Comparative transcriptomic analysis of cassava genotypes under extended photoperiodism across flowering stages

Abstract

Cassava (Manihot esculenta Crantz) is a major staple crop across tropical and subtropical regions. Despite advances in genomic selection, delayed, non-flowering, and asynchronous flowering remain key bottlenecks in breeding programs. To better understand the molecular basis of flowering-time variation, we performed RNA sequencing across three genotypes with contrasting flowering phenotypes (early, late, and non-flowering) sampled at three developmental stages under contrasting light regimes in field conditions (natural light and three-hour night-break with white light). Comparative transcriptomic analysis revealed distinct gene expression patterns associated with flowering responses. Genotype comparisons with no light supplementation revealed stage-specific enrichment of biological processes. Light supplementation was associated with changes in the expression of key components of photoperiodic and circadian regulation, as well as pathways involved in flowering-time integration and hormone and sugar-related signaling. These findings suggest that coordinated changes across multiple biological pathways regulate flowering behavior in cassava. The candidate genes and expression patterns reported provide a foundation for functional studies and advance our understanding of molecular mechanisms governing flowering-time regulation in cassava.