CsCMV-mediated transient delivery of Arabidopsis FT enables virus-induced flowering in cassava

Cassava ( Manihot esculenta Crantz) exhibits highly variable and often delayed flowering, which limits controlled hybridization and breeding efficiency. Virus-induced flowering (VIF) provides a transient approach for manipulating flowering time, but this strategy has not yet been established in cassava. Here, we investigated whether transient delivery of Arabidopsis thaliana FLOWERING LOCUS T ( AtFT ) through a Cassava common mosaic virus (CsCMV)-based vector could promote flowering and reproductive development in cassava. A recombinant CsCMV2-AtFT vector was introduced into three cassava cultivars (TMS 60444, HN and SM 1219-9) by agroinoculation. Flowering occurred in 73.3–76.7% of CsCMV2-AtFT-inoculated plants across the three cultivars, whereas none of the CsCMV2-NC control plants flowered under identical growth conditions. The first visible floral buds appeared at 21.8–29.1 days post inoculation, and anthesis occurred at 43.3–62.0 days depending on cultivar. RT-PCR and western blot analysis confirmed systemic AtFT transcript and protein expression in CsCMV2-AtFT-inoculated plants. Virus-induced flowers exhibited normal female and male floral morphology. In HN plants, CsCMV2-AtFT treatment was associated with significantly higher transcript levels of endogenous flowering-associated genes, including MeSOC1-1/2 , MeFUL , MeLFY1/2 and MeAP1-1/2/3 . Furthermore, induced flowers were reproductively functional, as demonstrated by geitonogamous hand pollination and production of mature fruits containing seeds. These findings demonstrate that CsCMV-mediated transient AtFT delivery promotes flowering and reproductive development in cassava without stable transformation or tissue culture. This study expands the application of CsCMV-based biotechnology toward transient regulation of reproductive traits and provides a potential approach for controlled flowering and pollination in cassava.