Genetic Basis of Potato Tuber Defects and Identification of Heat-Tolerant Clones

Abstract

Heat stress during the potato growing season reduces tuber marketable yield and quality. Tuber quality deterioration includes external (heat sprouts, chained tubers, knobs) and internal (vascular discoloration, hollow heart, internal heat necrosis) tuber defects, as well as a reduction in their specific gravity and increases in reducing sugars that result in suboptimal (darker) processed products (french fries and chips). Successfully cultivating potatoes under heat-stress conditions requires planting heat-tolerant varieties that can produce high yields of marketable tubers, few external and internal tuber defects, high specific gravity, and low reducing sugars (in the case of processing potatoes). Heat tolerance is a complex trait, and understanding its genetic basis will aid in developing heat-tolerant potato varieties. A panel of 217 diverse potato clones was evaluated for yield and quality attributes in Dalhart (2019 and 2020) and Springlake (2020 and 2021), Texas, and genotyped with the Infinium 22 K V3 Potato Array. A genome-wide association study was performed to identify genomic regions associated with heat-tolerance traits using the GWASpoly package. Quantitative trait loci were identified on chromosomes 1, 3, 4, 6, 8, and 11 for external defects and on chromosomes 1, 2, 3, 10, and 11 for internal defects. Yield-related quantitative trait loci were detected on chromosomes 1, 6, and 10 pertaining to the average tuber weight and tuber number per plant. Genomic-estimated breeding values were calculated using the StageWise package. Clones with low genomic-estimated breeding values for tuber defects were identified as donors of good traits to improve heat tolerance. The identified genomic regions associated with heat-tolerance attributes and the genomic-estimated breeding values will be helpful to develop new potato cultivars with enhanced heat tolerance in potatoes.

Assessing heat tolerance in potatoes: Responses to stressful Texas field locations and controlled contrasting greenhouse conditions

“…Springlake and Dalhart experienced high temperatures throughout the crop season ( Table 2 ). In Springlake, temperatures steadily rose until harvest, while in Dalhart, temperatures peaked 60-70 days after planting and gradually declined ( Gautam et al., 2024 ). Photoperiod followed a similar trend: in Dalhart, day length peaked at 50-60 days (14 hours 36 minutes) then sharply decreased to 12 hours, while in Springlake, it reached 14 hours 24 minutes near harvest ( Supplementary Figure 1 ).…”

“…In Lavras, Brazil, the mean maximum and minimum temperatures are 28.5 and 16.5°C, respectively ( Lambert et al., 2006 ). Both the locations in our study encounter prolonged periods of temperature exceeding 25°C throughout the crop period and often reaching above 40°C ( Gautam et al., 2024 ). High temperatures inhibit potato tuber growth and development in short- and long-day conditions ( Wheeler and Tibbitts, 1986 ), with the inhibitory effect more significant in long-day conditions ( Van Dam et al., 1996 ; Jackson, 1999 ) as in our study.…”

“…For the experiments related to objective 1, temperature data was retrieved from NOAA ( https://www.ncdc.noaa.gov/cdo-web/ , accessed on December 12, 2022) for both Texas locations, including maximum and minimum temperatures/day during the crop period. The temperature conditions at each location are summarized in Table 2 and discussed in our previous work ( Gautam et al., 2024 ). For objectives 2 and 3 trials, the temperatures were monitored using the EL-USB-1 temperature loggers (Dataq Instruments Inc., Ohio, USA).…”