AUTHOR=Jenkins Sascha , Taylor Andrew , Jackson Alison C. , Armitage Andrew D. , Bates Helen J. , Mead Andrew , Harrison Richard J. , Clarkson John P. 

TITLE=Identification and Expression of Secreted In Xylem Pathogenicity Genes in Fusarium oxysporum f. sp. pisi

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.593140

DOI=10.3389/fmicb.2021.593140

ISSN=1664-302X

ABSTRACT=<p><italic>Fusarium oxysporum</italic> is a soilborne fungal plant pathogen responsible for causing disease in many economically important crops with “special forms” (<italic>formae speciales</italic>) adapted to infect specific plant hosts. <italic>F. oxysporum</italic> f. sp. <italic>pisi</italic> (FOP) is the causal agent of Fusarium wilt disease of pea. It has been reported in every country where peas are grown commercially. Disease is generally controlled using resistant cultivars possessing single major gene resistance and therefore there is a constant risk of breakdown. The main aim of this work was to characterise <italic>F. oxysporum</italic> isolates collected from diseased peas in the United Kingdom as well as FOP isolates obtained from other researchers representing different races through sequencing of a housekeeping gene and the presence of <italic>Secreted In Xylem</italic> (<italic>SIX</italic>) genes, which have previously been associated with pathogenicity in other <italic>F. oxysporum</italic> f. spp. <italic>F. oxysporum</italic> isolates from diseased United Kingdom pea plants possessed none or just one or two known <italic>SIX</italic> genes with no consistent pattern of presence/absence, leading to the conclusion that they were foot-rot causing isolates rather than FOP. In contrast, FOP isolates had different complements of <italic>SIX</italic> genes with all those identified as race 1 containing <italic>SIX1</italic>, <italic>SIX6</italic>, <italic>SIX7</italic>, <italic>SIX9</italic>, <italic>SIX10</italic>, <italic>SIX11</italic>, <italic>SIX12</italic>, and <italic>SIX14</italic>. FOP isolates that were identified as belonging to race 2 through testing on differential pea cultivars, contained either <italic>SIX1</italic>, <italic>SIX6</italic>, <italic>SIX9</italic>, <italic>SIX13, SIX14</italic> or <italic>SIX1</italic>, <italic>SIX6, SIX13</italic>. Significant upregulation of <italic>SIX</italic> genes was also observed <italic>in planta</italic> over the early stages of infection by different FOP races in pea roots. Race specific <italic>SIX</italic> gene profiling may therefore provide potential targets for molecular identification of FOP races but further research is needed to determine whether variation in complement of <italic>SIX</italic> genes in FOP race 2 isolates results in differences in virulence across a broader set of pea differential cultivars.</p>