Engineering heat tolerance in potato by temperature‐dependent expression of a specific allele of HEAT‐SHOCK COGNATE 70

Abstract

SummaryFor many commercial potato cultivars, tuber yield is optimal at average daytime temperatures in the range of 14–22 °C. Further rises in ambient temperature can reduce or completely inhibit potato tuber production, with damaging consequences for both producer and consumer. The aim of this study was to use a genetic screen based on a model tuberization assay to identify quantitative trait loci (QTL) associated with enhanced tuber yield. A candidate gene encoding HSc70 was identified within one of the three QTL intervals associated with elevated yield in a Phureja–Tuberosum hybrid diploid potato population (06H1). A particular HSc70 allelic variant was linked to elevated yield in the 06H1 progeny. Expression of this allelic variant was much higher than other alleles, particularly on exposure to moderately elevated temperature. Transient expression of this allele in Nicotiana benthamiana resulted in significantly enhanced tolerance to elevated temperature. An TA repeat element was present in the promoter of this allele, but not in other HSc70 alleles identified in the population. Expression of the HSc70 allelic variant under its native promoter in the potato cultivar Desiree resulted in enhanced HSc70 expression at elevated temperature. This was reflected in greater tolerance to heat stress as determined by improved yield under moderately elevated temperature in a model nodal cutting tuberization system and in plants grown from stem cuttings. Our results identify HSc70 expression level as a significant factor influencing yield stability under moderately elevated temperature and identify specific allelic variants of HSc70 for the induction of thermotolerance via conventional introgression or molecular breeding approaches.

Interactive Responses of Potato (Solanum tuberosum L.) Plants to Heat Stress and Infection With Potato Virus Y

“…To confirm these observations and provide quantitative evaluation of the thermotolerance, we determined how the cell membrane integrity changes in these cultivars in response to temperatures by measuring leakage of electrolytes ( Ahn et al, 2004 ; Savić et al, 2012 ; Trapero-Mozos et al, 2018 ). In this work, potato leaf disks were subjected to high (47°C) and normal (22°C; control) temperatures for 5 h, and electrolyte leakage was calculated by measuring the percentage of difference in conductivity between the samples at 47 and 22°C.…”

“…To assess thermotolerance by measuring cell membrane injury, an electrolyte leakage assay was carried out, essentially as described in Trapero-Mozos et al (2018) . Four 10-mm leaf disks each from a different leaf per plant were placed in test tubes containing 5 mL of distilled water.…”

Physiological, Biochemical, and Transcriptional Responses to Single and Combined Abiotic Stress in Stress-Tolerant and Stress-Sensitive Potato Genotypes

“…Samples were stored at −80°C prior to lyophilization, extraction, and analysis. Samples were extracted as polar and non-polar phases, derivatized, and analyzed by gas chromatography mass spectrometry (GC-MS) as previously described (Dobson et al, 2008;Trapero-Mozos et al, 2018b). Metabolite profiles were acquired using a GC-MS (DSQII Thermo-Finnigan, UK) system carried on a DB5-MSTM column (15 m × 0.25 mm × 0.25 μm; J&W, Folsom, CA, USA) as described by Foito et al (2013).…”

A reversible light- and genotype-dependent acquired thermotolerance response protects the potato plant from damage due to excessive temperature

“…Very similar patterns of gene expression were observed using both techniques (Online Resource S12). The selected HSPs, used as test genes, were those previously implicated in acclimation processes (HSP17.6 and HSP101; McLoughlin et al 2016 ) and a potato HSC70 gene recently demonstrated to protect against elevated temperature in potato (Trapero-Mozos et al 2017 ).…”

“…Potato elongation factor1-alpha (EF1α) primers were used as a control. Quantitative PCR was performed as previously described (Trapero-Mozos et al 2017 ).…”