Inheritance Mode of Virulance in Nectria Haematococca Matting Population I

Abstract

The difference in virulence of two standard strains in colonizing seedling hypocotyle and fruit exocarp suggested that multi-locus control of this trait. Whereas, Strain ATCC18099 was unable to infect uninjured cucumber and Zucchini fruits, both strains had high virulence against seedlings. The inheritance mode of this trait was studied by tetrad and random ascospore analysis with ascospores obtained from reciprocal crossings between ATCC18098 and ATCC18099. Segregation of MAT and perithecial color was also examined in both types of ascospore analyses. The results of tetrad analysis indicated 4:4 segregation for the high virulence associated with strain ATCC18098 in each tetrad, suggesting a Mendelian mode of inheritance. In random ascospore analysis, chi-square test supported that progeny with and without high virulence segregated in 1:1 in each cross and linkage analysis showed that such trait segregated independently from either MAT or perithecial color trait.