ASSOCIATION OF NONPATHOGENIC FUSARIUM OXYSPORUM SPECIES WITH CULTURED SHOOT APICES OF BANANA (MUSA ACUMINATA) CULTIVARS

Abstract

Fusarium wilt of banana caused by Fusarium oxysporum f. sp.cubense is the most devastating disease worldwide.
Management of disease is difficult through use of chemicals and very few cultivars are resistant. Nonpathogenic
strains of Fusarium oxysporum act as biocontrol agent for the wilt disease by antagonizing and competing with
the pathogenic strains for nutrients and root colonization sites. Shoot apices cultures of four banana cultivars
Alpan, Malbhog, Robusta and Kothia on MS basal medium supplemented with 4.5mgL-1BAP and 0.2mgL-1IAA
resulted in adventitious shoot differentiations. Some cultures showed appearance of endophytic fungal mycelium
from the explant surface. Macroscopic and microscopic characterization of the isolated fungus suggested it to be
Fusarium oxysporum. The fungal isolates were tested for their pathogenicity in tissue cultured plants of Fusarium
wilt susceptible banana cv. Malbhog through root dip method. The non appearance of disease symptoms
established the nonpathogenic status of the isolated Fusarium oxysporum strain. The frequency of association of
non pathogenic Fusarium oxysporum was more in susceptible cvs. Alpan (13.65%) and Malbhog (13.07%)
compared to resistant cv. Kothia (4.59%). Thus, there were endophytic association of non pathogenic Fusarium
oxysporum strains in banana cultivars, which might be the reason of absence of the disease in the area.