Study On Storage Traits Of Landrace Of Cucumis Sativus Var.Xishuangbannaensis

Cucumis sativus var.xishuangbannaensis has been cultivated for many generations by ethnic people in mountainous areas of Xishuangbanna Prefecture and neighboring region.It has become a significant crop landrace with its specificity in local communities.As an agricultural crop resource,it is of great significance to local people’s livelihood and sustainable development of agricultural ecosystem.To indicate the importance of this germplasm resource,a study on storage traits of Xishuangbanna cucumber has been conducted:(1)Assessment of the Resilience in SEPLS(SocioEcological Production Landscapes and Seascapes)in Yanuo Village,Xishuangbanna,Southwest China has been made for study on the local traditional ecosystem.The results revealed that the traditional ecosystem in Xishuangbanna was rich in diversity,which is composed of ancient tea gardens,homegardens,rubber and cash crop plantation,fish pond,medicinal plants,and other wild plants and cultivated crops.There are more than 30 ethnic groups with rich traditional knowledge and culture living in the mountainous areas of Southwest China for a long time.Historically,Jinuo people were famous for swidden cultivation and slash-and-burn agriculture.The rotation system is still a valuable management strategy for the sustainable development of the agricultural ecosystem.By planting tea seedlings under natural forest,a tea-forest ecosystem has been formed with stability.As a result of the adaptability to the traditional ecosystems,Xishuangbanna cucumber has become an important landrace.(2)The ethnobotany investigation of Xishuangbanna cucumber landrace was carried out.Its fruit is characterized by shelf life and delicious flavor.It is also the carrier of traditional knowledge and culture for local comunities.Only a few households in the remote and high-altitude mountainous villages continue to cultivate very limited amounts of Xishuangbanna cucumber landrace for family consumption.The genetic resources of Xishuangbanna cucumber landrace and the associated traditional knowledge and culture have suffered rapid decline.It is suggested that on-farm conservation should be adopted to protect both the genetic resources of Xishuangbanna cucumber landrace and the associated traditional knowledge and culture.(3)The results of the optical microstructural analysis showed that the pericarp structure of Xishuangbanna cucumber landrace was significantly different from that of modern cucumber varieties.The epidermal cells of epicarp were closely arranged with a high degree of lignification.Therefore,it can effectively resist external interference,enhancing the ability of disease resistance and insect pests,which is conducive to the extension of the storage period.No β-carotene was detected in modern cucumber varieties,while the content of β-carotene was high in Xishuangbanna.The orange color of pulp is mainly due to the accumulation of β-carotene.Proline,an important amino acid for plants to respond to environmental stress,was only detected in Xishuangbanna cucumber landrace.(4)The aromatic components of Xishuangbanna cucumber pulp were identified and analyzed by GC-MS.A total of 129 differential metabolites were identified(cucumber Line 9930 as control group).Compared with the cucumber Line 9930,the contents of 34 metabolites in Xishuangbanna cucumber were significantly increased.According to the LIPID MAPS,36 metabolites were functionally annotated as fatty acids and 2 metabolites as prenol lipids.(5)Based on LC-MS,the metabolic components of different parts of Xishuangbanna cucumber landrace identified.The metabolic components of peel and pulp of Xishuangbanna cucumber were identified and screened(cucumber Line 9930 as control group).In the positive ion mode,the total number of differential metabolites between Xishuangbanna cucumber landrace and Line 9930 were 181 and 205,in pulp and pericarp respectively.There were 226 different metabolites between Xishuangbanna cucumber landrace pulp and pericarp.In the negative ion mode,the total number of differential metabolites between Xishuangbanna cucumber landrace and Line 9930 were 149 and 181,in pulp and pericarp respectively.There were 176 different metabolites between Xishuangbanna cucumber landrace pulp and pericarp.According to the LIPID MAPS,19 metabolites were functionally annotated as fatty acids,26 as polyketides,6 as prenol lipids,and 10 as sterol lipids,in the positive ion mode.There were 31 metabolites functionally annotated as fatty acids,22 as polyketides,8 as prenol lipids,and 8 as sterol lipids,in the negative ion mode.Significantly,KEGG enrichment analysis of the differential metabolites demonstrated that there are compounds in Xishuangbanna cucumber which can enhance plant resistance.The traditional agricultural ecosystem that was the habitat of Xishuangbanna cucumber landrace was investigated in the present study.By comparing with improved cucumber variety(line 9930),the mechanism of storage tolerance,resistance to diseases and pests of Xishuangbanna cucumber landrace was revealed from the micro-morphological and biochemical levels.The results of this study are significant for the conservation and utilization and related traditional knowledge of Xishuangbanna cucumber landrace.It also provides the development ideas for the conservation,breeding and sustainable utilization of genetic resources of other landraces.