Development of Agaricus bisporus hybrids and their evaluation for higher yield

Abstract

Agaricus bisporus (Lange) Imbach, the white button mushroom, is the major edible mushroom species cultivated throughout the world. Despite its economic potential, only a few genetic studies have been carried out concerning A. bisporus, due to its peculiar life cycle. Button mushroom is a secondary homothallic fungi and breeding is difficult as most of the spores are heterokaryotic in nature. Therefore, the present investigation as undertaken to develop the hybrid(s) of A. bisporus and their evaluation for higher yield. One thousand six hundred forty two single spore isolates were raised from parental strains, namely, A-15, S 11, S140 and U3 of A. bisporus. Out of these only 36 single spore isolates were homokaryons. ISSR studies revealed homokaryons lacking amplification products at multiple loci. Out of the 253 crosses, only seven crosses between the parents were compatible. The yield studies showed that that newly developed hybrid Hb4 produced highest average yield (26.94 kg/100 kg compost) and also exhibited better qualities as compared to other isolates. Percentage of polymorphism by RAPD markers were 60.00 per cent. All the isolates exhibited identical ITS length of approximately near about 650 bp. The ITS region showed single nucleotide polymorphisms (SNPs) at six nucleotide positions of 281, 290, 291,292, 293, 295 and 300 base pair in the ITS region of the best developed hybrids (Hb1, Hb4) and parent strains, namely, A-15 and U3 of A. bisporus.