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20221
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Subject: Vegetable Science × Author: Angmo, Dechen × Start date: 1978 ×
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    Generation of frost tolerant potato (Solanum tuberosum L.) clones through intervarietal hybridization and expression analysis of putative frost tolerance genes
    (Punjab Agricultural University, Ludhiana, 2022) Angmo, Dechen; Sharma, Sat Pal
    The present study was carried out with an overall aim to generate frost tolerant potato clones and optimization of phenotyping techniques in order to complement the natural field selection criteria. The physiological responses to low temperature stress were explored using four potato genotypes viz. Kufri Anand, J-2/19, MS/7-645 and Kufri Pukhraj under in vitro controlled conditions. Significant variation was observed amongst genotypes for parameters associated with frost tolerance in potato such as cell membrane stability, activity of PSII, photosynthetic efficiency and leaf morpho-anatomical traits. The genotypes J/2-19 and Kufri Anand exhibited higher PN, gs and ΔF/Fm’values and lower electrolyte leakage as compared to the sensitive genotype Kufri Pukhraj upon cold acclimation and during recovery days after freezing exposure. Similarly, J-2/19 genotype also recorded higher adaxial trichome density than the sensitive genotype MS/7-645. In order to identify the fold changes in the expression of three candidate genes involved in cold stress responses in potato viz. dehydrin, hsp70 and SAD a qRT-PCR study was also performed. Overall an increase in gene expression was observed in cold acclimated plants of all the genotypes compared to non-acclimated plants. However, the increase was more pronounced in tolerant genotype (J-2/19) as compared with susceptible genotypes (MS/7-645 and Kufri Pukhraj). In the summer 2018, the segregating progenies were developed through hybridization among contrasting parents viz. J-2/19  MS/7-645 (PAU3), MS/7-645  J-2/19(PAU7) and MS/7-645  CP-3765 (PAU9) at Keylong, HP. In F1C1 and F1C2 generations, the characterization of the generated potato clones was accomplished on the basis of leaf morpho-anatomical traits and electrolyte leakage assay. To determine the association between the key traits and potential frost tolerant potato clones, various statistical approaches, such as cluster analysis, principal component analysis and genotype by trait biplot analysis were performed. Total 11, 10 and 8 clones from PAU3, PAU7 and PAU9 crosses, respectively were identified exhibiting potential frost tolerant characteristics with desirable horticultural traits for their further evaluation. Thus, the findings of this study concluded that in addition to electrolyte leakage the chlorophyll fluorescence and leaf gas exchange parameters can be effectively utilized for screening frost tolerant potato genotypes, but with certain limitations. Furthermore, the leaf morpho-anatomical traits have been confirmed to be associated with frost tolerance through decrease in foliage damage and electrolyte leakage. Therefore, these traits can potentially be used for screening of large segregating populations for freezing tolerance in the early clonal generations in potato.