Research progress in cold tolerance mechanism of grape

Abstract:Grapevines (Vitis spp.) are deciduous vine of the genus Vitis in the Vitaceae family, with a long history of cultivation. Grapes can be eaten fresh or dried, or processed into juice or wine. They are nutritious and profitable and grown in many countries. Grapes play an important role in the fruit industry in China. In the high-quality grape producing areas in north China, late frost and winter low temperature cause freezing damage, which is the main limiting factor that restricts the sustainable development of grape industry. At present, burying grapevine in soil for cold protection and application of warming greenhouses greatly increase the cost of grape production. It is of great significance to study mechanisms of grape responses to low temperature and to breed new grape varieties with cold resistance. This paper reviews the advances of research related to grape cold resistance. First of all, the evaluation of cold resistance of grape germplasm resources is important for the breeding of new cold resistance varieties for regions with“freezing injury caused by low temperature in winter and freezing injury caused by late frost”. It was found that wild grapes in China and the United States showed strong resistance to cold injury caused by low temperatures in winter and spring. Understandings of resistance mechanism of new grape varieties derived from mountain grapes (V. amurensis) as the main material provides a theoretical basis for cold resistance breeding. In production, plant tissue structure is the basis of its resistance to external stress conditions, which is formed in the process of evolution in order to adapt to the environment. Dormant organs (roots, bud eyes and branches) are the main structures of grapes exposed to sub-zero freezing stress. Branches and roots serve as the main organs of overwintering. Grape roots are more prone to freezing injury than branches. Therefore, it is particularly important to improve the cold resistance of roots to improve the cold resistance of the whole plants. As for the problem of late frost damage caused by the“return cold”in spring, the major damaged structure of grape is leaf. Stud-ies have found a link between the structure of grape leaves and the cold resistance of the plant. Physiological changes involved cold resistance of grapes include four aspects: (1) cell electrolyte leakage and intercellular substances; (2) antioxidation enzymes including peroxidase (POD), superoxidase (SOD), catalase (CAT) and ascorbic acid peroxidase (APX); (3) lipid peroxidation (MDA) of cell membrane; (4) cold resistance regulatory substances (soluble protein, soluble sugar and free proline). Research on molecular mechanism of grape cold resistance involves (1) basic research on the damage caused by spring“return cold”in main grape production regions; (2) exploration of the key genes for resistance breeding by using wild germplasm resources. According to gene actions, genes can be divided into (1) regulatory genes, such as C- repeat binding factor (CBF) and other transcription factors, which mainly participate in grape cold response by controlling gene expression, and (2) functional genes such as antioxidant enzyme genes, which directly participate in some physiological and biochemical processes and enhance the cold resistance of grapes. Researchers have made a great breakthrough in the excavation and functional analysis of grape cold resistance genes. Some are based on homologous cloning and functional validation of key genes that respond to low temperature in model plants, and some gene families or members have been found to be associated with low temperature in grapes for the first time. So far, the researchers have not confirmed a genetic link with high cold resistance in mountain grapes, although they have only found that some genes show a faster or more abundant expression pattern in mountain grapes than in European subspecies. On the basis of this work, there will be breakthrough in understanding the high resistance of mountain grapes and use it to improve variety resistance. Finally, in view of the research work related to grape cold resistance mechanism and some existing problems, the authors proposed these problems and possible solutions, and prospected for further research. (1) Construction of genetic population, mapping of genetic map and evaluation of cold resistance, identification of QTL related to cold resistance of mountain grape, mining associated resistance genes, and development of molecular markers for assisted breeding. (2) Pay attention to the occurrence law and relationship between low temperature and drainage, and carry out research on drainage as a single character. (3) Strengthening the research on stress response of different organs is of practical significance to reveal the resistance mechanism of grapevine.