In Vitro and Greenhouse Evaluation for Resistance to Early Blight of Potato Isolated from Alternaria alternata
Early blight of
potato is caused by the fungus Alternaria alternata, one of the
most destructive foliar diseases, especially in hot climates under irrigation. It
usually causes leaf spots and tuber blight on potatoes. Potato resistance to
early blight is a quantitative trait, and obtaining successful resistant
cultivars is not simple. Some studies have shown that resistance to early
blight is age-related: early-maturing cultivars are more susceptible than
late-maturing cultivars.
In this study, the
virus free potato seedlings were obtained from the National Plant Gene Bank of
Iran during 2008-2009 and were inoculated in vitro with a
culture filtrate of A. alternate. Seven cultivars (Ells, Picasso,
Maradona, Marfona, Delta, Casmos and Desiree) were conducted that were
propagated through nodal cutting every three month and kept in growth chamber
at 25˚C ± 1˚C light with a period of 16 h light and 8 h dark. The leaflets
received a 1000-μl droplet of the A. alternata culture
filtrate and were inoculated by spraying with a suspension of 105 conidia/ml
of isolate A. alternata in the greenhouse method. And disease
severity assessments were taken every 2 days beginning at 3 day until 21 day. The
experimental design was a completely randomized design (CRD) with three
replications and seven genotypes, which had been infected with the two leaves
of each iteration. In vitro selection of fungal isolates of A.
alternata, chlorotic and necrotic symptoms began 1 to 2 days after
inoculation, but the assessment of greenhouse symptoms appeared 6-10 days after
inoculation. The area under the disease progress curve values were presented by
analysis of variance (ANOVA), and they were compared using Duncan’s test (a =
0.01%).
In both methods,
there was a significant difference between the potato genotypes (P < 0.01).
For In vitro selection and evaluation greenhouse, the results
showed that Casmos was the most sensitive cultivar and Marfona was the most
tolerance cultivar.
Article by Hamid
Reza Mirkarimi, et al, from Iran.
Full access: http://mrw.so/2eWtzH
Image by Jenn Brazil, from Flickr-cc.
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