Phytochromes are photosensory phosphoproteins with crucial roles in plant developmental responses to light.
Functional studies of individual phytochromes have revealed their distinct roles in the plant's life cycle. Given
the importance of phytochromes in key plant developmental processes, genetically manipulating phytochrome
expression offers a promising approach to crop improvement. Photo-biotechnology refers to the transgenic
expression of phytochrome transgenes or variants of such transgenes. Several studies have indicated that crop
cultivars can be improved by modulating the expression of phytochrome genes. The improved traits include
enhanced yield, improved grass quality, shade-tolerance, and stress resistance. In this review, we discuss the
transgenic expression of phytochrome A and its hyperactive mutant (Ser599Ala-PhyA) in selected crops, such
as Zoysia japonica (Japanese lawn grass), Agrostis stolonifera (creeping bentgrass), Oryza sativa (rice), Solanum
tuberosum (potato), and Ipomea batatas (sweet potato). The transgenic expression of PhyA and its mutant in
various plant species imparts biotechnologically useful traits. Here, we highlight recent advances in the field of
photo-biotechnology and review the results of studies in which phytochromes or variants of phytochromes
were transgenically expressed in various plant species.We conclude that photo-biotechnology offers an excellent
platform for developing crops with improved properties.