The brassinosteroid‐responsive xyloglucan endotransglucosylase/hydrolase 19 (XTH19) and XTH23 genes are involved in lateral root development under salt stress in Arabidopsis

Abstract

Lateral roots (LRs) are the main component of the root system architecture in Arabidopsis. The plasticity of LR development has an important role in improving plant survival in response to the external environment. Previous studies have revealed a number of genetic pathways that control plant growth in response to environmental stimuli. Here, we find that the xyloglucan endotransglucosylase 19 (XTH19) and XTH23 genes are involved in LR development under salt stress. The density of LRs was decreased in the xth23 single mutant, which was also more sensitive to salt than the wild type, and the xth19xth23 double mutant exhibited additive downregulated LR initiation and salt sensitivity compared with the single mutant. On the contrary, constitutive overexpression of XTH19 or XTH23 caused increased LR densities. Furthermore, XTH19 and XTH23 were induced by salt via the key brassinosteroid signaling pathway transcription factor BES1. In addition, we found that 35S:: BES1 increased salt tolerance and the phenotype of xth19xth23 & 35S::BES1 was partially complementary to the wild-type level. In vivo and in vitro assays demonstrated that BES1 acts directly upstream of XTH19 and XTH23 to control their expression. Overall, our results revealed that XTH19 and XTH23 are involved in LR development via the BES1-dependent pathway, and contribute to LR adaptation to salt.

Maintenance of Cell Wall Integrity under High Salinity

“…However, the positive roles of XTHs in salt tolerance have also been reported. Constitutive expression of CaXTH3 in hot pepper [40,41] and PeXTH in Populus euphratica [42] enhance tolerance to salt stress, and disruption of XTH19 and XHT23 genes in Arabidopsis results in decreased salt tolerance [43].…”

“…Expression profiling revealed that, upon ABA or salt stress treatment, the expression of expansins, such as OsEXPA4, OsEXPA8, OsEXPB2, OsEXPB3, and OsEXPB6, and the expression of cell wall biosynthesis genes, such as endoglucanase genes OsGLU5 and OsGLU14, are negatively regulated by OsMPS [164]. XTH19 and XTH23, belonging to xyloglucan endotransglucosylase/hydrolase group II, are up-regulated by salt stress and BR [43]. In the xth23 single or xth19 xth23 double mutant, lateral root growth is disrupted under salt stress, whereas overexpression of XTH19 or XTH23 enhances salt tolerance and increases lateral root initiation [43].…”

“…XTH19 and XTH23, belonging to xyloglucan endotransglucosylase/hydrolase group II, are up-regulated by salt stress and BR [43]. In the xth23 single or xth19 xth23 double mutant, lateral root growth is disrupted under salt stress, whereas overexpression of XTH19 or XTH23 enhances salt tolerance and increases lateral root initiation [43]. BRI1-EMS-SUPPRESSOR 1 (BES1) is a transcription factor that is involved in BR signaling pathway.…”

“…BRI1-EMS-SUPPRESSOR 1 (BES1) is a transcription factor that is involved in BR signaling pathway. BES1 directly binds the promoter of XTH19 and XTH23 and positively regulates their expression under salt stress [43] (Table 1).…”

Genome-wide Identification and Expression Analysis of the Eyloglucan Endotransglucosylase/hydrolase Gene Family in Poplar

“…There has been evidence to prove it. For example, Arabidopsis XTH19 and XTH23 (a homologous gene of PtrXTH19) were regulated by BES1 to participate in the development of lateral roots through brassinosteroid signaling pathway, contributing to lateral roots adaptation to salt (Xu et al 2020). The de ciency of XTH9 (a homologous gene of PtrXTH40) in Arabidopsis regulated the secondary wall thickening by triggering integrity signal of cell wall, and stimulating the production of xylem cells (Kushwah et al 2020).…”