Research progress on the response and adaptation mechanism of rice to low-light stress

Rice is one of the most important food crops in China, and light has an important effect on its yield and quality. With the deterioration of the global climate, the low light stress brought by the frequent rainy weather has become an important limiting factor affecting the high and stable yield and high quality production of rice. The safe, stable and sustainable production of rice is of great significance to ensure food security and meet people's demand for food. Therefore, this paper summarized the research results in recent years, and reviewed the effects of low light stress on rice morphological characteristics such as roots, stems, leaves and flower organs, physiological characteristics such as photosynthetic characteristics, pollen fertilization, assimilate transport and enzyme activities related to starch synthesis, biochemical characteristics such as nitrogen metabolism, hormone regulation, photoreceptor regulation, antioxidant system and osmotic regulation. The molecular response mechanism of rice under low light stress was emphasized, and the future research direction and hotspot of rice shade tolerance were prospected. In terms of morphological characteristics, shade-tolerant rice varieties could maintain higher root absorption area and α-naphthalamine oxidation capacity under low light stress, increase the content of non-structural carbohydrates and structural carbohydrates in stems, increase stomatal density and photosynthetic membrane area in leaf, and reduce stomata, so as to improve photosynthesis. In terms of physiological and biochemical characteristics, the shade avoidance response is regulated by photoreceptors, the content of osmoregulatory substances is increased, and the antioxidant system is activated to remove reactive oxygen species. In terms of molecular response, low light stress can be responded to through the expression of shade tolerance genes, light signaling pathway genes and hormone pathway related genes, and the regulation of transcription factors. At present, most studies on shade tolerance of rice focus on the effects of low light stress on growth, yield and quality of rice, but its molecular response mechanism has not been clarified in detail. In this paper, it is pointed out that the adaptation mechanism of rice to low light stress at the genetic level and related shade tolerance genes should be further studied in the future. Studying its molecular regulation mechanism and combining genetic engineering with crop genetics and breeding technology will help us to dig out shade-tolerant genes in rice, select shade-tolerant rice varieties, and further improve cultivation techniques, so as to play a guiding role in actual production. It provides theoretical basis and practical basis for high yield, stable yield and high quality cultivation of rice.