Strategic Use of Florigen in Cotton: Evidence for Synchronization of Flowering and Termination of Vegetative Growth to Enhance Growth Habit As an Annual Row Crop

Cotton (Gossypium spp.) is naturally a photoperiodic perennial plant but is cultivated in the USA as a day-neutral annual row-crop.  Compact architecture with greater boll synchronization and earlier termination of vegetative growth are long-sought-after goals for our highly-mechanized production systems.  Yet even among elite cultivars, the residual perennial traits of asynchronous fruit set and continued vegetative growth after the onset of flowering negatively impact crop management and yield.  Virus induced flowering (VIF) is an emerging technology that delivers florigen, encoded by FLOWERING LOCUS T (FT) in Arabidopsis, from a disarmed Cotton leaf crumple virus vector.  Florigen was originally described as a flowering hormone, but increasing evidence points to an expanded role in promoting general determinate growth.  In the domesticated cotton accession Delta Pine 61, VIF promotes determinate growth, yielding plants with a compact growth habit and early termination of sympodial growth, resulting in more synchronous flowering and fruiting and enhanced “annualization”.  These analyses are currently being extended to other G. hirsutum and to G. barbadense accessions.  Our findings extend our understanding of florigen as a general growth hormone that regulates shoot architecture by advancing organ-specific and age-related determinate growth.  Judicious manipulation of FT expression may prove valuable for enhancing cotton management and production.