CRISPR/Cas9 mediated knockout of MeSSI enhances resistant starch content without compromising yield in cassava

Xiaohua Lu, Yajie Wang, Yannian Che, Yuheng Li , Baochang Nong, Yujian Ge, Xiangwen Wang, Yuxuan Guo, Ruimei Li, Jiao Liu, Jianchun Guo, Yuan Yao, Mengting Geng

Carbohydr Polym.; 2026 Aug 1:385:125382. doi: 10.1016/j.carbpol.2026.125382.

Abstract

Enhancing resistant starch (RS) content in cassava is vital for developing nutritionally improved, functional food crops. In this study, targeted mutagenesis of the MeSSI gene via CRISPR/Cas9 was conducted to investigate its role in starch biosynthesis and RS accumulation. MeSSI knockout lines exhibited a 6.74-fold increase in RS content and a 16.42% elevation in amylose levels compared to the wild-type, without compromising total starch content or root yield. Starch structural analysis revealed an increased number of smaller granules per amyloplast and a shift in amylopectin chain-length distribution, characterized by reduced short chains (DP 6-12) and enrichment of intermediate and long chains, resulting in a lower branching degree. These modifications were associated with enhanced thermal stability and altered pasting behavior. Transcriptomic profiling indicated compensatory upregulation of AGPase subunits, and glycolytic genes, suggesting a reprogramming of carbon metabolism to sustain starch accumulation. This work identifies MeSSI as a key determinant of amylopectin fine structure and RS formation, providing a precise genome-editing strategy to improve the nutritional profile of cassava.

See https://pubmed.ncbi.nlm.nih.gov/42173587/

Graphical abstract