Vol. 10, Issue 11 (2021)

Author(s):
NV Naidu, SJ Mallikarjuna and N Sabitha

Abstract:
Sugarcane yellow leaf virus, has been identified as the causative virus of the disease ScYLV, which spreads through vegetative cuttings and one aphid species viz., Melanaphis sacchari. Sugarcane yellow leaf virus (ScYLV), a phloem-limiting virus belonging to family Luteoviridae and genus Polerovirus͘. In India, the occurrence of YL were reported all over the country and susceptible cultivars in commercial fields reach up to 100%. The most characteristic symptom of YLD is a distinct yellowing of the lower surface of the leaf midrib on young leaves at the apex of the mature plants, which can extend laterally to the leaf lamina. The yellowing of the midrib may turn pink or have a reddish tinge. Older leaves show a red coloration of the midrib on the adaxial surface. The leaf blade becomes bleached, proceeding from the tip toward the base of the leaf, and tissue necrosis can eventually take place. The yellowing can spread into the leaf blade and mid-veins can turn pink in severely infected plants. A serological method of detection is the most common since it is rapid, inexpensive and robust. RT-PCR can be rapidly implemented in independent laboratories after the basic protocol and primer sequences are made available. RT-PCR was the first technique developed to diagnose the presence of a virus in symptomatic plants with primers specific to luteoviruses. Variation in pathogenicity among genotypes of ScYLV viz., BRA (Brazil), CHN1 and CHN3 (China), CUB (Cuba), HAW (Hawaii), IND (India), PER (Peru), and REU (Re´union Island) has also been reported. Sugarcane yellow leaf virus (ScYLV), naturally infects at least three plant species: sugarcane (Saccharum spp.), the weed Columbus grass (Sorghum almum) and cultivated sorghum (Sorghum bicolor). All three hosts are also colonized by the sugarcane aphid (Melanaphis sacchari), the main vector of ScYLV worldwide. No single method is efficient/available to control YLD and hence an integrated approach involving cultural, chemical, physical methods, host resistance and legislative measures may be adopted for the sustainable management of sugarcane diseases.