Restriction Fragment Length Polymorphisms in the Mushrooms Agaricus brunnescens and Agaricus bitorquis

Abstract

Two Agaricus species, A. brunnescens (a commercial mushroom) and A. bitorquis (a wild, edible species), were examined for restriction fragment length polymorphisms. EcoRI-digested nuclear DNA from isolates of both species were cloned in plasmid vector pUC18. Ten random recombinant clones were used in Southern DNA-DNA hybridizations to probe EcoRI-digested DNA from 11 A. brunnescens isolates (7 commercial, 2 wild type, and 2 homokaryotic) and 7 A. bitorquis isolates. Most cloned fragments were polymorphic in both species. There were fewer different genotypes than expected, however, in the sample of commercial A. brunnescens strains. DNA from homokaryotic strains showed fewer bands in most hybridizations than DNA from heterokaryotic strains. All A. bitorquis isolates could be distinguished from each other as well as from every A. brunnescens strain. Putative homokaryons were detected by the loss of polymorphic bands among protoplast regenerates from one commercial strain and two strains collected in the wild.

Investigation of Mitochondrial Transmission in Selected Matings between Homokaryons from Commercial and Wild-Collected Isolates of Agaricus bisporus (= Agaricus brunnescens )

“…The homokaryotic and heterokaryotic Ag2-23 (homokaryon of Ag2) II 6.7, 1.4 5.8 6.3 No No This study a The homokaryons derived from any given heterokaryon carry the mt genotype of the heterokaryon. b Values refer to the sizes in kilobases of EcoRI fragments hybridized to probes described in Castle et al (5). c Agl-l is a homokaryotic single-spore isolate of Ag2.…”

“…RFLPs were (ii) Dutch. For verification of nuclear types, the plasmids used as the genetic markers to verify homokaryon or hetero-p33n1O and p33n25, first described by Castle et al (5,6), karyon status (6). were used.…”

“…A simple, unambiguous breeding approach, which uses protoplast formation and regeneration for the isolation of self-sterile homokaryons from self-fertile heterokaryons, has been developed (5,6). Nuclear restriction fragment length polymorphisms (RFLPs) have been successfully used as the genetic markers to identify the two unique nuclear types in a heterokaryon (6).…”

Cloning and Characterization of NADP-Mannitol Dehydrogenase cDNA from the Button Mushroom, Agaricus bisporus , and Its Expression in Response to NaCl Stress

“…Its cultivation, trade, and processing represent important economic activities, especially in the European Community and the United States. Due to the low degree of genetic variation in commercial strains (5), it is increasingly difficult to obtain strains that meet specific demands for the market of fresh or processed products. The production of improved strains by conventional breeding methods has been limited due to the aberrant life cycle of A. bisporus, which usually generates heterokaryotic spores with two parental nuclei that show almost no genetic exchange (46).…”

Crosses among Homokaryons from Commercial and Wild-Collected Strains of the Mushroom Agaricus brunnescens (= A. bisporus )

“…The recovery of self-sterile, presumably homokaryotic, strains by micromanipulation of spores from tetrasporic basidia (6) or by screening random single-spore isolates (10, 23), however, is time-consuming and difficult. Recently, another method for obtaining homokaryons was reported (1,3). When protoplasts are produced from a heterokaryon and allowed to regenerate mycelia, approximately 1 in 10 is homokaryotic.…”