Biomarker Development For Storage Life Predicting In Satsuma Mandarin(Citrus Unshiu Marc.)

Citrus is the world’s largest fresh fruit among global fruit industry, which has a long storage period during postharvest stage. In order to ensure the fruit quality during storage, predicting the physiological state after harvest is therefore particularly important, which can not only enrich the basic theory of citrus postharvest biology, but also resolve the risk of deterioration in large-scale during citrus fruit storage. Based on the microarray and primary metabolites data of Satsuma mandarin during 0-50 DAH(days after harvest), approaches of hierarchical clustering, principal component analysis, partial least squares discriminant analysis and support vector machine model were integratively used to gain insight into different physiological status and to mine representative biomarker candidates representing citrus fruit storage process. Additionally, the high reliability of transcriptome data was verified by q RT-PCR. The main results are as follows:According to bioinformatics analysis of microarray and primary metabolites data, the post-harvest storage process of Satsuma mandarin could be classified into three physiological stages: stage 1, early stage of post-harvest storage, stage 2, fruit bringing the best flavor characters, and stage 3, the terminal stage of fruit storages. Analysis of microarray data and results of Real-time PCR indicated that the quantitative expression values of glutathione S-transferase(Cit.15371.1.S1_at) ranged from 0.8 to 1.0 at early storage phase, 0.7-0.8 at the stage of best flavor and below 0.7 at the terminal storage stage respectively. The expression trend of glutathione S-transferase has obvious stage characteristics, and therefore it can be used as a biomarker evaluating Satsuma mandarin post-harvest storage status. Through data analysis of metabolites, we could find that the contents of Glycine, 3-Amino-6-methoxypicolinic acid, 2-Butenedioic acid, Cyclohexanone,2-[(dimethylamino)methyl]- experienced a stage change. At the early storage phase, the content of the four metabolites stood at a high level. Then it declined significantly and maintained at low level in the phase of best flavor fruit. To the late period of storage, the content of the four components increased significantly. Taken together, we deduced that they could be used as candidate metabolite biomarkers to predict citrus storage status.