EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
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SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION<br />
GENETICS<br />
Race Scenario <strong>of</strong> Fusarium oxysporum f sp. ciceris,<br />
wilt pathogen <strong>of</strong> chickpea (Cicer arietinum L.)<br />
M. Sharma, A. Nagavardhini, S. Pande<br />
International Crop Research Institute for Semi-Arid tropics (ICRISAT), Patancheru, Hyderabad-502<br />
324, Andhra Pradesh, India.<br />
E-mail: mamta.sharma@cgiar.org<br />
Fusarium wilt caused by Fusarium oxysporum f.sp. ciceris (Foc) is most wide<br />
spread and predominant disease in all chickpea growing areas worldwide.<br />
Although the FW resistant sources are available, but due to the variability in<br />
pathogen, the efficiency <strong>of</strong> resistant cultivars is limited. To understand the<br />
variability/ race scenario in Foc in India, out <strong>of</strong> total repository <strong>of</strong> 274 isolates <strong>of</strong><br />
Foc build from the period <strong>of</strong> 1995 - 2010, 110 isolates were selected for cultural,<br />
morphological, virulence and genomic diversity representing various chickpea<br />
agro-climatic zones in India. The isolates showed variation in colony colour, type<br />
<strong>of</strong> mycelium and growth pattern. Wide variation in conidial morphology<br />
(microconidia and macroconidia) and chlamydospore formation with respect to<br />
shape, size and proportion was observed. Significant pathogenic diversity was<br />
found among the 98 isolates based on their virulence reaction on 10 standard<br />
differentials <strong>of</strong> chickpea. Clustering <strong>of</strong> isolates based on percentage disease<br />
incidence at 85% similarity resulted in 14 major pathogenic groups. In addition to<br />
4 races reported earlier from India, occurrence <strong>of</strong> new pathogenic races and<br />
existence <strong>of</strong> multiple races at one place was observed. Race 6 reaction reported<br />
from California and Mediterranean basin was found in some locations in central,<br />
north east and north west zones <strong>of</strong> India. Diversity Arrays Technology (DArT) was<br />
used for the first time to understand the diversity in Foc isolates. Restriction<br />
enzyme combination PstI/HpaII was selected to construct the Foc DArT array.<br />
Genotyping <strong>of</strong> 110 isolates was done by labelling the genomic representations<br />
with the fluorescent nucleotides cy3-dUTP and cy5-dUTP. Out <strong>of</strong> 1813<br />
polymorphic markers, 1141 exhibited 90% call rate. The Dendroscope analysis<br />
and principle coordinate analysis <strong>of</strong> 1813 polymorphic markers grouped 110 Foc<br />
isolates in to 4 major groups with subgroups in each group. Each group has<br />
isolates from different regions. The study indicates changed scenario <strong>of</strong> races in<br />
Indian population <strong>of</strong> the pathogen and existence <strong>of</strong> multiple races with in region.<br />
The information generated is <strong>of</strong> significant importance in resistance breeding<br />
program in chickpea.<br />
Keywords: chickpea, DArT, Fusarium wilt, races<br />
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