Differential Global Genomic Changes In Response To Different Drought Stress In Two Rice Cultivars Root

Drought stress is one of the most severe abiotic stresses that can injure plant life and development. Worldwide, one-third of the total land area is continually stressed by drought, thereby causing substantial crop losses in agricultural production. In order to improve plant resistance to drought, agricultural scientists have been working on transgenic technology and traditional breeding methods in response to this challenge.We used the Affymetrix rice genome array to study the gene expression change in response to low (T1 treatment), middle (T2 treatment), and high osmotic stresses (T3 treatment) in rice root of two different cultivars at the transcription level. Our experiment results as followed:1. The (X|-)_x-119/(X|-)_a-5 indices of maximum root length, total root length, root volume, and lateral root length observed between X-119 and A-5 under T1, T2, and T3 treatment were examined, results showed that there were significant differences of maximum root length, total root length, root volume, and lateral root length between X-119 and A-5 for 1-6day under all drought treatments. The differences of root system between two genotypes suggested that root system of X-119 possessed stronger lateral roots, the growing capacity into soil greatly, the larger volume, and the longer roots than that of A-5 to absorb water and nutrient to adapt to drought environment. Moreover the advantages of maximum root length of X-119 under T2 treatment, root volume under T1 treatment, lateral root length and maximum root length under T3 treatment were the most obvious among all drought treatments (Fig.1).2. Root characteristic of two cultivars were inhibited growth under T3 treatment and the tendency of Aihua5 was more obvious than that of Xiangfengzao119. T1 and T2 treatment could promote root characteristic of Xiangfengzao119, but promote or not those of Aihua5.3. Maximum root length, total root length, root volume, and lateral root length could be drought selection indexes and root quantity should be drought sensitive index.4. The effects of drought treatments on physiological changes were significant between Xingfengzao119 and Aihua5. SOD activity, POD activity and root activity could be drought selection indexes and MDA and Pro content should be drought sensitive index.5. A total of 1706 genes and 2082 genes in response to each one drought at Xingfengzao119 and Aihua5 respectively, 3953 genes of two cultivars were induced under each T1, T2 and T3 treatment and the number of overlap of two cultivars was 38 under all drought treatments. 6. The down-regulated genes of Aihua5 under T1 treatment at transcription level were genes on transport, transcriptional regulation, carbohydrate metabolism and chitin metabolism and the up-regulated genes were on biological synthesis, metabolism, water response, transport and transcriptional regulation. The down-regulated genes of Aihua5 under T3 treatment at transcription level were on cell apoptosis, carbohydrate metabolism, cell wall metabolism, transport and transcriptional regulation and the up-regulated genes were on biological synthesis, metabolism, photosynthesis, water and oxidation response and so on.7. The down-regulated genes of Xiangfengzao119 under T1 treatment at transcription level were genes on biological synthesis, carbohydrate metabolism, cell wall metabolism, transport and transcriptional regulation, and so on, and the up-regulated genes were on carbohydrate metabolism, Zn, Na, lipids and sucrose transport. The down-regulated genes of Xiangfengzao119 under T3 treatment at transcription level were on carbohydrate metabolism, cell wall metabolism and fatty acid biological synthesis, and so on, and the up-regulated genes were on biological synthesis, water response, transport, transcriptional regulation and protein folding and modification.8. The differences of response ways to drought between Xingfengzao119 and Aihua5 under T1 treatment were that oxygen and the genes activities of electron transport, xylan, malic acid and chitin metabolism, protein folding, antibiotics biological synthesis and transcriptional regulation were lower that those of Aihua5. And the activities of genes encoding endogenous response and starch metabolism were higher than those of Aihua5. The differences of response ways to drought between Xingfengzao119 and Aihua5 under T1 treatment were similar to T1 treatment, but the activities of gene encoding a histone deacetylase and arginine, polyamines biological synthesis were significantly lower than those of Aihua5 and the activities of gene encoding jasmonate acid and ABA biological synthesis were significantly higher than those of Aihua5. The differences of response ways to drought between Xingfengzao119 and Aihua5 under T3 treatment were that the activities of gene encoding GTP regulation, transcriptional regulation, electron transport and photorespiration were significantly lower than those of Aihua5 and the activities of gene encoding carbohydrate metabolism, protein folding and transport, and so on, were significantly higher than those of Aihua5.9. By using Realtime PCR to study 13 genes expression variation, the results show six types and each type of expression is day fluctuation.