Relevance of Class I α-Mannosidases to Cassava Postharvest Physiological Deterioration.

Class I α-mannosidases (MNSs) play important roles in protein N-glycosylation. However, no data are currently available about MNSs in cassava (Manihot esculenta), of which the functions are therefore not known, particularly in relevance to postharvest physiological deterioration (PPD). A total of seven genes were identified from the cassava genome in the present study. Two (MeMNS2 and MeMNS6) of the seven genes may be pseudogenes, as indicated by sequence alignment and exon-intron organizations. Five MNSs could be classified into three subfamilies. Tissue-specific expression analysis revealed that MNS genes have distinct expression patterns in different tissues between sugar cassava and cultivated cassava varieties, indicating their functional diversity. A PPD response and defense model was proposed based on the transcription data of MNSs and genes involved in reactive oxygen species, signal transduction, and cell wall remodeling. The findings help in the understanding of PPD responses in cassava.