Changes in cell wall components and polysaccharide-degrading enzymes in relation to differences in texture during sweetpotato storage root growth

Abstract

Sweetpotato has special texture characteristics, which directly affect the eating quality and post-production processing quality of sweetpotato. To investigate the texture change mechanism of sweetpotato during the growth process, this study selected two varieties with significant differences in texture from 35 varieties. The storage roots were sampled at 50, 80, 110, and 140 days after planting. Measure the texture parameters, the cell wall composition content, cell wall-related enzyme activities and the expression of expansin genes of sweetpotato storage roots. The results show that the hardness, adhesiveness and chewiness parameters of ‘Yushu No 10′ were significantly lower than those of ‘Mianfen No 1′, they have significantly different texture properties. In terms of cell wall composition, the soluble pectin content of ‘Yushu No 10′ was more than twice that of ‘Mianfen No 1′, whereas the insoluble pectin content was lower than that of ‘Mianfen No 1′, with the cellulose content of ‘Yushu No 10′ being significantly higher than that of ‘Mianfen No 1′. In terms of cell wall-related enzymes, ‘Yushu No 10′ hardness gumminess and chewiness had a significant correlation with hemicellulose activity, and ‘Mianfen No 1′ had insignificant correlation with four cell wall-related enzymes. Expansin genes were also expressed differently during the various stages of root tubers expansin. The expressions of IbEXP1, IbEXP2 and IbEXPL1 were significantly correlated with the changes in cell wall component content, and were related to the qualitative structure changes. The research conclusion shows that the texture changes during the growth of sweetpotato are related to cell wall composition, cell wall-related enzyme activity changes, and the expression of expansin genes. This study provides theoretical guidance for in-depth study of texture changes of sweetpotato, post-harvest processing and utilization and quality improvement of storage roots.