The Influence Of Water Stress On Rice Blast Resistance Mechanisms And The Disease Index

Rice is one of the main food crops in the world, and the rice blast and drought are the main biological stresses and abiotic stress factors affecting the rice production, and thus to understand and master the mechanism of water stress on rice resistance to rice blast and the impact of disease severity and use it to reduce the incidence of disease and loss have important theoretical and practical significance. This study uses artificial way to control the moisture and to use PEG6000 to simulate water stress, inoculate rice blast fungus after handling Kongyu 131 and Longjing 31 with different degree water stress, by testing the change of enzyme activity in leaves after inoculation, analyzing the differences of the expression of resistance genes, investigating incidence and measuring its output after harvest, to clear the influence of water stress on rice resistant mechanism and disease severity, and it can provide theoretical guidance on taking reasonable field drying harm to prevent and control the occurrence of rice blast. The results show that:1. Inoculating the rice blast fungus under the condition of water stress in rice seedling stage and tillering stage, the results showed that the low intensity water stress is conducive to enhance enzyme activity and to the accumulation of related material, but the intensity of higher water stress on the contrary, and in the pot experiment with-30 kpa water stress treatment and hydroponic experiment with 5% PEG6000, the activity of varieties of related enzyme is highest and the quantity of resistance related materials is biggest.2. In rice seedling stage and tillering stage to take appropriate low intensity of water stress can reduce the incidence rate of the rice blast, and high intensity of water stress can aggravate the occurrence of diseases. Under different water stress, the rice disease resistance is related to the activity of antioxidant enzyme and the content of resistant materials.3. Kongyu 131 is most productive when the water stress treatment is at-15 kpa, 16.28% higher than the CK, while Longjing 31 has the highest yield when the water stress is at-30 kpa, 15.73%higher than the CK. This indicates properly low intensity water stress in tillering stage of rice has a tendency to increase production. Water stress treatment and the infection of rice blast fungus have a significant impact on the effective number of panicles, the number of grain per spike, the seed setting rate, but have no significant effect for the weight of thousand grains of rice.4. Adopt the method of semi-quantitative RT-PCR to detect the differences of the numbers of resistance-related gene expression, the results showed that the expressive quantities of OsPAL and OsPR3-1 of Longjing 31 with the same stress treatment are higher than Kongyu 131, and the expressive amounts of the CATB and Mn-SOD of Kongyu 131 are higher than Longjing 31, and the expressive amount is relatively low. This reflects that different varieties internal regulatory mechanisms in the face of various adversity stresses are different. Overall, low-intensity water stress can promote the expression of this 4 genes, and the higher intensity water stress will inhibit its expression.