Plant Growth and Development Under Suboptimal Light Conditions

Light regulates various processes throughout the plant life from seed germination to flowering. Photoreceptors (phytochromes and cryptochromes) sense the changes in light conditions that trigger various signaling mechanisms resulting in upregulation and downregulation of several genes and transcription factors. Therefore, genetic and physiological responses, i.e., seedling growth and development, skotomorphogenesis, photomorphogenesis, shade avoidance, and flowering, are regulated by the changes in gene expression mediated by light. Phytohormones are also involved in controlling these developmental changes. Light also plays an important role in plant defense against various pathogens by inducing the jasmonic acid and salicylic acid pathways that trigger SAR (systemic acquired response). Once the plant becomes reproductively competent, light regulates the complex process of floral initiation by activation of floral genes and flowering hormones.