Mushroom Culture

Genetic Improvement of Mushrooms

Majority of the cultivated edible fungal species belong to Basidiomycotina group with small majority belonging to Ascomycotina group. One must know the biological behaviour of mushrooms so as to develop a programme for further improvement in qualities.

It is well understood that the yield and quality of a particular mushroom species depend on the genetic makeup of the mushroom variety and the environmental conditions in which it is growing.The interaction between genes and environmental conditions determines the overall performance of a mushroom variety, including its characters and behaviour. Following different methods have been adopted for the genetic improvement of button mushroom from time to time :

• Introduction
• Selection
• Anastomosis
• Hybridization
• Mutation
• Protoplast fusion
• Genetic Engineering.

1. INTRODUCTION :
It is the quickest and an easy method of crop improvement. Here a number of surveys are made , various isolates growing in different environment are collected and screened for their yield performance at a changed environment. This introduction proceeds for isolation and selection of superior type for their direct use and it builds up the genetic base for further improvement in performance under the breeding programme. Large scale adoption of strain S-11 and RRL-89 in Himachal Pradesh and Jammu & Kashmir, respectively in India are the results of the introduction of this species. Similarly K-32 and K-26 were found to be the best amongst five strains of Agaricus bitorquis.

Fig. 4.2 Field trials conducted for the evaluation of strains

2. SELECTION :
It is the process of retention of desired genotypes and elimination of undesirable ones within a strain, but its success depends upon the presence of high additive genetic variance and the least influence of genotype x environment interaction on the expression of trait to be selected. In button mushrooms, selection can be made from single spore, multispore or tissue culture techniques. Single monosporic culture technique is helpful only in homothallic species ( species bearing the sex structures in the same thallus) like Agaricus bisporus and A. subfloccosus , but in case of heterothallic species like A.bitorquis, A.campestris , A arvensis etc ; selection is done using multispore or tissue culture technique.

Fig. 4.6 Field trials conducted for the evaluation of strains of milky mushroom