POTATO APICAL LEAF CURL DISEASE SCALE FOR SCREENING OF ADVANCED POTATO HYBRIDS USING NOVEL AGRO-INOCULATION TECHNIQUE

Abstract

Potato apical leaf curl disease (PALCD) caused by ToLCNDV has emerged as a serious threat to potato
cultivation in India. Host resistance to the virus is the potent strategy to curb the menace of this disease. Identification of
potato germplasm free from ToLCNDV is a major challenge for healthy seed production and also for an effective resistance
breeding programme. Novel and simple agro-inoculation of ToLCNDV was done to select resistant genotypes of potatoes. A
set of 9 advanced hybrids and 4 control varieties were evaluated for resistance to ToLCNDV under controlled conditions at
ICAR-Central Potato Research Institute, Shimla. Clear symptoms were visible in susceptible genotypes within 30 days after
the first inoculation. Based on symptoms of the disease, a scale (0-5) was developed for ToLCNDV resistance screening.
Phenotyping results showed the resistant reaction of SM/00-42, SM/00-120 and VMT5-1 to ToLCNDV. However, virus load
quantification of inoculated plant samples revealed low virus load in LBY 18, VMT5-1 and SM/00-42. All the four control
varieties showed moderately susceptible to susceptible reaction with Kufri Pukhraj showing the highest virus load among
all genotypes. The hybrid, SM/00-42 was found to promising due to its resistant reaction and very low virus load. This can
be effectively utilized in ToLCNDV resistance breeding or direct deployment after agronomic evaluation. Moreover, the
scale developed in the present study could be used in preliminary screening for the disease.