Stable Formation of Fruiting Body in Cordyceps bassiana

Abstract

In order to breed a Cordyceps bassiana isolate that stably forms fruiting body in artificial cultivation, isolates derived from subculturing and single spores were tested through mating. From C. bassiana EFCC 783, three subcultured isolates EFCC 2830, EFCC 2831 and EFCC 2832 were obtained and fourteen single conidial isolates were obtained from these three subcultured isolates. Two different morphological types were found in the fourteen single conidial isolates. One type was able to form synnemata and another type was not able to form synnemata. Since switch of morphological type was not observed despite their continuous subculturing, cross was performed between the two types and the formation of fruiting body was examined. Ascospores were obtained from a selected fruiting body formed by hybrid of the cross. Self-cross and combinational cross of the ascospore-derived isolates generated hybrids that stably produce high quality fruiting body in artificial media.

Keywords: Cordyceps bassiana; Mating type; Perithecial fruiting bodies; Single conidial isolates; Synnemata.

Fig. 1

Two morphological features shown by 14 single conidial isolates from Cordyceps bassiana subcultures EFCC2830, EFCC 2831 and EFCC 2832. Right figure shows fruiting body formation type (bottom) and no fruiting body formation type (top).

Fig. 2

Fruiting body of Cordyceps bassiana formed by self-cross of EFCC 2832-3 single conidial isolates.

Fig. 3

Fruiting body formation by single ascospore isolates from self-cross of Cordyceps bassiana EFCC 2832-3. Numbers (1-6) indicate single ascospore isolates (from 2832-3-1 to 2832-3-6). Top (a), mycelila growth of the six single ascospore isolates on fruiting body formation media. Bottom (b), fruiting body formation by cross of two different single ascospore isolates.

Fig. 4

Fruiting body formation by single ascospore isolates from self-cross of Cordyceps bassiana EFCC 12511. Alphabet (a, b ,c, d, e, f, g, h, i) indicates single ascospore isolates (from 12511-a to 12511-i). Example of fruiting body formed by cross of two different single ascospore isolates.

Fig. 5

Fruiting body formed by cross of single ascospore isolates of Cordyceps bassiana EFCC 12511-a × b. Numbers (1-6) indicate single ascospore isolates (from EFCC 12511-a × b-1 to EFCC 12511-a × b-10).