| Late blight caused by Phytophthora infestans is one of the most serious diseases in potato production.Heilongjiang province is an important production base for both commercial potatoes and seed potatoes in China.Due to frequent occurrence of late blight,the potato yield and quality in Heilongjiang province are significantly reduced,which seriously restricts the development of commercial potato and seed potato industry in Heilongjiang province.In this research,mating type,metalaxyl sensitivity,physiological races and SSR genotyping were determined for 124 isolates collected from Heilongjiang province during 2012-2015,and tuber late blight resistance of 13 advanced generation potato clones was identified by inoculation of potato slices with five isolates selected from physiological races tested.These results could provide a theoretical support for integrated prevention and control of potato late blight and tuber late blight resistant breeding in Heilongjiang province.The results are as follows.1.Sixty-two isolates were A1 mating type(accounting for 50%),and 62 isolates were A2 mating type(accounding for 50%).No self-fertile isolates were found.The proportion of A2 mating type isolates decreased with year.All isolates were A2 mating type in Heihe and no A2 mating type isolate was found in Jiamusi.Both A1 and A2 mating type isolates were found in Qiqihar,Harbin and Suihua,and the A2 mating type isolates was the dominant isolate in Qiqihar.2.Metalaxyl sensitive,intermediate resistant and high resistant isolates accounted for 20.97%,15.32% and 63.71%,respectively.The proportion of high resistant and intermediate isolates was obviously higher than that of sensitive ones,which rose first and then dropped.Among all the isolates,a greater proportion of the A2 mating type isolates were resistant,accounting for 96.77%.In most regions of Heilongjiang province,the resistant isolates accounted for a large proportion(more than 70%),indicating that the Phytophthora infestans on potatoes in Heilongjiang was resistant to metalaxyl.3.Forty-seven physiological races were identified.The dominant race was 1.2.3.4.5.6.7.8.9.10.11,accounting for 15.74%.From the year 2012 to 2015,the complexity of the physiological races of isolates collected from Heilongjiang province rose first and then dropped.The complexity in 2013 was the highest.The complexity of virulence genes decreased firstly,then increased and then decreased,and the virulence genes in 2014 were the most complex.4.Forty-seven genotypes were detected,31 of which were rare genotypes,and no genotype was identified the same as reference genotype 13-A2(3928A).The same genotypic isolates had the same mating type but metalaxyl sensitivity and physiological race were not.Among the five regions,the genotypes of Harbin were the most complicated.During the four years,the genetic complexity of the isolates increased with year,with the complexity being the highest in 2015.A total of 62 loci were detected with an average of 5.2 loci per marker,and the average polymorphism information content was 0.5204.The polymorphism of primer D13 was the highest which amplified 20 different loci.The genetic similarity coefficient between the isolates in the population was 0.6271-1,and the cluster analysis showed that the isolate clustering was not related to the year and the geographical origin.5.One high tuber resistant advanced generation clone(H17-54374),and two medium resistant clones(H17-44056,H17-54280)were identified,and the remaining ten clones showed susceptibility or high susceptibility to late blight.Among the 5 isolates tested,the virulence of the "super virulent races" was higher than that of the other isolates. |
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