Analysis of Population Genetic Change to Single Oospore Strains of Phytophthora infestans

The occurrence of sexual reproduction accelerates the population genetic variation of Phytophthora infestans and makes it more difficult to control.The systematic analysis of the differentiation of phenotype(mating type and metalaxyl sensitivity)and genotype(mtDNA haplotype and SSR genotype)of 65 single oospore strains of P.infestans was carried out in this article.Five test strains were isolated from Heilongjiang Province and Mongolia Autonomous Region.The experiment results showed that the isolation ratio of metalaxyl resistance(MR:HR)of single oospore strains produced through the cross of medium resistance and high resistant parents was 18:13;the isolation ratio of the metalaxyl resistance(S:MR:HR)of single oospore strains produced through the cross of sensitive and high resistant parents was 4:12:7.The progenies of single oospore strains produced through self-fertility parents with medium resistance were all of the medium resistance.The mating types A1:A2 was greater than 1:1 in single oospore strains of the progenies,which did not conform to the Mendel's law of inheritance.All single oospore strains of the progenies inherited mitochondrial DNA fragments from only one parent.Sexual recombination of single oospore strains was verified by using two pairs of SSR primers(Pi4B and Pi4G).At the locus of Pi4B and Pi4G in the cross of KS-37 and KS-25,the separation frequencies of allele were 19:12 and 14:17,respectively.They produced two new genotype strains.This study could provide a basis for formulating disease control strategies.

Life and death:the destiny of Phytophthora sojae determined by a receptor-like kinase

Leucine-rich repeat receptor-like kinases(LRR-RLKs)are well known to act in plant growth,development,and defense responses.Plant LRR-RLKs locate on cell surface to sense and initiate responsive signals to a variety of extracellular stimuli,such as microbe-associated molecular patterns(MAMPs)released from microorganisms.LRR-RLKs are also present in microbes and function in microbial growth and development,but their roles in communicating with hosts are largely unknown.A recent study published in Nature Communications uncovered that a microbial LRR-RLK,PsRLK6,is required for oospore development in the sexual reproduction of Phytophthora sojae,an oomycete pathogen that causes root and stem rot in soybean.Meanwhile,PsRLK6 is recognized as a novel type of MAMP by an unknown plant LRR receptor-like protein and triggers immune responses in soybean,tomato,and Nicotiana benthamiana.The findings reveal dual roles of a pathogen LRR-RLK in determining both life through sexual reproduction and death through triggering plant immunity.