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Characterization of mating type ( MAT ) alleles differentiated by a natural inversion in Sclerotinia minor
Author(s) -
Chitrampalam P.,
Pryor B. M.
Publication year - 2015
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/ppa.12305
Subject(s) - biology , sclerotinia sclerotiorum , homothallism , chromosomal inversion , genetics , mating type , inverted repeat , locus (genetics) , minor allele frequency , botany , allele , gene , chromosome , genome , karyotype , allele frequency
A recent study on fungal mating type genes revealed two MAT alleles within homothallic Sclerotinia sclerotiorum differentiated by an inversion, Inv− (inversion negative) and Inv+ (inversion positive). An analysis of mating type in closely related S. minor was conducted to shed light on the evolution of this MAT inversion. Inv− and Inv+ MAT alleles were identified in S. minor and were characterized. Both MAT alleles in S. minor were flanked by APN 2 and SLA 2 , and consisted of two idiomorphs fused as in other homothallic ascomycetes. However, in the Inv+ MAT , the 3·6 kb MAT region was inverted relative to the Inv− MAT . Except for the inversion, both Inv− and Inv+ MAT in S. minor were equal in size and identical in nucleotide sequence. The MAT inversion in Inv+ S. minor was at exactly the same place as in Inv+ S. sclerotiorum and affected three of four MAT genes: MAT 1‐1‐1 was truncated and MAT 1‐2‐4 and MAT 1‐2‐1 were inverted. Unlike S. sclerotiorum , expression of MAT genes did not differ between Inv− and Inv+ S. minor . The 250 bp inverted repeat motif that flanked the inverted MAT region in S. sclerotiorum and believed responsible for the MAT inversion was also found in S. minor , but was 256 bp. Depending on the MAT genes, 93–96% nucleotide identity was observed between Sclerotinia species. Both Inv+ and Inv− MAT S. minor and S. sclerotiorum isolates were commonly found in lettuce fields of Arizona along with MAT heterokaryons.