Resistance to whitefly (Bemisia argentifolii) and repellency to the two-spotted spider mite (Tetranychus urticae) in tomato plant hybrids with high leaf contents of acylsugar and the Mi gene

Abstract

The aim of this study is to verify levels of resistance to whitefly (Bemisia argentifolii) and the two-spotted spider mite (Tetranychus urticae) in experimental hybrids of tomato plants with high acylsugar content and that bear the Mi allele, and to compare the levels of resistance to those pests according to the presence or absence of acylsugars and the Mi allele. Eleven genotypes were tested in assessment of resistance to whitefly: two inbred lines, TOM-760 (Mi/Mi), with high acylsugar content, and TOM-684 (Mi/Mi), with low acylsugar content; six experimental hybrids heterozygous for acylsugar contents, TEX-407 (Mi+/Mi), TEX-408 (Mi+/Mi), TEX-409 (Mi+/Mi), TEX-410 (Mi+/Mi), TEX-411 (Mi+/Mi), and TEX-412 (Mi/Mi); Santa Clara cultivar (Mi+/Mi+) with low acylsugar content; and two control hybrids with low acylsugar content, Ibiza (Mi+/Mi) and Carina (Mi+/Mi). In the test for repellency to the two-spotted spider mite, we used the same genotypes as in the whitefly resistance test, except for the Carina hybrid. Genotypes homozygous for acylsugars and Mi, heterozygous for Mi/Mi or Mi+/Mi acylsugars, and homozygous and heterozygous for Mi alone showed levels of resistance to the Bemisia argentifolii fly, in contrast with the genotype with low contents of acylsugars and Mi+/Mi+. Genotypes homozygous and heterozygous for acylsugars exhibit higher levels of repellency to the Tetranychus urticae mite than genotypes with low contents of acylsugar. The Mi gene, however, was not effective in providing resistance to the two-spotted spider mite. The effects of resistance to Bemisia argentifolii shown by the acylsugars are added to the effects of the Mi gene.