Genetic engineering of phytochrome B and PIFs: Unlocking crop productivity and stress resilience

• Phytochrome B-mediated light and temperature signaling regulates plant growth, development, and adaptation to environmental stresses, such drought, extremes temperature and shade. • Molecular interventions in PHYB and PIF-encoding genes, such as CRISPR/Cas9 editing, RNA interference, gene overexpression and genomic complementation, can be strategically employed to enhance crop resilience to abiotic stresses. • Loss-of-function mutations or downregulation of PHYB , as well as overexpression of PIF genes, play a pivotal role in enhancing drought and salinity tolerance by promoting ABA biosynthesis, and activating downstream components involved in osmoprotectant accumulation, ROS scavenging, and stress resilience, without incurring significant plant growth penalties • Mutations that stabilize the active form of PHYB under high temperatures, or enhance the activity of PIF4 and PIF7, contribute to improved thermotolerance by maintaining the expression of heat-shock proteins and other stress-responsive genes. • Manipulating PHY and PIF signaling pathways can suppress shade avoidance syndrome traits, improving canopy architecture and light distribution. Changes in environmental conditions threaten global crop yields by intensifying stresses, such as drought, salinity and extreme temperatures, which disrupt critical aspects of plant metabolism and structure. To adapt to these adverse conditions, plants have evolved various mechanisms, including the integration of light and temperature signals through phytochrome (PHY) perception. These photoreceptors play a central role in orchestrating stress responses by regulating transcriptional networks, ultimately impacting plant growth and metabolism. Recent advances in genetic engineering have opened opportunities to modulate PHYTOCHROME B (PHYB), and their downstream component expression and activities PHYTOCHROME INTERACTING FACTORS (PIFs), enabling the development of stress-resilient crop varieties. Various biotechnological techniques, such as genome editing, targeted mutagenesis, RNAi-mediated silencing, and tissue-specific overexpression, allow precise manipulation of PHYB-mediated signalling pathways. These interventions enhance crop performance under challenging conditions, including osmotic stress, extreme temperatures and light competition in densely planted systems. Furthermore, the combination of genetic engineering approaches offers a promising strategy to increase agricultural productivity in the face of global climate challenges. This review highlights the synergy between biotechnological advancements and the critical role of PHYB in advancing food security and promoting sustainable agriculture.