Extending the knowledge on the histological patterns of leaf galls induced by Ditylenchus gallaeformans (Nematoda) on Miconia (Melastomataceae) hosts

Abstract

Plant-parasitic nematodes can manipulate their host-plant tissues to induce the neoformation of structures called “galls”. These structures confer protection for the nematode colonies against biotic and abiotic factors, as well as guarantee food supplies, while the feeding stimulus lasts. Ditylenchus gallaeformans induces galls on leaves of several Miconia species (Melastomataceae) of the Brazilian Cerrado. These galls were previously described as occurring on leaves and inflorescences of Miconia albicans and M. ibaguensis, with the outstanding feature of indeterminate growth conferred by the totipotent capacity of the nutritive cells. Currently, we describe the structural profile of the galls induced by D. gallaeformans on leaves of M. corallina and M. lacunosa and compared these galls to those induced on M. albicans and M. ibaguensis by cluster and principal component (PCA) analyses. As expected, the galls induced on the four Miconia species share similar anatomical features, including the indeterminate growth potential. Besides the commonalities between the four galls, the differences in indumentum and size were determined by gall induction sites and host plant potentialities. Also, other traits of each host plant species supported the separation between M. lacunosa in the PCA (PC1+PC2 = 84.5% of explained variance) and the clustering of the other three Miconia species, which looks like to coincide with the phylogeny of the host plants. The anatomical features of these galls also indicated adaptations to the maintenance of the homeostasis in the gall microenvironment and the protection against stressful conditions of the Brazilian Cerrado.