Stepwise evaluation and selection of hybrid potato material for disease resistance at the early stages of breeding

Abstract

Purpose. To substantiate a scientific and methodologicalapproach to the stepwise evaluation and selection of hybridpotato material for disease resistance at the early stages ofthe breeding process, with differentiation of breeding decisioncriteria according to genotype representation, the reliabilityof the obtained evaluation, and the possibility of confirmingthe response in subsequent clonal generations.Methods. The scientific and methodological approachwas developed through a comparative analysis of the possibilitiesfor phytopathological evaluation of hybrid materialat successive stages of the breeding process. For the seedling,single-tuber, and subsequent clonal generations, genotyperepresentation, available objects of evaluation, thepossibility of repeated confirmation of genotype response,and the risk of an erroneous breeding decision were compared.Scientific publications on potato breeding, phytopathology,and the genetics of resistance were used to providethe theoretical basis for the criteria and limitations of theproposed system.Results. The relationship between the stringency ofbreeding decisions, genotype representation, and the reliabilityof information on disease response was substantiated.For seedlings represented by a single plant and a limitednumber of tubers, moderate negative selection with the eliminationof forms showing clearly expressed undesirable traitswas considered appropriate. In the single-tuber generation,a comprehensive evaluation combining assessment of foliardiseases and virus-like symptoms with post-harvest examinationof tubers from individual plants was proposed, while theresponse of a single plant should be regarded as preliminary.As genotype representation increases in subsequent clonalgenerations, the possibility of confirming the reproducibilityof its response also increases, providing a basis for transitionfrom cautious negative selection to confirmatory and positiveselection. This process is proposed to be consideredas the sequential accumulation of information, in which thestringency of breeding decisions increases together with thestrength of the supporting evidence. The “cost of selectionerror” was introduced as a methodological component of theapproach, reflecting the unequal consequences of erroneouselimination of a promising genotype and temporary retentionof a susceptible form for subsequent evaluation. Conclusions. The proposed scientific and methodologicalapproach provides for aligning selection criteria anddecision stringency with the amount and reliability of informationavailable at a particular stage of the breeding process.When genotype representation is limited, moderate negativeselection should be preferred, whereas clonal propagationand repeated evaluation in different growing years provide abasis for confirming the reproducibility of genotype responseand strengthening positive selection. Consideration of the“cost of selection error” makes it possible to differentiatebreeding decisions and reduce the risk of irreversible loss ofpotentially valuable material at the early stages of breeding.