Mechanism Of SbTRXh1and Sb14-3-3Gene In Regulating The Cold-induced Sweetening Of Potato Tubers

In fried potato processing industry, harvested potato tubers usually need low temperature storage to reduce damages caused by desiccation shrinkage, infection of plant diseases and insect pests, decay and germination of tubers, and ensure supply for the anniversary. But in the process of low temperature storage, the potato tubers will appear cold-induced sweeting phenomenon that accumulation of reducing sugar content, and excessive reducing sugar in potato tubers after cold-induced sweeting make the potato chip deepened color, become poor taste and produce harmful substance such as acrylamide after high temperature fry. All of these are very harmful to potato processing quality. Preliminary experiments of our laboratory showed that, after interference of SbTRXhl or Sb14-3-3genes and4℃treatment for30days, compared with controlled cultivation of Hubei potato variety NO.3(E3) of non-gm line, reducing sugar content in potato tubers of gm lines after cryopreservation significantly reduced, but specific mechanism of cold-induced sweeting of SbTRXhl or Sb14-3-3genes to potato tubers is not very clear yet.This study through metabolomic analysis of gm SbTRXhl or Sb14-3-3gene interference lines and Hubei potato variety NO.3of controlled cultivation of non-gm line, combined with related enzyme activity analysis in the process of starch and sugar metabolism. The main results were as follows:1. Through analysis of primary metabolites of processing tubers with4℃,30days by GC-MS/MS method, it found that compared with primary metabolites content of the non-gm line E3tubers that processed in the same period, most of the metabolites content of SbTRXh1gene interference lines in tubers gluconeogenesis pathway decreased significantly. In the same time, through measuring enzyme activity of processing tubers with4℃,30days, it found that compared with primary metabolites content of the non-gm line E3tubers that processed in the same period, fructose-1,6-bisphosphatase of gm SbTRXhl gene interference lines tubers decreased significantly. Thus it speculated that changes of SbTRXhl gene expression would change the pathways of gluconeogenesis and tricarboxylic acid cycle. In addition, by measuring the respiratory rate of tubers with4℃,30days, it confirmed that after4℃,30days low temperature storage process experiment, respiration of gm SbTRXhl gene interference lines tubers got inhibition compared with the non-gm line E3. Moreover, RNAi lines’tubers invertase activity is also inhibited in4℃,30days.2. By measuring enzymes’activity of tubers of gm Sb14-3-3gene interference lines and non-gm line, it found that after30days4℃low temperature storage processing, compared with non-gm line E3that processed in the same period, invertase activity of gm Sb14-3-3gene interference lines tubers decreased significantly. In addition, activity of ADP-glucose pyrophosphorylase and sucrose phosphate synthase in gm Sb14-3-3gene interference lines tubers increased significantly, compared with non-gm line E3that processed in the same period. Thus it speculated that RNAi of Sb14-3-3gene affected sucrose degradation and synthesis of glucose and fructose in tubers, and then affected the reducing sugar content in the tubers during low temperature storage. Addtionly, through analysis of primary metabolites of processing tubers with4℃,30day, it finds that lines of RNAi of Sb14-3-3contents of amino acid mostly increase, it suggests that Sb14-3-3gene may contribute in metabolism of amino acid.