Molecular Marker For De-cucumber Blooming And Response Mechanism Of Low Temperature Stress Ofpumpkin Rootstocks

Cucumber(Cucumis sativus L.)is one of the main facilit cultivation vegetables.Bloom on fruit surface is an important commodity character of cucumber,the content of the bloom on the grafted cucumbers with different rootstocks were different,in which the silicon metabolism in roots plays a important role.In order to develop the molecular marker of rootstock cultivar for de-cucumber blooming,thefragment of silicon transporter gene CmLsi1 was cloned from pumpkin rootstocks with different ability to extract cucumber bloom,and there was a single nucleotide polymorphism(SNP)site at 224 bp.In this study,a CAPS/HinP1?molecular marker which was based on the SNP site of the CmLsi1 gene was developed.We used this molecular marker toverify the individuals of pumpkin rootstocks,and the result showed that the accuracyof the molecular marker was up to 95.24%,the Pearson bilateral correlation analysis showed thatthe marker was significantly correlated with de--cucumber blooming ability of pumpkin stocks.Therefore,this CAPS marker is suitable and reliable to identify de-cucumber blooming ablity of pumpkin rootstocks.Low temperature is one of the main abiotic stress factors limiting the yield and quality of cucumber.Grafting pumpkin rootstocks can improve the cold tolerance of cucumbers.In order to breed pumpkin rootstock with low temperature tolerance,the seed germination index,physiological and biochemical propertiesof 'Qingzhen No.1','Weizhen No.1' and 'Beigua' under low temperature(15°C/10°C)stress was studied.(1)Under low temperature treatment,the germination rates of 'Qingzhen No.1'','Weizhen No.1' and 'Beigua' seeds decreased significantly,the germination index decreased by 48.89%,53.60% and 35.00%.(2)Under low temperature stress,the malondialdehyde(MDA)of 'Qingzhen No.1' and 'Weizhen No.1' increased at first and then decreased,the MDA of 'Beigua'first increased and kept stable finally.The time when the MDA in the 'Beigua' increased significantly earlier than 'Wei zhen No.1' and 'Qingzhen No.1'.(3)The proline of 'Qingzhen No.1' increased at all time,the proline of ‘Weizhen No.1' and 'Beigua' increased at first,then decrease and increase at last.The time when the proline in the 'Beigua' was conspicuously high earlier than 'Wei zhen No.1' and 'Qingzhen No.1'.(4)The soluble sugarof 'Qingzhen No.1','Weizhen No.1' and 'Beigua'first increased and then maintained higher level,the time when the soluble sugar in the 'Qingzhen No.1' and 'Beigua' increased earlier than 'Wei zhen No.1'.(5)The peroxydase(POD)activity of 'Qingzhen No.1','Wei zhen No.1' and 'Beigua' always increased,the response of POD activity in 'Qingzhen No.1' and 'Wei zhen No.1' were earlier than 'Beigua'.(6)The activity of superoxide dismutase(SOD)on 'Qingzhen No.1' had continued to rise,SOD activity of Wei zhen No.1' and 'Beigua' increased first and then decreased.SOD responsemechanism of 'Qingzhen No.1','Weizhen No.1' and 'Beigua'were significant different under low temperature stress.(7)The catalase(CAT)activity of 'Qingzhen No.1','Wei zhen No.1' and 'Beigua' always increased,the response of CAT activity in 'Qingzhen No.1' was earlier than 'Wei zhen No.1' and 'Beigua'.Soluble sugar content,SOD,POD,and CAT activity were related to each other,the obtained results of cold tolerance were consistent with field identification results.Therefore,soluble sugar content,SOD,PODand CAT activity were the suitableindexes to evaluate the cold tolerance of pumpkin rootstocks,this study provide a theoretical basis for breeding of pumpkin rootstocks with low temperature tolerance.