Heritable Variation, Genetic and Phenotypic Correlations for Tuber Traits and Host Plant Resistance to Late Blight for Potato Breeding in Scandinavian Testing Sites

Rodomiro Ortiz,Fredrik Reslow,José Crossa,Jaime Cuevas

doi:10.3390/agriculture11121287

Abstract

Potato breeding aims to improve crop productivity, quality and resilience based on heritable characteristics. Estimating the trait heritability and correlations—both genetic and phenotypic—among characteristics in a target population of environments allows us to define the best breeding method that leads to selection gains. Breeding clones (47) and released cultivars (209) were grown using simple lattice designs at three testing sites in northern and southern Sweden to estimate the best linear unbiased predictors (BLUPs) derived from mixed linear models for characteristics such as tuber weight (total and according to sizes), host plant resistance to late blight (caused by the oomycete Phytophthora infestans) and tuber quality (starch percentage based on specific gravity measurements and reducing sugars). There was significant heritable variation for all the characteristics investigated. Tuber starch percentage and total tuber weight were the traits with the highest broad-sense heritability (H2), while the weight for the smallest size (<40 mm) had the highest H2 among the different tuber categories. These results show the potential for further improving these traits for Scandinavia through recombination and selection in segregating offspring. The genetic and phenotypic correlations among the tuber weight characteristics were significant (p ≤ 0.05) irrespective of their sizes, but none were significant (p > 0.05) with tuber starch percentage. Host plant resistance to late blight was negatively and significantly associated with tuber weight and starch percentage, thereby showing the strong effects of this disease on the productivity and quality of the potatoes.

Highlights

Introduction published maps and institutional affilPotato (Solanum tuberosum L.) remains among the three most important crops directly feeding the global human population [1]
Tuber starch percentage and total tuber yield had the lowest coefficient of variation across the trial sites (6.04 and 17.94%, respectively), while the coefficient of variation was high for tuber weight by grading sizes
There were highly significant differences among the best linear unbiased predictors (BLUPs) of breeding clones and released cultivars for all the traits (Supplementary Table S2) across and within the sites. These results clearly show the great heritable variation for traits evaluated, tuber starch percentage and total tuber weight, and potential for further improving these through selection and recombination

Summary

Introduction

Potato (Solanum tuberosum L.) remains among the three most important crops directly feeding the global human population [1]. This tetraploid polysomic crop (2n = 4x = 48 chromosomes), faces various challenges, e.g., its vulnerability to various pests such as late blight caused by the oomycete Phytophthora infestans (Mont.) de Bary, which is the most important threat to potato production worldwide [2]. P. infestans rapidly destroys a potato crop due to its elevated virulence. This pathogen infects the entire plant, including the stems, leaves and tubers, leading to significant global tuber yield loss that translates into several USD billion annually. The traits determining such characteristics may not always show positive associations, and the useful genetic variation available for iations

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Methods

Results