Volume 19 Part 1 Article 69
Title: Molecular characterization of browning resistant hybrids of button mushroom using retro-element based markers
Author: Shwet Kamal, Mamta Gupta, Manjit Singh, Om Parkash Ahlawat, Ramesh Chandra Upadhyay, Ved Parkash Sharma
Post-harvest browning in white button mushroom is a major problem affecting the quality and marketability of this mushroom. It has been shown that enzymatic browning of mushrooms is caused by polyphenol oxidases (PPOs: tyrosinases and laccases) and peroxidases through an enzyme-catalysed oxidation of phenolic substrates into quinones. These products undergo subsequent reactions leading to the formation of the dark pigment melanin. In the present study, 361 hybrids were produced using non-fertile isolates from 11 strains and evaluated for their browning reaction by applying double streak mechanical injury using a fork. Forty-one hybrids were selected on the basis of varying browning resistance (after two hours of mechanical injury) and yield. Five of these with high browning resistance have been finally selected for large scale evaluation. Further, the five high browning resistant hybrids were characterized using ISSRs, SSRs, and retro-element based markers. In the study, to amplify around pairs of insertion sites through IRAPs technique, we have used outward facing primers of the two consecutive retro-elements. For REMAP studies, we have used successful IRAP primers along with microsatellite primers. These retro-element based markers have shown very high resolution between the parents and hybrids. It can be inferred from the study that these can be effectively used in confirmation of hybridization in Agaricus breeding programme. We have also got a number of fertility linked markers in Agaricus, strain specific markers in different strains of Agaricus and also genus and species specific markers in different mushrooms. Retro-element based markers showed high diversity in Agaricus bisporus, where diversity is always revealed to be very low with most of the other marker systems.