Marker Based Screening of F1 (Firdous x Gala) Mapping Population for Major Scab Resistance Gene Rvi6 in Apple (Malus × Domestica)

Abstract

Scab caused by Venturia inaequalis (Cke.) Wint. is the most important fungal disease of apple. The development and deployment of genetic resistance is reliable and a safe option to combat the dreaded disease with palpable advantage as compared to chemical control. A variety Firdous developed by SKUAST-K has been known for its resistance, however, genetic basis of resistance has not been proved or established till date. An initiative was taken to cross the scab resistant variety, Firdous to susceptible cultivar Gala that resulted into population of 110F 1 plants. Among these derived F 1 s 46 were tested for presence of Vf gene using the linked SCAR marker. The marker analysis helped us to identify resistance specific alleles for gene Rvi6 in 25 out of 46 F 1 s. The F 1 population was also screened using a mono-conidial mixture of four races viz., (0), (1), (2) and (1, 2) under controlled conditions. A fair degree of correlation existed between allelic information and reaction phenotype that indicated the presence of Rvi6 in Firdous. Further, the F 1 population was screened for the markers linked to fruit firmness. The combined information of both the markers may help us to identify individuals which are resistant to scab and carry favourable alleles for fruit firmness required for better storage and quality.

Marker Based Screening of F1 (Rosalie x Fuji) Mapping Population for Major Scab Resistance Gene Rvi6 in Apple (Malus × Domestica)

“…The F1s were tested for presence of Rvi6 gene using the linked SCAR markerAL-07 (F: 5`-TGGAAGAGAGATCCAGAAAGTG-3'; R: 5'-CATCCCTCCACAAATGCC-3). PCR assay was performed in a reaction volume of 20µL containing 25-50 ng genomic DNA, 1x PCR buffer (20 mMTris-Cl pH 8.4, 50mM KCl), 1.5 mM MgCl2, 0.2 mM dNTPs and 1.0 unit of Taq DNA polymerase" [14]. "PCR amplifications were performed in a gradient thermal cycler (Make TAKARA, Japan) with the following thermal regimes: Initial denaturation at 94°C for 5 min was followed by 35 cycles at 94°C for 1 min, 58-60°C for 1 min and 72°C for 2 min.…”

“…Amplified fragments were resolved in 3% agarose gel in a 1X TAE buffer. The gels were stained with ethidium bromide (0.5μg/ml) and visualized under UV light and documented in gel documentation system (Bio Rad, U.S.A)" [14].…”

Mapping of Quantitative Trait Loci for Scab Resistance in Apple (Malus × Domestica)

“…In one of our studies marker based screening of F1 derived from cross of variety Firdous and another variety Gala, was undertaken [28]. The same races were used to analyse the resistance pattern of the derived population.…”