Preteome Analysis On The Effect Of Nodules On Alfalfa (Medicago Sativa L.) Dehydration Tolerance

In the present study, we use iTRAQ technology to conduct proteomics analysis on alfalfadrought-resistant ability of different rhizobiaon treatments in drought conditions, based on thestudies of drought-resistant physiology of alfalfa with nodules symbiosis in our laboratory,aims to elucidate protein response mechanism of alfalfa with nodules symbiosis in droughtconditions.The results are as follows:1. On the ground part of the3032proteins were identified. There was a small number ofdistinct proteins in overground parts treated with activated nodules, with inactivated nodulesand no nodule under light drought and modest drought, which were mainly involved in themetabolic pathways of oxidative phosphorylation, photosynthesis, ribosomes and RNAtransport. Two proteins including ATP synthases involved in oxidative phosphorylation andphotosynthesis and eukaryotic translation initiation factors participated in the ribosomeprotein and RNA transport were both up-regulated in the treatment of with activated nodules.This demonstrated that energy demands of alfalfa with activated nodules were elevated, theexpressions of genetic material have changed under drought stress.2. On the underground part of the3379proteins were identified. The distinct proteinswere significant more in underground parts. In the treatment with activated nodules,3ribosomal proteins related to ribosome process were up-regulated under light drought while4were up-regulated under heavy drought, which shows activated nodules inoculation increasedthe protein synthesis amout and rate of alfalfa under drought stress. However, no significantup-regulation were observed in distinct proteins associated with organic metabolism, energymetabolism and antioxidative process in the same treatment, illustrating that alfalfa withactivated nodules probably synthesize some other related proteins to improve their droughtresistance, which is needed to further study.In summary, under drought stress, the aboveground of the alfalfa with activated nodulesless sensitive to drought, mainly through energy metabolism to resist drought. Theunderground part was sensitive to drought, and differential protein quantity, mainlyconcentrated in the ribosome pathway, indicating underground part of protein synthesis increased. Therefore, we need to focus on the underground portion of the protein underdrought stress response mechanism to reveal the alfalfa with activated nodules improvedrought resistance mechanism, which requires more in-depth exploration and research.