In Vitro Screening of Potato Genotypes for Resistance to Common Scab Using Thaxtomin A

초록

Thaxtomin A is a bio-toxin produced by Streptomyces scabies and is thought to be responsible for visible tuber symptoms associated with the common scab disease. It was hypothesized that response of in vitro plantlets to the toxin may be related to tuber reaction in the field. A population of 100 genotypes originating from a resistant x susceptible cross was evaluated for both in-vitro thaxtomin response and field occurrence of common scab on the tubers. The shoot height of plantlets grown on the medium containing thaxtomin A was used as a measure of the tolerance of each genotype. The surface area infected index (SAII) of each genotype was measured and used as gauge of resistance level of each genotype in the field. The correlation coefficient between in vitro shoot height of plantlets, grown on media containing 1.0 mg l-1 of thaxtomin A, and SAII of each genotype was highly significant (r=0.656). in vitro screening of potato germplasm using thaxtomin shows promise as a method to select for resistance to common scab.

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