Callose Reaction Induced in Melon Leaves by Feeding of Melon Aphid, Aphis gossypii GLOVER, as Possible Aphid-Resistant Factor.

Abstract

The callose reaction in leaves induced by feeding of the melon aphid, Aphis gossypii GLOVER, in aphid-resistant and susceptible melons, Cucumis melo L., was studied using the aniline-blue fluorescent-staining technique. Six or 24 h after release of ten aphids, many more callose-deposition sites were found in the leaf veins of the aphid-resistant variety 'PMAR No. 5' than in four susceptible melon varieties. When the callose reaction induced by the aphid probing was analyzed individually, aphids often stopped probing aphid-resistant melons within 20 min, but did not stop on susceptible varieties. There was no clear varietal difference between the length of the stylet sheath and the reached tissues, but in aphid-resistant melons, a large amount of callose was observed around most stylet sheaths; no or only small amounts of callose was detected in susceptible varieties. These results suggest that the callose reaction in leaves plays an important role in the aphid-resistant melon variety.