Comparative Analysis of Phenotypic and Molecular Data on Response to Main Pear Diseases and Pest Attack in a Germplasm Collection

Abstract

The pear is an important fruit tree in temperate areas, but due to its sensitivity, fruit yield and quality are often affected by disease and pest attacks. Pear genotypes from a germplasm collection comprising 13 Pyrus species, 17 Romanian varieties, and 50 non-Romanian varieties from a worldwide assortment were investigated in this study. Throughout four years, response to attack of the principal pathogens and pests was investigated phenotypically under natural conditions of infection and infestation. SSR markers were used to analyze the genetic diversity of the genotypes. A standardized method for the evaluation of responses to biotic stressors was proposed, which highlighted significant differences between genotypes. The species and varieties with the lowest degrees of attack (DA%), calculated based on the frequency and intensity of attack, were identified for pear scab (Venturia pyrina), septoria (Septoria pyricola), fire blight (Erwinia amylovora), and psyllids (Psylla sp.). These accessions could provide valuable sources of genes of interest to develop resistant varieties in new pear breeding programs. By combining phenotypic and molecular analyses, significant information was obtained that can be exploited to generate high variability for selection through artificial hybridization by harnessing accessions with complementary molecular fingerprints and high genetic distances.

Field trial of new Bt-base bioinsecticide formula, Bashield®, for controlling Spodoptera frugiperda J.E. Smith on maize

“…Parasporal crystals of B. thuringiensis will enter through the insect's digestive tract, these protein crystals will become δ-endotoxin protein or protoxin when activated by the alkaline environment in the digestive tract, then the insect protease enzyme will activate the protoxin to become a toxin and bind specifically to the receptor in the tract. Digestion, cry toxin which attaches to the peritropic membrane is what can cause death in insects because it is injurious and causes cytoplasmic leakage [23]. Based on the recorded larval mortality data, it is known that the concentration estimation value is based on regression analysis with the equation Y = a + bX with a and b values of -0.846 and 1.319 respectively with an R 2 value of 0.951.…”

“…The intensity scale uses Davis scale measurements [22]. The determination of the intensity of S. frugiperda attacks is calculated using the equation 3 [7], [23].…”