The Preliminary Study Of Nodulation Influencing The Drought Resistance Of Grass Pea(Lathyrus Sativus L.)

Drought stress is one of the main abiotic factor influencing agriculture, which significantly limits agricultural productivity under serious water deficit condition. It has been reported that nodulation can provide principal N nutrition for legume through fixing atmospheric nitrogen. Because of its excellent resistance and nitrogen fixation ability, grass pea was cultivated widely in arid and semi-arid regions all over the world, and was regarded as food and animal fodder in some low-income and food deficit areas. To date, little is known on the relationship between nodulation and crop drought resistance, and never has been reported in grass pea. This work aimed to determine whether nodulation effects the physiological adaptation to drought stress in grass pea. Furthermore, we have investigated the possible mechanism of nodulation influencing the drought resistance in grass pea. It can provide basis for screening drought resistant strain and scientific instruction for agricultural development. Several physiological and biochemical methods, such as histocyte microexamination, antioxidant system analysis, high performance liquid chromatography (HPLC) etc., were used in this study to investigate how the nodulation influencing drought resistance of grass pea, The results obtained in this study are as followed:1. Nodulation ability of Yong Shou grass pea was better than that of A’Ma and Bian Jia grass peas; The excellent nitrogen fixation ability was closely linked with the spiral vessel of grass pea.2. The rhizobia separated from grass pea was Rhizobium leguminosarum.3. The relative water content (RWC) in nodulated grass pea was 62%, but no-nodulated grass pea was 45% after drought stress; The content of MDA in nodulated grass pea was 0.58 nmol g-1 fwt, which was less by O.llnmol g-1 fwt than that in no-nodulated grass pea. That indicated nodulation could alleviate the damage by drought stress.4. The contents of O2- and H2O2 were 0.28μmol g-1 fwt and 1.5μmol g=1 fwt respectively, in nodulated grass pea, but the O2= and H2O2 contents were respectively 0.35μmol g-1 fwt and 1.8μmol g-1 fwt in no-nodulated grass pea after drought stress.5. The contents of enzymatic antioxidants and non-enzymatic antioxidants were detected in this research, such as superoxide dismutase(SOD), ascorbate peroxidase(APX), catalase(CAT), ascorbic acid(AsA), glutathione(GSH) and proline. The results showed that the activities or contents represented positive correlation with the contents of O2- and H2O2, and the contents of antioxidants were higher in no-nodulated grass pea than that in nodulated grass pea after drought stress. Some antioxidants indicated extremely significant difference between nodulated and no-nodulated grass pea.6. In ground parts, the content of β-ODAP was 12mg g-1 fwt in nodulated grass pea, but was 10.5 mg g-1 fwt in no-nodulated grass pea; However, the contents of β-ODAP were no notable difference in roots, which was only about 0.3 mg g-1fwt.7. The level of abscisic acid (ABA) was 2.2μg g=1 fwt in nodulated grass pea after drought stress, but was 3μg g-1 fwt in no-nodulated grass pea, which indicated nodulation could decrease the content of ABA.All of the results mentioned above imply that it appears to be the same rhizobium which nodulated in different varieties of grass pea. But it also represents specificities in nodulation and nitrogen fixation; Nodulation can decrease the contents of ABA, ROS and antioxidants through limiting water loss in grass pea under drought stress, and then prevent grass pea from wilting even death; Meanwhile, the content of β-ODAP in nodulated can be increased, which also improved the drought resistance of grass pea.