In vivo and in vitro validation of powdery mildew resistance in garden pea genotypes

Powdery mildew is one of the serious diseases of garden pea which causes a large number of yield losses. Genetic resistance is quite effective, being cost-effective and environment friendly than fungicide applications. In the present studies an initial attempt has been made to identify resistant genotypes against powdery mildew disease developed from hybridization followed by validation of the disease. The experimental material comprised of 48 genotypes that includes 44 advanced breeding lines was evaluated for powdery mildew incidence in Randomized Complete Block Design with three replications at two locations under field conditions [Palampur (winter 2017-18 and 2018-19) and Kukumseri (summer 2018)] and in vitro at Palampur [detached leaf method and polyhouse conditions]. Ten lines viz., SP7, SN-1, SN-6-1, SN-7-1, SN-2, SN-5-2, SN-6-2, SN-10, SN-21 and SP-281 showed resistant reaction along with check Palam Sumool while 27 lines were identified as moderately resistant in comparison to susceptible check Azad P-1. Besides, six lines namely, SP-2, SP-5, SP-10, SP-24, SA-4 and SP-12-1 gave moderately susceptible reaction along with checks Pb-89 and Palam Priya. Only, SP-19 was categorized as susceptible. The high yielding lines SP-3, SP-6 and SP-22 showed moderately resistant reaction in both natural and artificial conditions. Validation of resistance using molecular markers revealed that neither the parental genotypes nor the progenies possess the er1 gene of JI1559. The er2 linked marker ScOPX-17(1700) was polymorphic between Palam Sumool and Palam Priya but the marker didn't show polymorphism between er2 harboring line (JI2480). These results suggested that the lines showing resistance under field conditions may have some other genes or alleles for resistance and further confirmation is needed by developing mapping populations with specific gene or gene combinations.