A Methodological Approach for Evaluating the Genotypic Variation for Physiological Adaptation of Potato Wild Relatives for Heat Tolerance Breeding

TL;DR

This paper introduces a method to evaluate heat tolerance in wild potato relatives using genetic variation and physiological traits to support breeding for climate resilience.

Contribution

A novel methodological approach using PCA and HTC to assess and classify heat tolerance in wild potato genotypes for breeding purposes.

Findings

Significant variation in gas exchange and chlorophyll fluorescence indicates strong breeding potential under heat stress.

S. chacoense outperforms S. commersonii in tuber production and gas exchange under heat stress.

PCA-derived weights and clustering categorize genotypes into heat tolerance groups for targeted breeding.

Abstract

Wild potato relatives are vital for breeding programs to tackle rising temperatures. This study proposes a methodological approach based on the examination of genetic variation among 19 accessions belonging to Solanum chacoense and Solanum commersonii from the Embrapa Potato Genebank under heat stress (HS). Heat tolerance coefficient (HTC) was calculated using genotypic values predicted through mixed models. After 15 days of heat stress (DHS), a significant variation in gas exchange and chlorophyll fluorescence indicates strong breeding potential and photosystem resilience. By 35 DHS, increased pigment variation suggests acclimation. Based on predicted genotypic values, S. chacoense outperforms S. commersonii in tuber production and gas exchange under HS, and principal component analysis (PCA) performed using the HTC shows early resistance driven by photosynthesis, mid-term by tuber yield, and long-term by gas exchange and tuber production. Genotypes BRA00167017-3, BRA00167023-1, BRA00167025-6, and BRA00167028-0 excel in heat comprehensive evaluation values (HCEVs)/comprehensive principal component value (F) rankings, demonstrating robust photosynthesis, thermoregulation, and tuber yield. Cluster analysis identifies these as highly tolerant, ideal for breeding heat-resilient potatoes. These PCA-derived weights and genotype clustering system provide a precise tool for selecting heat-tolerant wild potato germplasm, categorizing them into highly tolerant, moderately tolerant, sensitive with late recovery, and highly sensitive groups acquired for specific objectives of the breeding programs to climate change.

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