Distribution of Apple Scab Race Flora and Identification of Resistant Sources against Venturia inaequalis in Kashmir

Abstract

A B S T R A C T Apple scab caused by a fungus Venturia inaequalis cause enormous losses to growers both qualitatively and quantitatively. In order to manage the crop, farmers routinely spray 8-12 fungicides from pink bud till harvest. Hence, the best strategy to manage the disease is planting apple scab resistant cultivars. In the present study, four races viz., (0), (1), (2) and (1, 2) were reported from various commercial apple growing regions of Kashmir. Apple scab races were spatially distributed in all apple growing regions of Kashmir. Race 1 was most prevalent among the four races. Screening of 31 apple genotypes under controlled conditions revealed majority of commercial cultivars susceptible. Genotypes carrying RVi3 to RVi13 scab resistance genes along with the cultivars American Apirouge, H27, Shireen and Firdous (latter two contain RVi6 scab resistance gene) were found resistant to all the four races present in Kashmir. Resistant genotypes reported in the present study can easily be exploited by breeders for management of apple scab resistance using marker assisted selection approach.

Strong Genetic Differentiation between Generalist Populations of Venturia inaequalis and Populations from Partially Resistant Apple Cultivars Carrying Rvi3 or Rvi5

“…Detached leaf assay showed that virulence towards Rvi1 is common in the local V. inaequalis population. This is in accordance with other studies where 87% [16] and 71% [15] of V. inaequalis isolates were virulent on 'Golden Delicious' (Rvi1), in Europe and India, respectively. In contrast, no conidia from other hosts caused an infection on the leaves of Rvi3 or Rvi5 cultivars.…”

“…Moreover, the sequence and functional characterization of Rvi6, Rvi15, and, most recently, Rvi12 has been carried out, supported by transgenic experiments [10][11][12][13]. Plant-pathogen interactions have been studied to identify new R-genes [14] and to profile the distribution of pathogen races in large areas [15,16]. Recently, a long-term study with a broad geographic scope has been published on the practical efficiency of R-genes monitored with scab race indicator cultivars [4].…”