Proteomics And Rhizosphere Microflora Of Millet / Peanut

Intercropping has been widely applied and closely concerned because of the advantage in yield. Gramineae/leguminosae intercropping system is a successful model. Appropriate intercropping of different crops can supply more nutrition, enhance the utilization of light, facilitate resistance to pathogen, and improve fertility of soil. However, the protein expression profile of intercropping crops has not been deeply researched, and the understanding of intercropping in molecular level largely remains known.In this research, the yield variation, protein profile and rhizosphere soil microbial community structure were investigated under the millet/peanut intercropping system to discuss the mechanism of yield increasing effect. Results showed that, the dry weight and yield of intercropped millet and peanut was significantly increased. The yield of mesh barried millet fall in the middle of intercrop and monocrop. The yield of mesh barried peanut showed no significant difference with intercropped peanut, while was significant higher than monocropped peanut. These results indicate that intercropping of millet with peanut can increase the yield of both crops.The protein differenical expression among millet and peanut leaf among intercrop, mesh barry and monocrop was compared using quantitative proteomics method based on two dimensional electrophoresis. In millet leaf, compared to the monocrop, 9 proteins up-regulated and 6 proteins down-regulated in intercrop,7 proteins up-regulated and 5 proteins down-regulate in mesh barry. In peanut leaf, compared to the monocrop,16 proteins up-regulated and 2 proteins down-regulated in intercrop,14 proteins up-regulated and 3 proteins down regulated in mesh barry. Most of the up-regulated proteins in intercrop and mesh barry crops involved in photosynthesis. And these proteins involved in photosynthesis were verified in mRNA level by qPCR. The results showed that the difference between protein level and mRNA level was basically consistent. The results of leaf proteomics showed that the photosynthesis of leaf was greatly enhanced and thus the crop can obtain more carbohydrate.The protein differenical expression among millet and peanut root among intercrop, mesh barry and monocrop was compared using quantitative proteomics method based on TMT labelling technology. In millet root, compared to the monocrop,40 proteins up-regulated and 24 proteins down-regulated in intercrop,29 proteins up-regulated and 13 proteins down-regulated in mesh barry. In peanut root, compared to the monocrop,12proteins up-regulated and 24 proteins down-regulated in intercrop,8 proteins up-regulated and 8 proteins down-regulated in mesh barry. Further bioinformatics analysis showed that:a) In millet root, the proteins involved in carbohydrate synthesis, endoplasmic reticulum protein metabolism, substance transportation and signal transduction were up-regulated, such as urease and inorganic phosphate transporter which has important role in N, P metabolism. Our data revealed that the root of intercropped millet could supply more elements for the crop although some proteins involved in resistance to pathogen were down regulated.b) In peanut root, those proteins involved in embryonic development, seed maturation, transport and stress response were up-regulated, some proteins involved in lipid biosynthesis were down regulated.c) Besides this, in the part of plant defense, the phenylalanine/tyrosine ammonia-lyase, peroxidase, laccase and chitinase which corelated closly with pathogen passive defense were down regulated in intercropped millet root, and the lipoxygenase which is the key enzyme in jasmonic acid biosynthesis were down-regulated in intercropped peanut root. That indicated that the disease in the root of intercropped plant was decreased to a lower level.d) However, the mesh barried plants still had some active resistance related proteins which were up regulated. For example, the acidic endochitinase and mannose/glucose-binding lectin was up-regulated in mesh-barried peanut root. These results showed that the mesh barried peanut had the ability to defense pathogen.According to the differential expressed protein, the nutrition utilization efficiency of intercropped millet and peanut was improved, and the biotic stress to the plant was alleviated. It can be concluded that the intercropped plants enhance active defense and reduce the induce defense. As for the most important, it is increasing more energy to the material accumulation.The expression difference of proteins involved in transport and pathogen defense was validated with the qPCR experiment. The results showed that the difference in protein level and mRNA level was basically consistent.We also analyzed the variation of rhizosphere soil microbial community structure of millet and peanut with Biolog and T-RFLP technologies in this study. Results showed that the rhizosphere soil microbial community structure of intercropped plants was significantly changed, especially for the peanut. Compared to monocropped plants, the diversity and evenness index of rhizosphere soil microbial community was greatly enhanced. In intercropped plants, the number of Actinobacteria was increased, thus the soil fertility was improved. Some biocontrol speices such as Bacillus and Streptomyces increased in intercropped plants soil, while some pathogens such as Spiroplasma deceased in intercropped plants soil.In summary, in the millet/peanut intercropping system, the photosynthesis of leaf and the acquisition of N, P element of root were improved, thus the biosynthesis and substance accumulation of plant was promoted as well. In the rhizosphere soil, the microbial community structure has more biodiversity, and the number of beneficial bacteria was increased, and the pathogen was decreased. Thus, the intercropping could promote the soil microbial community structure, and enhance the plant grow.