Identification Of Cold Resistance And RAPD And ISSR Markers Linked To Cold Resistance Genes In Loquat

In this study,7cultivars (lines), including’Chuannong NO.1’,’Chuannong No.2’,’Dawuxing’,’4-1-11’,’6-3-10’,’6-4-10’,’6-6-10’, were used for the experimental material. Young fruits were treated at0℃,-3℃,-6℃and7℃for12h,24h and48h. The physiological and biochemical indices, including the electrolyte leakage, MDA content, Pro content and SOD activity, were measured to reveal the cold hardiness of the materials. Through principal component analysis and subordinate function method, a comprehensive evaluation of cold resistance of the materials was given. At the same time, the molecular markers linked to cold resistance genes were studied by random amplified polymorphism DNA (RAPD) and inter simple sequenee repeats (ISSR). The main results are summarized as follows.(1)The change pattern of physiological and biochemical indices in pulps and embryos of7materials were basically same under cold treatment. The electrolyte leakage, MDA content were the lowest, and its SOD activity, Pro content were the highest in either the pulp or embryo of’6-3-10’. On the contrary, the electrolyte leakage, MDA content were the highest, and other physiological and biochemical indices were the lowest in the pulp and embryo of’Chuannong NO1’. The others were between them and ranked by’6-4-10’>’4-1-11’>’6-6-10’>’Dawuxing’>’Chuannong NO2’in cold resistance.(2) According to logistic equations, the half lethal temperatures of the pulps of the7materials were-3.21℃,-6.01℃,-6.23℃,-6.35℃,-6.71℃,-6.59℃and-6.26℃, respectively; the half lethal temperatures of the embryos of the7materials were-3.53℃,-5.65℃,-6.35℃,-6.56℃,-6.82℃,-6.73℃and-6.47℃, respectively. There was a negative correlation between the cold resistance and electrolyte leakage, the half lethal temperature and MDA content, while there was a positive correlation between the cold resistance and SOD activity and Pro content.(3) A closer relationship was present between the cold resistance and protective enzymes, cell membrane permeability and lipid peroxidation in the component analysis.(4) Either the pulp or embryo, the cold-resistance ability of the7materials was ’6-3-10’>’6-4-10’>’4-1-11’>’6-6-10’>’Dawuxing’>’Chuannong No.2’>’Chuannong No.l’based on subordinate function values analysis.(5)The RAPD marker of OPA16-1200bp gene of1loquat cold-resistant strains may be linked to in loquat.(6) Using ISSR marker UBC857-600, a specific band was amplified in the6materials except’6-3-10’.