Carpel-specific down-regulation of GhCKXs in cotton significantly enhances seed and fiber yield

Carpel-specific enhancement of cytokinin significantly increases cotton ovule number and cotton yield without detrimental phenotypes. Cytokinin is considered to be an important driver of seed yield. To increase the yield of cotton while avoiding the negative consequences caused by constitutive overproduction of cytokinin, we down-regulated specifically the carpel genes for cytokinin oxidase/dehydrogenase (CKX), a key negative regulator of cytokinin levels, in transgenic cotton. The carpel-specific down-regulation of CKXs significantly enhanced cytokinin levels in the carpels. The elevated cytokinin promoted the expression of carpel- and ovule-development-associated genes, GhSTK2, GhAG1, and GhSHP, boosting ovule formation and thus producing more seeds in the ovary. Field experiments showed that the carpel-specific increase of cytokinin significantly increased both seed yield and fiber yield of cotton, without resulting in detrimental phenotypes. Our study details the regulatory mechanism of cytokinin signaling for seed development, and provides an effective and feasible strategy for yield improvement of seed crops.

Automated summary

By specifically down-regulating the carpel genes for cytokinin oxidase/dehydrogenase, cytokinin levels were increased, leading to enhanced ovule formation and increased yield. This study provides a feasible strategy for improving seed crop yield.