Molecular insight into the photoperiod sensitivity in crop plants

The reproductive phase of the plant is critically regulated by various internal and external factors. Among these, photoperiod sensitivity is one of the key factors that counts the day length to sense the upcoming favourable environmental conditions for flowering and post-flowering events. Photoperiod-sensitive plants have an internal photoperiod-sensing mechanism regulated through a cascade of genes. Induction of flowering in plants largely depends upon the expression of the Flowering Locus T (FT), which encodes florigen, a systemic signalling molecule required to trigger flower induction. It is synthesized in leaves and translocated to the shoot meristem through the phloem. Photoperiod sensitivity in crop plants is a big constraint for production. Strong photoperiod requirements of crop plants for flowering restrict their cultivation to specific geographical niches in a single season. Identifying the gene(s)/QTL(s) for photoperiod sensitivity and the development of day-neutral genotypes is a prime area of research. The availability of day-neutral genotypes in crop plants promises wider adaptability under diverse agroecological environments with multi-seasonal cropping in a year. This review takes into account the genes and QTLs discovered in major cereal and pulse crops and elucidates various mechanisms behind their photoperiod responses. Furthermore, it emphasizes the use of genome editing for photoperiod engineering and explores the prospect of using various modern, cutting-edge technologies for photoperiod research in crop plants.