ISSR Analysis Of Pitaya (Hylocereus Undatus) Germplasm Resources From Fujian Province And The Study Of Salt-Tolerance Physiology

In this experiment, the20germplasms of pitaya (Hylocereus undatus) which werecollected from Fujian Province were utilized as materials, and the techniques ofInter-Simple Sequence Repeat markers (ISSR) were performed to study the geneticdiversity in pitaya. To explore different varieties of salt resistance levels,5pitayacultivars (strains) which were selected from cluster result and biological characteristicwere under sodium chloride stress. The main results were as follow:1. The tender stem of tipaya were utilized as materials, a stable ISSR-PCRreaction system of pitaya was established. The results showed that the optimumconcentrations of components in20μL reaction system were2.0μL10×Buffer(including Mg²⁺),20.0ng template DNA,0.30mmol·L^-1dNTP,0.35μmol·L^-1primerand1.5U Taq DNA polymerase.2.11ISSR primers were selected from96random primers, the ISSR-PCRamplification was used on20individuals of cultivated pitayas, and142scorableamplification sites were detected which include106(74.65％) polymorphic sites. Basedon SPSS l8.0analysis,the similarity coefficients between different cultivars rangedfrom0.478to0.937, and the average genetic similarity coefficients was0.646. Thedifferent strains and different sources of pitaya could be divided by Jaccard clustering.5pitaya cultivars (strains) which were selected from cluster result were utilized asphysiological studies for salt resistance, to some extent it could shorten the breedingprocess.3. The cutting potted pitaya seedlings of Hylocereus undatus. cv.'haibai1'(H₁)were used as material for the study on the changing tendency of physiological index inthe tender stem under the stress of NaCl with mass fractions of0.4%,0.8%and1.2%,respectively. The results showed that: the physiological index of pitaya tender stem didnot change significantly except later period when under stress of0.4%NaCl. Therelative conductivity, content of MDA and soluble saccharide, and the activity of SOD,POD and CAT were significantly increased under stress of0.8%NaCl, but Pro contentchanged erratically. Under stress with1.2%level of NaCl, the relative conductivity, content of MDA and Pro were significantly increased in prophase. The content ofsoluble saccharide showed the trend of declining-rising-declining. And the SOD, PODand CAT activity raised up remarkable in prophase, but the activity were decreased inlater period.4. To explore different varieties of salt resistance levels, the cutting potted pitayaseedlings of H₁, Hylocereus undatus. cv.'baijulong'(B), Hylocereus undatus. cv.'chilong'(C), Hylocereus undatus. cv.'julong'(J), Hylocereus undatus. cv.'hongxianmi'(H) were used as material, the physiological changes were studied understress of1.2%NaCl solution. The results showed that the performance of differentcultivars were dissimilar under salt stress. The white flesh cultivars' sequence of thesalt resistance is H₁>B. And in the red flesh cultivars, C was stronger than the others,but there were no significant differences between J and H. So directly through singlephysical index could not distinguish the salt tolerance level from different varieties ofpitayas.5. Through the principal component analysis, three principal components wereextracted in which could explain97.34%of the original variables information. And theappraisal system of salt resistance was set up by the principal component analysis.Through the appraisal system,the five pitayas' salt tolerance levels were ranked, andthe sequence were as follow: C> H₁> J> B> H.