Association of melanin content with conidiogenesis in Bipolaris Sorokiniana of barley (Hordeum vulgare L.)

Abstract

Sixty-seven isolates of Bipolaris sorokiniana of barley, belonging to three groups (black, white and mixed) were studied to find an association of melanin with the spore production of the fungus. Conidiogenesis in black, white and mixed subpopulation of B. sorokiniana was positively correlated with melanin content/g of mycelium. Primary hyphae of black and mixed subpopulation differentiated into secondary hyphal structures which subsequently produced conidiophores and conidia. Primary hyphae could not differentiate into secondary hyphae and subsequently conidiophores and conidia in white subpopulation. A melanin containing mutant developed from white subpopulation regained its ability to differentiate into secondary hyphae, conidiophores and conidia. Results showed that melanization of mycelia B. sorokiniana mycelia is an important factor for conidia production.

Emergence of Aggressive Population in the Bipolaris sorokiniana of Barley (Hordeum vulgare L.) Through Anastomosis

“…White isolates of B. sorokiniana were reported to be melanin deficient and lower frequency of this population was probably due to poor fitness and survival [8]. Thus, natural condition selection might have favoured those isolates that have melanin in their cell wall.…”

“…These pieces were dried in sterile blotter paper, then transferred to Potato Dextrose Agar (PDA) medium under aseptic conditions and incubated at 25°C for 8 days. Populations were characterized morphologically as described by Bashyal et al [8]. Frequency distribution of white, black and mixed (white and black) population was scored on different barley genotypes.…”

“…Compatible white (B26) and black (B4) isolates were selected and 5 mm 2 discs from both the isolates were placed on PDA medium at a distance of 15 mm [8] and Petri plates were incubated at 25°C. After 8 days when the hyphae of both the isolates contacted, agar strip of 10 mm 9 5 mm was marked from the center of contact point and agar pieces of 1 mm 2 were taken out from the marked area and inoculated individually on PDA plates.…”

“…Radial growth (cm) was measured by placing a mycelial disc (5 mm diameter) in the center of the Petri plate and incubated at 25°C for 8 days. Colony colour was recorded on the 8th day [8]. Spore production was recorded by excising 5 mm 2 colony area from five different places of the colony at a distance of 5 cm away from the center using a cork borer as described earlier.…”

“…Based on colony morphology, melanin content and Randomly Amplified Polymorphic DNA (RAPD) markers, B. sorokiniana isolates of barley were broadly grouped in black, mixed (black and white) and white population. Isolates of mixed populations were most predominant in nature [8].…”