Some introns can act as cis -elements to enhance gene expression without altering promoter specificity. Here, we engineered the castor bean catalase 1 first intron ( CatI ) by mutagenesis and identified CatI-mu7 , which exhibited enhanced fusion-gene expression and improved splicing accuracy in Nicotiana benthamiana, Arabidopsis , Solanum lycopersicum , and rice. Knock-in of CatI-mu7 into HSP101 increased male fertility under heat stress in rice and Arabidopsis compared with wild-type and CatI knock-in controls, highlighting its potential applications in crop breeding.
Qiu et al. (2026) studied this question.