Pathogens Diagnosis Affecting Garlic Sprouts In Logistics Quality And Safety And Pathogenicity Studies

Garlic sprout is the scape of the Allium sativum L. and one of the year-round supply vegetables, which has the largest storage in low temperature and the longest storage period. There is a very serious problem about the quality of garlic sprouts in the logistics and transport. Market researches about garlic sprouts diseases in Shanghai were conducted to identify the major pathogen and the pathogenic epidemiology, which can provide strategies to control these market diseases effectively. The results showed that:1、From January2011to October2012, we investigated the whole markets, super markets and retail stores selling vegetables in Shanghai, the results showed that:the main source of the garlic sprouts sold in Shanghai is from Cangshan and Jinxiang in Shandong province. The sales volume and price of garlic sprouts were different in different seasons. And the lowest saling price in May is3.2yuan/kg, the correspongding sale is up to25,000kg; the highest in January is9.6yuan/kg, but the sales became lowest about5,000kg. The reasons causeing loss during logistics of garlic sprouts in marlets’can be summarized as following:one is the improper temperature during saling in the markets; the other is post-harvest disease causing pathogenic fungi. And the latter is the main reasons causing loss.2、Isolation and identification of pathogens were conducted.287pathogenic fungi were isolated from the bottom of the garlic sprouts, stems and bracts. Based on colony morphology and spore morphology, these fungi were identified as Penicillium, Botrytis, Colletotrichum, Fusarium, etc. Among these fungi, Colletotrichum account for the highest rate. EXGL-19showed the strongest pathogenicity. This fungus was identified as Botrytis squamosa by ITS sequencing. B. squamosa as the main pathogens of markets diseases of garlic sprouts was reported for the first time.3、The biological characteristics of the major pathogen were researched. The results shows that, the mycelia can grow at the temperature range from0℃to30℃, while the optimum growth temperature is from15℃to20℃; it could grow at pH value ranged from2to9, with the optimum pH was5. There were two types spore, macroconidium produced at0℃cultured on PDA for60days; the other was microconidia produced at20℃cultured on PDA for16days, this feature indicates a potential threat to the garlic sprouts in storage.4、Ethylene is the plant hormone usually causing senescence. The bracts of diseased garlic sprouts in markets turned yellowed and decayed easier than stems. Our results showed that the amount of ethylene production of bract was more than the other parts irrespective of pathogen infection; B. squamosa infection promoted ethylene emission and senescence of garlic sprouts.5、RAPD assays and SCAR were used to develop molecular markers and to design specific primers to identify EXGL-19from other fungi. We screen8primers from57, and OPB18were chosed to design a pair of primers B.sq-301which could specifically discriminate B. squamosa from other38fungi.This study overview the symptoms and causes of loss of garlic sprouts during market period, the biological characteristics of the main pathogen were studied. We also develop the molecular markers of B. squamosa using RAPD-SCAR to identify this fungus quickly. All those were done in order to control the market diseases of garlic sprouts effectively, and to reduce the economic losses.