Development of a specific marker for detection of a functional AvrLm9 allele and validating the interaction between AvrLm7 and AvrLm9 in Leptosphaeria maculans

• Published in: Molecular biology reports Vol. 47; no. 9; pp. 7115 - 7123
• Main Authors: Liu, Fei, Zou, Zhongwei, Huang, Shuanglong, Parks, Paula, Fernando, W. G. Dilantha
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-09-2020; Springer Nature B.V
• Subjects: Alleles; Animal Anatomy; Animal Biochemistry; Biomedical and Life Sciences; Blackleg; Brassica napus - microbiology; Fungal Proteins - genetics; Genes; Histology; Inoculation; Leptosphaeria - genetics; Leptosphaeria - pathogenicity; Leptosphaeria maculans; Life Sciences; Morphology; Original Article; Plant Diseases - genetics; Plant Diseases - microbiology; Single-nucleotide polymorphism; Virulence Factors - genetics; Canada; Avirulence gene; Brassica napus; Leptosphaeria maculans; AvrLm4-7; AvrLm9
• ISSN: 0301-4851; 1573-4978
• DOI: 10.1007/s11033-020-05779-8

Blackleg, which is caused by the fungus
Leptosphaeria maculans
(
L. maculans
), is a major disease of canola in western Canada and worldwide. Long-term use of one source of resistance could cause the breakdown of its effectiveness. Therefore, appropriate use of
R
genes is very important, and knowledge about the distribution of avirulence genes is a prerequisite for effectively deploying resistance. Of the 14 avirulence genes identified in
L. maculans
,
AvrLm5
and
AvrLm9
were recognized as the two alleles of the same gene based on two single nucleotide polymorphisms, C
85
T and G
164
A/C. In this study, a specific marker was developed to identify
AvrLm5
and
AvrLm9
based on two single nucleotide polymorphisms, C
85
T and G
164
A/C, which are responsible for the function of
AvrLm9
. The specific marker can be used to discriminate the
AvrLm9
from
avrLm9
accurately in
L. maculans
isolates, which is consistent with inoculation tests in isolates without
AvrLm4-7
. This specific marker was used to screen 1229 isolates collected from fields in the years 2014 through 2016 in Manitoba. From 68 to 84% of the isolates were found to contain the
AvrLm9
allele; while 4–7% of them were avirulent on the variety Goéland with
Rlm9
loci. Furthermore, no isolates having both
AvrLm9
and
AvrLm7
were detected using a cotyledon test, while 67% to 84% of isolates contained both avirulence genes via PCR detection, implying suppression of
AvrLm9
by
AvrLm7
. In addition, avirulence gene profiles of the other 10 avirulence alleles were examined with the 1229 isolates using cotyledon tests or PCR amplifications. Taken together, this research enables the fast identification of
AvrLm5/9
, provides the
Avr
genes’ landscape of western Canada and elaborates the relationship between
AvrLm9
and
AvrLm7
using isolates from grower fields.