Relationship between Yield Components and Partial Resistance to Lecanicillium fungicola in the Button Mushroom, Agaricus bisporus, Assessed by Quantitative Trait Locus Mapping

Abstract

b Dry bubble, caused by Lecanicillium fungicola, is one of the most detrimental diseases affecting button mushroom cultivation. In a previous study, we demonstrated that breeding for resistance to this pathogen is quite challenging due to its quantitative inheritance. A second-generation hybrid progeny derived from an intervarietal cross between a wild strain and a commercial cultivar was characterized for L. fungicola resistance under artificial inoculation in three independent experiments. Analysis of quantitative trait loci (QTL) was used to determine the locations, numbers, and effects of genomic regions associated with drybubble resistance. Four traits related to resistance were analyzed. Two to four QTL were detected per trait, depending on the experiment. Two genomic regions, on linkage group X (LGX) and LGVIII, were consistently detected in the three experiments. The genomic region on LGX was detected for three of the four variables studied. The total phenotypic variance accounted for by all QTL ranged from 19.3% to 42.1% over all traits in all experiments. For most of the QTL, the favorable allele for resistance came from the wild parent, but for some QTL, the allele that contributed to a higher level of resistance was carried by the cultivar. Comparative mapping with QTL for yield-related traits revealed five colocations between resistance and yield component loci, suggesting that the resistance results from both genetic factors and fitness expression. The consequences for mushroom breeding programs are discussed. D ry bubble, caused by the fungal pathogen Lecanicillium fungicola (Preuss) Zare et Gams (formerly Verticillium fungicola)is one of the most detrimental diseases that affect cultures of Agaricus bisporus (Lange) Imbach worldwide. Undifferentiated spherical mass (dry bubble), stipe blowout, and spotty cap (17, 21) characterize L. fungicola infection, leading to yield decreases and severe economic losses. Today, control of L. fungicola relies on prophylactic measures and the use of fungicides. However, drastic specifications for the application of chemicals for pest and disease control in mushroom farms, together with the emergence of fungicide tolerance, lead to the consideration of mushroom breeding for resistance to disease as an environmentally sustainable and effective way to limit pathogen epidemics.Potential sources of resistance to dry bubble have been identified in wild types of A. bisporus, but no complete resistance has been found (6, 15). Thus, wild strains from the Sonoran desert belonging to A. bisporus var. burnettii showed a high level of tolerance for L. fungicola infection (18). In a recent study, the analysis of segregation data for dry-bubble resistance in progeny derived from an A. bisporus var. bisporus ϫ A. bisporus var. burnettii intervarietal cross suggested polygenic inheritance of the partial resistance to L. fungicola carried by A. bisporus var. burnettii (8). The introgression of such complex genetic resistance into new button mushroom cultivars through conventional...

Tolerance to Lecanicillium fungicola and yield of Agaricus bisporus strains used in Brazil

“…Dry bubble, caused by the fungal pathogen L. fungicola (Preuss) Zare and Gams (formerly Verticillium fungicola), is one of the most detrimental diseases that affects production of A. bisporus (Lange) Imbach worldwide (Foulongne-Oriol et al, 2012). Undifferentiated spherical masses (dry bubble), differential growth of the stipe and subsequent rupturing, and circular lesions on the pileus surface are characteristic symptoms of L. fungicola infection, all leading to severe economic losses (North and Wuest, 1993).…”

Association Mapping Reveals Genetic Loci Associated with Important Agronomic Traits in Lentinula edodes, Shiitake Mushroom

“…Linkage mapping was first introduced to understand the genetic basis of quantitative traits since the 1980s (Lander and Botstein, 1989 ). Since the 2000s, this approach has been successfully used to map QTLs controlling important traits in several mushroom species, such as A. bisporus (Foulongne-Oriol et al, 2012a , b ), Pleurotus ostreatus (Larraya et al, 2002 , 2003 ) and P. eryngii (Im et al, 2016 ). However, linkage mapping requires the construction of segregating populations, which is time-consuming and laborious, thus limiting its application in breeding programs.…”

Transcriptional Changes on Blight Fruiting Body of Flammulina velutipes Caused by Two New Bacterial Pathogens

“…Phenolic substrates of the active tyrosinase were oxidized, proportional to the damage detectable on the mushroom pileus (Soler-Rivas et al, 1998). In addition, melanin biosynthesis was also reported to relate to resistance of A. bisporus to pathogens including P. tolaasii and L. fungicola, as toxic melanins circumscribe the growth of the pathogens (Foulongne-Oriol et al, 2012). In the young fruiting body of diseased F. velutipes, melanin synthesis derived from tyrosine oxidation by tyrosinase caused brown spot of pileus, as well as participated in defense of F. velutipes to pathogenic bacteria.…”