Identification of the Xyloglucan Endotransglycosylase/Hydrolase (XTH) Gene Family Members Expressed in Boehmeria nivea in Response to Cadmium Stress

Abstract

Xyloglucan endotransglycosylase/hydrolase (XTH) genes play an important role in plant resistance to abiotic stress. However, systematic studies of the response of Boehmeria nivea (ramie) XTH genes (BnXTHs) to cadmium (Cd) stress are lacking. We sought to identify the BnXTH-family genes in ramie through bioinformatics analyses and to investigate their responses to Cd stress. We identified 19 members of the BnXTH gene family from the ramie genome, referred to as BnXTH1-19, among which BnXTH18 and BnXTH19 were located on no chromosomes and the remaining genes were unevenly distributed across 11 chromosomes. The 19 members were divided into four groups, Groups I/II/IIIA/IIIB, according to their phylogenetic relationships, and these groups were supported by analyses of intron–exon structure and conserved motif composition. A highly conserved catalytic site (HDEIDFEFLG) was observed in all BnXTH proteins. Additionally, three gene pairs (BnXTH6–BnXTH16, BnXTH8–BnXTH9, and BnXTH17–BnXTH18) were obtained with a fragment and tandem-repeat event analysis of the ramie genome. An analysis of cisregulatory elements revealed that BnXTH expression might be regulated by multiple hormones and abiotic and biotic stress responses. In particular, 17 cisregulatory elements related to abiotic and biotic stress responses and 11 cisregulatory elements related to hormone responses were identified. We also found that most BnXTH genes responded to Cd stress, and BnXTH1, BnXTH3, BnXTH6, and BnXTH15 were most likely to contribute to the Cd tolerance of ramie, as evidenced by the substantial increases in expression under Cd treatment. Heterologous expression of BnXTH1, BnXTH6, and BnXTH15 significantly enhanced the Cd tolerance of transgenic yeast cells. These results suggest that the BnXTH gene family is involved in Cd stress responses, laying a theoretical foundation for functional studies of BnXTH genes and the innovative breeding of Cd-tolerant ramie.

Analysis of Codon Usage Bias in Xyloglucan Endotransglycosylase (XET) Genes

“…Xyloglucan endotransglucosylase/hydrolase (XTH) is a key xyloglucan modifying enzyme belonging to the glycoside hydrolase 16 (GH16) family, which catalyzes the cleavage and polymerization of xyloglucan molecules to modify the celluline–xyloglucan complex structure of seed germination [ 17 , 18 ], and cell walls [ 19 ] and elongation [ 20 , 21 ]. XTHs, which are directly involved in the initial assembly and subsequent restructuring of primary cell walls [ 22 , 23 ], exhibit two diverse catalytic activities: xyloglucan endohydrolase (XEH) and xyloglucan endotransglycosylase (XET) [ 24 ].…”

“…XET is one of the most important parts of ancient machinery regulating cell wall modifications [ 32 ]. In different species, the XET gene is involved in seed germination [ 18 ], cell wall construction [ 33 ], and abiotic stress response [ 21 , 26 ], indicating that the function of the XET gene is significantly different.…”

Genome-Wide Analysis of the Xyloglucan Endotransglucosylase/Hydrolase (XTH) Gene Family: Expression Pattern during Magnesium Stress Treatment in the Mulberry Plant (Morus alba L.) Leaves

“…For example, in response to cadmium (Cd) stress, the expression of BnXTH1 , BnXTH3 , BnXTH6 , and BnXTH15 was observed to be upregulated in Boehmeria nivea . Conversely, BnXTH18 , BnXTH16 , BnXTH17 , and BnXTH5 exhibited notable downregulation under the same Cd stress conditions [ 62 ].…”

Genome‐wide identification of XTH gene family in Musa acuminata and response analyses of MaXTHs and xyloglucan to low temperature

“…In the present study, 53 MaXTHs have been identified in Genome A of banana, which were divided into 3 subclasses: Group I/II, Group IIIA and Group IIIB as other plants. Plant XTHs have been identified in many plants and the family member varies from 19 (Ma et al, 2022) to 61 (Song et al, 2018).…”

“…To date, the XTH family has been identified in many plants. For example, there are 33 XTHs in Arabidopsis (Yokoyama and Nishitani, 2001), 56 in Nicotiana tabacum (Wang et al, 2018), 61 in Glycine max (Song et al, 2018), 34 in Citrus sinensis (Li et al, 2019a), 48 in Ananas comosus (Li et al, 2019b), 36 in Ipomoea batatas (Zhang et al, 2023), 19 in Boehmeria nivea (Ma et al, 2022), 14 in Camellia sinensis (Wu et al, 2021), respectively.…”