Genome-Wide Identification and Expression Analysis of the Xyloglucan Endotransglucosylase/Hydrolase Gene Family in Manihot esculenta

Background: Xyloglucan endotransglucosylase/hydrolase (XTH) acts as a key cell wall-modifying enzyme and contributes to plant stress resilience. This study aimed to identify the MeXTH gene family in cassava and characterize its potential functions in abiotic stress adaptation. Method: A full set of bioinformatic analyses was performed, including phylogeny, gene structure, conserved motifs, chromosomal localization, synteny, promoter cis-elements and subcellular localization. Expression patterns were examined by quantitative real-time PCR (qRT-PCR). Results: Forty-two MeXTH genes were identified and distributed on 14 chromosomes, encoding proteins with conserved Glyco_hydro_16 (Glycoside hydrolase family 16) and XET_C (Xyloglucan endotransglycosylase C-terminal domain) domains. Genes were clustered into four subfamilies with similar structures. Synteny was closer between cassava and dicots than monocots. Twenty-four stress-, hormone- and light-related cis-elements were detected. Ten MeXTH genes showed obvious differential expression under stress, and most proteins were located in the cell wall. Conclusions: The MeXTH gene family is structurally conserved and can serve as a readout of abiotic stress in cassava. These results provide a theoretical basis for molecular breeding aimed at enhancing stress resistance in cassava.