Molecular Detection Of Pathogens Of Alfalfa Root Diseases In North-Xinjiang

Alfalfa is the most important planting forage grass in Xinjiang, Alfalfa root rot is one of the main diseases in Alfalfa production, Alfalfa verticillium wilt is a potential threat for the Alfalfa production. This study adopts the specific primer PCR detection technology to inspect the mixed diseased sample located in the main Alfalfa planting regions of north Xinjiang and the diseased sample collected per single plant in the single serious illness field, as well as the regularly collected diseased sample of multiple root rot germs after the mixed inoculation respectively. In order to define the root rot pathogenic species of development zones in northern region of Xinjiang, various pathogenic fungus infection dynamics on Alfalfa and to lay the foundation of research on the root rot pathogens compound infection regular and control technique; meanwhile, carry out PCR detection to the extensively collected diseased samples to verify Alfalfa verticillium wilt in the development region of northern Xinjiang; Provide the basis for the effective prevention and control of the disease.The specificity lead PCR detection of mixed diseased samples of Alfalfa root and basal stem shows that: there are 3species of Fusarium in diseased samples(Fusarium equiseti, Fusarium acuminatum and Fusarium oxysporum), and 1species of Rhizoctonia(Rhizoctonia Solani); only 3 species of Fusarium(Fusarium.acuminatum, Fusarium.solani and Fusarium oxysporum) are detected from stem base diseased samples; which give the fact that there are 4 main Fusarium species(F. equiseti, F. acuminatum, F. solani and F. oxysporum) and 1 Rhizoctonia species(R. Solani) of root rot pathogenic species in the main Alfalfa planting regions of north Xinjiang and there is a slight different between the root and basal stem area(R. solani and F. equiseti only detected in the root diseased samples, and F. solani only detected in the basal stem diseased samples).The specificity lead PCR detection of 15 root disease samples collected per single plant in the single serious illness field and 15 basal stem disease samples shows :there are six same pathogen species detected from the root disease samples of root rot serious illness field and the basal stem disease samples, one more species(F.sporotrichoides) than the total pathogen species of extensively collected mixed disease samples, namely 5 Fusarium species and 1 R. Solani are detected except F. avenaceum; Thus again verified and supplemented the alfalfa root rot pathogen species of mixed disease samples.There is an obvious difference of strain rate for each pathogenic fungi in 30 diseased samples, among which, 5species of pathogens(R. solani, F. equiseti, F. acuminatum, F. solani. and F. oxysporum) have a higher detection rate(47%~73%) in the root disease samples and basal stem disease samples. It again indicates that these 5 pathogen species are ubiquitously existed in the Alfalfa root rot diseased plant and are the main pathogenic fungi of Alfalfa root rot,among which, F. solani and F. oxysporum have a higher detection rate(over 60%) in the 30 diseased samples and they are the dominant pathogenic species of Alfalfa root rot; F. sporotrichoides has a lower detection rate(20%~33%) and the detection rate of F. avenaceum is 0% which shows these two pathogenic species have a little or minute quantity infection in the field diseased plants and they are the vulnerable species among 7 pathogenic species.In addition, through the comparison of the detection results of root diseased samples and basal stem diseased samples, it can be seen that the dominant pathogenic species are different between the root diseased samples and basal stem diseased samples. In root diseased samples, F. oxysporum, F. acuminatum and R. solani are the dominant species and in basal stem diseased samples, F. solani and F. equiseti are the dominant species.And the pathogenic species detected from the single plant diseased samples, no matter in the root diseased samples or the basal stem diseased samples, the mixed infection of a single plant by two or above pathogen species is a common case.The detection results of artificial inoculation diseased plant samples again give the fact that the above 5 pathogenic species ubiquitously exist in the diseased plant of Alfalfa root rot and are the main pathogenic fungus of the Alfalfa root rot, among which, F. solani and F. oxysporum have the highest detection rate in diseased samples and are the dominant pathogen species of alfalfa root rot; F. avenaceum has the lowest detection rate, to know the detection rate of F. sporotrichoides is 0%, which shows these two pathogenic species have a little or minute quantity infection in the field diseased plants and they are the vulnerable species among 7 pathogenic species.Verticillium dahliae and Verticillium albo-atrum were not detected from the field samples collected the nort of Xinjiang, including Changji,Hutubi,Sanping farm,Wuyi farm and Ining. The result indicates the epidemic situation of Verticillium wilt does not exist at this region temporarily.