| At present, the kiwifruit has become one of important economic fruit trees in China.Shaanxi province is a largest cultivation area province of kiwifruit, so the kiwifruit industrydevelopment of Shaanxi plays a decisive role in kiwifruit industry development in China. Inrecent years, the occurrence of Shaanxi kiwifruit bacterical canker in main planting area, hadhave a great influence on the development of kiwifruit industry.This study, first the pathogenic bacteria of kiwifruit canker was separated and purified inmain planting area of Shaanxi Qinling north piedmont mountains, and the molecularidentification and pathogenicity identification were carried out. Secondly,18kiwifruitmaterials were investigated in field, inoculated artificially in vitro and potted branches withpathogen.The infected rate of branches were observed in5,10,15,20days after inoculation,and the resistance results were compared among three resistance identification methods. Atthe same time, a total of five period branch samples were collected from the potted kiwifruitof ‘Maohua’,‘Jinkui’,‘Huayou’,‘Jintao’,‘Red sun’ after inoculation0,5,10,15,20d.Theactivity changes of phenylalanine ammonia enzyme (PAL), superoxide dismutase (SOD),catalase (CAT), polyphenol oxidase (PPO), polyphenol oxidase (POD) were determinedwithin different inoculation time branches. Finally, a DNA marker linked to the cankerdisease resistance gene in kiwifruit was explored by simple sequence repeat (SSR) techniquecombined with bulk segregation analysis (BSA) using the population of198progenies of‘Xixuan No.2’ and‘SX45872’. The main results were as follows:1. The molecular identification results of purification kiwifruit canker pathogen inShaanxi Qinling north piedmont mountains, showed that the pathogen was Pseudomonassyringae pv. actindiae, and16S rDNA sequences of it were consistent with other reported16S rDNA sequences of kiwifruit canker pathogen. The pathogenicity identification resultsshowed that this pathogen could infect kiwifruit.2. The resistance identification results in vitro and potted with field investigation are samewith in18kiwifruit germplasm materiales, and were significantce level. Therefore, theresistance identification method in vitro and potted branches could be used to identifykiwifruit canker, but compared with potted plant inoculation, in vitro inoculation was more simple and easy to operate.3. The PAL, SOD, POD and PPO activity of ‘Maohua’,‘Jinkui’,‘Huayou’‘Red sun’and‘Jinyang’potted kiwifruit branches after5,10,15,20d inoculation were significantlyincreased (P <0.05)than0d inoculation, but the additions of enzyme activity and enzymeactivity peak time is different in five kinds of kiwifruit germplasm resources. The PAL,SOD,POD and PPO activity of ‘Maohua’,‘Jinkui’ and ‘Huayou’ after inoculation continued to riserapidly, the activity height occured after10d inoculation and then increased more slowly.However, the PAL, SOD, POD and PPO activity of ‘Red sun’and ‘Jinyang’ rised to peak after15d inoculation, and the peaks were lower than ‘Maohua’,‘Jinkui’ and ‘Huayou’. These fourkinds of enzymes activity were in slow decline after the peak. But something was not samefor CAT. The CAT activity ‘Maohua’,‘Jinkui’ and ‘Huayou’ were significantly increased (P <0.05) than0d inoculation but the activity height of ‘Red sun’and ‘Jinyang’ did not occurred.The CAT activity height of ‘Jinkui’ occured after5d inoculation, the activity height of‘Maohua’ and ‘Huayou’ after10d inoculation. The results showed that the activity of PAL,CAT, POD, CAT, and PPO were related to the kiwifruit canker resistant.4. A total of51primer pairs were screened, and an SSR marker(UDK97-428116) closelylinked to resistance gene was identified. The validity of this SSR marker was verified by40kinds of kiwifruit germplasm in vitro inoculation. The SSR marker UDK97-428116can beused as molecular marker assisted selection in disease resistance to kiwifruit canker. |
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