Cold stress at the booting stage in rice: impacts on anther development, hormonal regulation, and genetic mechanisms of tolerance

Cold stress during the booting stage severely affects rice productivity by damaging reproductive organs, particularly disrupting tapetum function and pollen development, reducing seed-setting rates, and causing substantial yield losses. Key physiological and biochemical processes, including carbohydrate metabolism, reactive oxygen species (ROS) homeostasis, and hormone-mediated signaling pathways involving abscisic acid (ABA), gibberellins (GA), auxin (IAA), cytokinins (CKs), jasmonic acid (JA), and ethylene (ET), play critical roles in regulating reproductive-stage cold tolerance. This review systematically examines the effects of cold stress on anther development, with particular emphasis on tapetum–microspore interactions and the coordinated regulation of metabolic, redox, and hormonal pathways that determine pollen fertility under low-temperature conditions. We further summarize the genetic architecture underlying cold tolerance, including major quantitative trait loci (QTLs), cloned genes, and regulatory factors such as CTB4a, CTB2, CTF1, and qCTB7, which contribute to reproductive-stage cold tolerance through diverse molecular mechanisms. Moreover, we discuss genes conferring cross-stage tolerance and evaluate their potential applications in rice breeding programs. Finally, we highlight current knowledge gaps and future opportunities for integrating genetic, physiological, and multi-omics approaches to improve reproductive-stage cold tolerance. By synthesizing these advances, this review provides a theoretical framework for developing climate-resilient rice cultivars with stable fertility and productivity under low-temperature stress.