TY - JOUR
T1 - Virulence variability across the Alternaria spp. population determines incidence and severity of alternaria leaf spot on rapeseed
AU - Al-lami, Hebba F.D.
AU - You, Ming P.
AU - Mohammed, Akeel E.
AU - Barbetti, Martin J.
PY - 2020/4/1
Y1 - 2020/4/1
N2 - Alternaria leaf spot of Brassicaceae can be a devastating disease caused by several species of Alternaria. Differences in virulence (disease incidence and severity) and consequent defoliation were evaluated for 101 isolates across 10 Alternaria spp. (Alternaria alternata, A. brassicae, A. conjuncta, A. ethzedia, A. eureka, A. hordeicola, A. infectoria, A. japonica, A. metachromatica, and A. tenuissima) on seedlings of Brassica napus ‘Thunder TT’. In terms of disease incidence, severity, and defoliation, all isolates tested were virulent, but levels of isolate virulence varied within and between Alternaria spp. tested. Virulence also varied in relation to the disease assessment parameter used. A. japonica showed the highest virulence and overall mean values of percentage leaf disease incidence (%LDI 97.5), percentage leaf area diseased (%LAD 90.0) and percentage leaf senescence index (%LSI 70.0), followed by A. brassicae with 65.0, 55.0, and 35.0, A. ethzedia with 50.9, 41.8, and 15.9, and A. alternata with 48.4, 41.1, and 14.8, for %LDI, %LAD, and %LSI, respectively. The remaining Alternaria spp. also expressed varying levels of virulence in relation to the particular disease parameter used. These findings highlight the variation in relative levels of virulence, in terms of disease incidence, severity, and defoliation, within and between Alternaria spp. associated with leaf spot on rapeseed and reflect the relative importance of different pathogen populations of Alternaria spp. In particular, the potential of A. japonica and A. ethzedia to be significant pathogens of rapeseed in Australia, along with A. brassicae and A. alternata, is highlighted.
AB - Alternaria leaf spot of Brassicaceae can be a devastating disease caused by several species of Alternaria. Differences in virulence (disease incidence and severity) and consequent defoliation were evaluated for 101 isolates across 10 Alternaria spp. (Alternaria alternata, A. brassicae, A. conjuncta, A. ethzedia, A. eureka, A. hordeicola, A. infectoria, A. japonica, A. metachromatica, and A. tenuissima) on seedlings of Brassica napus ‘Thunder TT’. In terms of disease incidence, severity, and defoliation, all isolates tested were virulent, but levels of isolate virulence varied within and between Alternaria spp. tested. Virulence also varied in relation to the disease assessment parameter used. A. japonica showed the highest virulence and overall mean values of percentage leaf disease incidence (%LDI 97.5), percentage leaf area diseased (%LAD 90.0) and percentage leaf senescence index (%LSI 70.0), followed by A. brassicae with 65.0, 55.0, and 35.0, A. ethzedia with 50.9, 41.8, and 15.9, and A. alternata with 48.4, 41.1, and 14.8, for %LDI, %LAD, and %LSI, respectively. The remaining Alternaria spp. also expressed varying levels of virulence in relation to the particular disease parameter used. These findings highlight the variation in relative levels of virulence, in terms of disease incidence, severity, and defoliation, within and between Alternaria spp. associated with leaf spot on rapeseed and reflect the relative importance of different pathogen populations of Alternaria spp. In particular, the potential of A. japonica and A. ethzedia to be significant pathogens of rapeseed in Australia, along with A. brassicae and A. alternata, is highlighted.
KW - alternaria leaf spot
KW - Alternaria spp.
KW - Brassica napus
KW - rapeseed
KW - virulence
UR - http://www.scopus.com/inward/record.url?scp=85077973946&partnerID=8YFLogxK
U2 - 10.1111/ppa.13135
DO - 10.1111/ppa.13135
M3 - Article
AN - SCOPUS:85077973946
SN - 0032-0862
VL - 69
SP - 506
EP - 517
JO - Plant Pathology
JF - Plant Pathology
IS - 3
ER -