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Characterization of a Late Blight Resistance Gene Homologous to R2 in Potato Variety Payette Russet
American Journal of Potato Research ( IF 1.5 ) Pub Date : 2021-01-05 , DOI: 10.1007/s12230-020-09811-2
Hari S. Karki , Dennis A. Halterman , Jeffrey B. Endelman

Breeding for late blight resistance has traditionally relied on phenotypic selection, but as the number of characterized resistance (R) genes has grown, so have the possibilities for genotypic selection. One challenge for breeding russet varieties is the lack of information about the genetic basis of resistance in this germplasm group. Based on observations of strong resistance by ‘Payette Russet’ to genotype US-23 of the late blight pathogen Phytophthora infestans in inoculated experiments, we deduced the variety must contain at least one major R gene. To identify the gene(s), 79 F1 progeny were screened using a detached leaf assay and classified resistant vs. susceptible. Linkage mapping using markers from the potato SNP array revealed a single resistant haplotype on the short arm of chromosome group 4, which coincides with the R2/Rpi-abpt/Rpi-blb3 locus. PCR amplification and sequencing of the gene in Payette revealed it is homologous to R2, and transient expression experiments in Nicotiana benthamiana confirmed its recognition of the Avr2 effector. Sequencing of a small diversity panel revealed a SNP unique to resistant haplotypes at the R2 locus, which was converted to a KASP marker that showed perfect prediction accuracy in the F1 population and diversity panel. Although many genotypes of P. infestans are virulent against R2, even when defeated this gene may be valuable as one component of a multi-genic approach to quantitative resistance.



中文翻译:

马铃薯品种Payette Russet中与R2同源的晚疫病抗性基因的表征

传统上,晚疫病抗性育种依靠表型选择,但是随着特征性抗性(R)基因数量的增加,基因型选择的可能性也随之增加。繁殖赤褐色品种的挑战之一是缺乏有关该种质组抗性遗传基础的信息。基于“ Payette Russet”对晚疫病病原菌疫霉疫霉US-23基因型的强抗性观察在接种实验中,我们推论该品种必须包含至少一个主要的R基因。为了鉴定基因,使用离体叶片测定法筛选了79个F1后代,并将其归类为易感抗性。使用来自马铃薯SNP阵列的标记的连锁作图揭示了第4号染色体短臂上的单一抗性单倍型,其与R2 / Rpi-abpt / Rpi-blb3基因座一致。在Payette中对该基因进行PCR扩增和测序后发现,该基因与R2同源,在本氏烟草中的瞬时表达实验证实了其对Avr2效应子的识别。小型多样性小组的测序揭示了R2的抗性单倍型所特有的SNP位点,该位点被转换为KASP标记,在F1种群和多样性面板中显示出完美的预测准确性。尽管许多致病疫霉的基因型对R2具有毒力,但即使被打败,该基因也可能作为定量抗性多基因方法的一个组成部分而有价值。

更新日期:2021-01-05
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