Storage Ability And Proteomic Analysis Of Post-Harvest Tuberous Roots Of Cassava

Cassava(Manihot esculenta Crantz) is thesixth largest crop in the world behind wheat, rice, corn, potato, and barley.It isa staple food for more than800million people.However, the rapiddeterioration after cassava post-harvest severely limits the cassava development in processing. Therefore, it is necessaryto understand the molecular mechanism influencing cassava post-harvest deterioration.Four cassava varieties including SC5, SC8, SC9and SC11were used as the research materials to understand the relation of the biophysiochemical characteristics during storage of cassava tuberous roots in the present study. By comparison of the weightlessness rate, dry matter content, starch content and beta carotene contentat different growth period in four cassava varieties, the results indicated that there are significantly differences between the biophysiochemical characteristics of four varieties. The dry matter content and starch content in the first7days of storage showed a significant correlation in the four varieties.The results showed that SC5is the best variety for storage in normal temperature. The differentially expressed proteins maps of cortex and flesh from cassava SC5tuberous roots after15d-storage at normal temperature were established using2-dimensional electrophoresis.78differential expressed protein spots were detected from cortex of cassava tuberous roots, including9up-regulated spots and69down-reguated spots;60differentiall expressed proteins apots in flesh containing43up-regulated spots and17down-regulated spots. The identification of differentially expressed protein spots was using MALDI-TOF-TOF-MS/MS.52of these differentially expressed proteins were successfully identified, in which43proteins from flesh are divided into11groups including carbohydrate and energy metabolism, amino acid metabolism, cell structure, signal transduction, antioxidation, protein biosynthesis and etc.24proteins from cortex are involved in nine functional groups.In order to better understand the biological functions of these differential expressed protein groups in regulation of post-harvest storage of cassava tuberous roots, a biological network of protein-protein interactions was established using a Pathway Studio software developed by Ariadne. The results indicated that the protein regulation is a complicated process conducted together by lots of protein complexs. In the network, NADH-oxdiase can catalysethe process of producing ROS. It is known that ROS, a signal molecule, is one of important regulations in the biological network of protein-protein interaction. In the present study lots of ROS producing from activities of NADH-oxdiase will induce the up-regulation of Calmodulin. Many biological defense reactions will be started up through the calmodulin as a key point, and then increasing the expression levels of dehydrin and annexins etc and improve the resistant ability against the storage. The present study will provide an insight into understanding of moleculat mechanism of post-harvest deterioration of cassava tuberous roots and improve the varieties using proteomic techniques.