Reaction of melon accessions to crater rot and resistance inheritance

Abstract

The aims of the present study were to assess the reaction of melon accessions to crater rot, caused by Myrothecium roridum, and study the inheritance of resistance. In the first experiment, 30 melon accessions from northeastern Brazil were assessed in a randomized block design with two replicates. Each plot was formed by a row of 12 plants, from which three fruits were sampled and used for inoculation. Each fruit was inoculated at four equidistant sites on the surface. Ten wounds were made at each site to an approximate depth of 3.0 mm, to which 0.05 mL of conidial suspension was placed at a concentration of 10 6 spores mL -1 of sterilized distilled water with the aid of a pipette. The fruits were placed on Petri dishes and enveloped in polyethylene bags containing hydrophilic cotton, both of which were moistened with sterilized distilled water. Five days after inoculation, the injured area (in mm 2 ) was assessed. Accessions A-9, A-14 and A-30 were resistant to the CMM-609 isolate of M. roridum. In the second experiment, the parents AF-682 and UFERSA-05 were used as standards of susceptibility and resistance, respectively. From these plants, generations F 1 , F 2 , RC 11 and RC 12 were obtained. The six populations were grown under field conditions in a randomized block design. Resistance to crater rot on the melon fruits exhibited complex inheritance, with six loci and the involvement of additive and dominance effects.

New sources of resistance to Myrothecium roridum and Podosphaeria xanthii in yellow melon

“…The information available for M. roridum in melon was obtained through fruit and leaf observation. Nascimento et al (2012) observed a heritability estimate of 65.82% for the reaction to rot crater, while Kuti et al (1987) found coefficients below 30% on leaf reaction. In theory, heritability coefficients depend exclusively on the population and environmental conditions (Aragão et al 2015).…”

“…This fact is an indication that genetic control seems to be complex. Nascimento et al (2012) found that the genetic control polygenic and oligogenic for fruit, or polygenic for leaves. However, further studies must be carried out to confirm such hypothesis.…”

Pathogenicity of novel Monosporascus species in accessions of four melon botanical groups

“…In addition, it has lower RI DM (Table 2). The accession A-16 has fruits with high mesocarp firmness, high titratable acidity, low content of soluble solids (Dantas et al 2015) and resistance to Myrothecium roridum (Nascimento et al 2012). This accession belongs to the acidulus botanical group, very usual in India, which has provided many sources of resistance to pathogens such as fungi, viruses and insects (Dhillon et al 2012).…”

“…Matsum. & Nakai) (Iglesias et al 2000a; Sales Júnior et al 2012; Al-Mawaali et al 2013; Yan et al 2016; Markakis et al 2018; Negreiros et al 2019).…”