Reena Sharma

Molecular characterization of potato virus Y resistance in potato (Solanum tuberosum L.)

Amongst viruses, Potato virus Y (PVY) is the most prevalent virus affecting potato productivity. Resistance genes (Ry) in Solanum tuberosum subsp. andigena (Ryadg) and Solanum stoloniferum (Rysto) confer extreme resistance (ER) to PVY. SCAR marker RYSC3 for Ryadg gene and SSR marker STM0003 for Rysto gene were used to screen 119 potato genotypes including 44 Indian varieties. These genotypes were also challenge inoculated with PVYo strain and confirmed for ER by DAS-ELISA. Gene Ryadg was present in 11 and Rysto in 22 genotypes, while 3 genotypes possessed both the genes. The statistical analysis indicated that among the two tested markers, RYSC3 is better diagnostic of PVY resistance. The identified genotypes can serve as potential source for future virus resistance breeding programs.

Validation of potato cyst nematode resistant genotypes through molecular markers

Forty-two potato genotypes exhibiting phenotypic resistance against Potato Cyst Nematode (PCN) species Globodera rostochiensis (golden) and Globodera pallida (white) were screened for molecular validation using tightly linked genetic DNA markers. H1 and GroV1 gene conferring resistance against golden nematodes were validated by TG 689 & 57R and X02 markers, respectively. Similarly, resistance against Globodera pallida governed by QTL GpaVvrn and QTLs Gpa5, Gpa6, was confirmed by corresponding markers HC and SPUD1636. On the basis of phenotypic and genotypic confirmation, this study identifies CP 1843, 1879 and JEX/A 267 as elite potato genotypes that can be utilized as parental lines for introgression of resistant genes against both PCN species.

Effect of Elevated Temperature on In Vitro Microtuberization of Potato Genotypes with Different Thermotolerance Levels

Effect of Elevated Temperature on In Vitro Microtuberization of Potato Genotypes with Different Thermotolerance Levels Extension of potato cultivation to tropical areas has been constrained by the thermosensitivity of most cultivars which require low temperature during induction of tuber formation and their subsequent development. Development of culivars for heat tolerance requires robust phenotyping methods for evaluating germplasm which is generally maintained as in vitro plant cultures. Microtuber production behaviour of five potato genotypes with contrasting themotolerance levels was studied to develop an in vitro assay system for screening potato genotypes for tolerance to high temperatures. Significant differences were observed with respect to tuber number, tuber weight and plant weight in all the genotypes at ambient (18°C) and elevated temperature (25°C). Kufri Himalini and CP4054 produced highest tuber number at 18°C and 24°C respectively. Although plant weight increased with an increase in temperature in all genotypes, total biomass increased only in tolerant genotypes. Heat tolerant genotypes exhibited comparable tuberization at both the temperatures whereas tuber formation was reduced in heat sensitive genotypes at elevated temperature. All genotypes formed micro tubers in vitro but only thermotolerant genotypes formed tubers in soil at elevated temperature, suggesting that mixotropic culture media overcome the effect of high temperature in the inhibition of tuberization indicating the need to use culture media devoid of hormones for developing a reliable in vitro assay system.