Dr. Yongchao Liang “Silicon and Abiotic Stress in Plants" скачать в хорошем качестве

Dr. Yongchao Liang “Silicon and Abiotic Stress in Plants"

“Silicon and Abiotic Stress in Plants: Current Knowledge and Future Research Needs" Dr. Yongchao Liang Professor Chinese Academy of Agricultural Science Silicon (Si) is the second most abundant element in soils. Although Si has not yet been listed among the essential elements for higher plants, its beneficial roles in improving the growth and development of plants, particularly under stressful environments, have been well documented. More recently, rapid progress has been made in cloning and functional analysis of genes responsible for silicon uptake, transport and distribution in plants. Silicon is well-known to effectively mitigate various forms of abiotic stress such as salinity, drought, freezing, high temperature and UV radiation stresses and metal toxicities including aluminum, iron, manganese, cadmium, arsenic and zinc toxicity etc. However, the mechanisms underlying remain poorly understood. In this paper, we reviewed the updated knowledge of the roles of silicon-enhanced resistance to abiotic stresses in plants. There are a number of external and internal strategies by which plants are adapted or tolerant to abiotic stresses. For examples, Si-enhanced metal tolerance can be attributed to 1) external mechanisms including reduced metal ion activity because of silicate-caused pH rise and Si co-deposition with metals in growth media, and 2) in plant mechanisms including metals and Si co-deposition within plants, inhibited root-to-shoot metal transport, more metals bound to root cell walls and Si-mediated antioxidant defense capacity. For salinity tolerance, Si-mediated osmotic stress and ionic rebalance with enhanced K but reduced Na uptake and transport, and reduced membrane lipid peroxidation and improved membrane structure and stability caused by enhanced antioxidant defense activities contribute mainly to Si-enhanced salinity tolerance. However, we think that Si-enhanced antioxidant defense capacity is the universal and major strategy for Si-mediated tolerance to such abiotic stress as salinity, freezing, drought and heavy metals stress in plants. Finally we discussed future research needs for Si-mediated alleviation of abiotic stresses, and for Si-improved eco-environmental quality and health. Silicon has not been given the same level of attention as a limiting factor in soil fertility and crop production as other nutrients. This view is changing as agronomists become more aware of the valuable function of silicon nutrition in crops and soils and even animal life. Research conducted on many soils worldwide has shown that supplying crops with plant available silicon can suppress disease, reduce insect attack, improve environmental stress tolerance and increase crop productivity. Silicon is now officially designated as a plant beneficial substance by the Association of American Plant Food Control Officials (AAPFCO). Plant available silicon may now be listed on fertilizer labels. Soil scientists and agronomists from the United States, Canada, China and Brazil took part in the symposium formally called Silicon Soil Fertility and Nutrient Management. It was held in October, 2012 in Cincinnati, Ohio at the Tri-Societies Conference conducted by the American Society of Agronomy (ASA), the Crop Science Society of America (CSSA) and the Soil Science Society of America (SSSA).