botrytis cinerea

“…Changes in the profile of glycosylated sterols have been widely related with the plant response to different abiotic stresses (Palta et al, 1993; Mishra et al, 2013; Pandey et al, 2014; Mishra et al, 2015; Saema et al, 2016; Takahashi et al, 2016; Singh et al, 2017). However, there are less experimental evidence supporting their involvement in biotic stress responses (Pandey et al, 2014; Singh et al, 2016; Mishra et al, 2017).…”

“…Forward- and reverse-genetic approaches have also shown that changes in SGT expression levels are associated to altered responses of different plant species to abiotic stress conditions. An increased sensitivity to heat and cold stress has been reported in Arabidopsis and W. somnifera plants with reduced levels of SGT (Mishra et al, 2015; Singh et al, 2017), whereas enhanced tolerance to heat, cold, and salt stress has been associated to overexpression of SGT in Arabidopsis , tobacco, and W. somnifera , respectively (Mishra et al, 2013; Pandey et al, 2014; Saema et al, 2016). These observations are consistent with the induction of SGT genes in response to abiotic stress reported in tomato (Ramírez-Estrada et al, 2017), W. somnifera (Chaturvedi et al, 2012), and cotton (Li et al, 2014), and also with changes observed in the relative proportions of glycosylated sterols in the plasma membrane of oat, rye, and potato in association with cold acclimation and freezing tolerance (Palta et al, 1993; Takahashi et al, 2016), during tomato and apple fruit chilling and after tomato fruit rewarming (Whitaker, 1991; Whitaker, 1994; Rudell et al, 2011), in wheat leaves under high day and night temperature (Narayanan et al, 2016), and in Arabidopsis under drought stress conditions (Tarazona et al, 2015).…”