The physiological and molecular mechanisms of N transfer in Eucalyptus and Dalbergia odorifera intercropping systems using root proteomics

Background The mixing of Eucalyptus with N2-fixing trees species (NFTs) is a frequently successful and sustainable cropping practice. In this study, we evaluated nitrogen (N) transfer and conducted a proteomic analysis of the seedlings of Eucalyptus urophylla × E. grandis (Eucalyptus) and an NFT, Dalbergia (D.) odorifera, from intercropping and monocropping systems to elucidate the physiological effects and molecular mechanisms of N transfer in mixed Eucalyptus and D. odorifera systems. Results N transfer occurred from D. odorifera to Eucalyptus at a rate of 14.61% in the intercropping system, which increased N uptake and growth in Eucalyptus but inhibited growth in D. odorifera. There were 285 and 288 differentially expressed proteins by greater than 1.5-fold in Eucalyptus and D. odorifera roots with intercropping vs monoculture, respectively. Introduction of D. odorifera increased the stress resistance ability of Eucalyptus, while D. odorifera stress resistance was increased by increasing levels of jasmonic acid (JA). Additionally, the differentially expressed proteins of N metabolism, such as glutamine synthetase nodule isozyme (GS), were upregulated to enhance N competition in Eucalyptus. Importantly, more proteins were involved in synthetic pathways than in metabolic pathways in Eucalyptus because of the benefit of N transfer, and the two groups of N compound transporters were found in Eucalyptus; however, more functional proteins were involved in metabolic degradation in D. odorifera; specifically, the molecular mechanism of the transfer of N from D. odorifera to Eucalyptus was explained by proteomics. Conclusions Our study suggests that N transfer occurred from D. odorifera to Eucalyptus and was affected by the variations in the differentially expressed proteins. We anticipate that these results can be verified in field experiments for the sustainable development of Eucalyptus plantations.

The Phylogenetic Analysis and Identification of a Novel Remorin Member from Rice(Oryza sativa L) by Proteomics under Salt Stress

Rice root proteomics research identified to a new remorin1 protein,named OsREM1,which significantly increased (approximately 1.7-fold) compared with control under salt stress by Two-dimensional electrophoresis. It is found that the protein molecular weight is 29 kD, isoelectric point is 4.54. The bioinformatics analysis showed that: (1) The protein contains 195 amino acids, whose theoretical molecular weight is 21.3 kD, whose theoretical isoelectric point is 5.06. There are some differences with the experimental results, which may be the result of post-translational modification, such as glycosylation, phosphorylation; (2) The different crop remorin protein sequence alignment analysis found that the same rate of the amino acids is more than 50%, indicated that remorins are highly conserved protein; (3) Phylogenetic analysis showed OsREM1 had a low sequence identity with potao and tomato REM1, which is the agreement with traditional classification.