Effects Of Drought Stress On Physiology And Root Proteome Of Lowland Rice And Upland Rice

Rice (Oryza sativa L.) as one of the most important food crops, is thestaple food for more than50%of the population. With the aggravate tension of theglobal warming, areas of the national crops affected by drought stress expandunceasingly, which has seriously affected the yield and quality of rice. That is to say,drought has become the long-term existent factors of the major abiotic stress on riceproduction. Therefore, analysizing the reaction mechanism of drought stress on riceand increasing the ability of drought resistance of rice have important applied value innational food security. An upland rice introgression line (IL392) and a lowlandcultivar (YueFu), an upland cultivar (IRAT109) with significant difference betweendrought resistance and root traits were used for this study. Six-leaves old seedingswere treated with PEG-6000for imitating drought. The physiological responses todrought stress and proteome of root were studied. The results are as follows:1、Effect of drought stress on the physiological indexes of upland and lowland riceAfter drought stress, relative water content and root volume decreased, whileSOD, POD and soluble protein content increased. Through the analysis of theindicators of the three materials, IRAT109and IL392have a bigger root length andvolume, smaller decrement of relative water content and root volume. In addition,later period of drought stress, YueFu’s PSII suffered irreversible damage, while thedamage of IRAT109and IL392is repairable. So IRAT109and IL392have thestronger drought resistance than lowland rice YueFu owing to the developed rootsystem and strong ability of root water retention.2、Appropriate method for rice root protein extractionRice root protein were respectively extracted by the improved TCA/acetone/SDS method, TCA/acetone method, and TCA/acetone/Tris-HCL method, then thoseproteins used for two-dimensional electrophoresis. It turned out that the improvedmethod of TCA/acetone/SDS is appropriate for rice root proteome analysis, and theloading quantity of350μg appeared to be better for getting2-DE map with highdefinition, repeatability and better separation.3、Analysis of root proteome of lowland rice and upland riceAfter0,9,18,24,48hours’ treatment, root of IRAT109and YueFu were obtained respectively. Root protein was extracted for two-dimensional electrophoresis.There were approximately420protein spots detected on the two-dimensionalelectrophoresis maps. Forty-four protein spots changed significantly. Among theforty-four protein spots, thirty-one protein spots were associated with genotype andnineteen protein spots were related to drought stress.42protein spots were identifiedby MALDI-TOF/TOF MS analysis. Functions of identified protein spots involved inthe metabolism of carbohydrates, signal transduction, oxidative stress, energymetabolism, amino acid metabolism, nucleic acid binding and protein binding.Among the six function classes, proteins correlated with carbohydrate metabolismaccounted for38.10%, which was the largest proportion. Through analyzing theseproteins’ metabolic pathways, we found that more than50%of the proteins involvedin secondary metabolism.4、Comparative proteome analysis of introgression lines rootsRoot proteome of IL392at different treated times was compared with the CK,twenty-five protein spots changed significantly. Through proteome analysis of threematerials, thirteen spots had significant difference between IL392and YueFu, whichhad no significant difference between IL392and IRAT109. At the same time, thesethirteen spots were the significant different spots between YueFu and IRAT109.Functions of the thirteen spots involved in the metabolism of carbohydrates, signaltransduction, oxidative stress, energy metabolism and amino acid metabolism. Amongthe five function classes, proteins correlated with carbohydrate metabolism was thelargest proportion, followed by oxidation of defense related proteins.Our study shows that the developed root system, a stronger ability to retain water,and drought signal transduction, energy metabolism, antioxidant system relatedproteins’ high expression, synergy of these a few aspects allow the upland riceIRAT109and introgression lines IL392have a stronger drought resistance ability.This study lays the foundation of analysis for drought resistance mechanism, whichhas very important significance for drought-resistant breeding and practice.