Generation of frost tolerant potato (Solanum tuberosum L.) clones through intervarietal hybridization and expression analysis of putative frost tolerance genes
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Date
2022
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Punjab Agricultural University, Ludhiana
Abstract
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.
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Angmo, Dechen (2022). Generation of frost tolerant potato (Solanum tuberosum L.) clones through intervarietal hybridization and expression analysis of putative frost tolerance genes (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.