Selection of melon genotypes with resistance to &lt;i&gt;Didymella bryoniae&lt;/i&gt; using a diallel approach

Lucas Da Silva Santos,Alysson Jalles Da Silva,Guilherme Matos Martins Diniz,Rafaelle Fazzi Gomes,Leila Trevisan Braz,Edgard Henrique Costa Silva

doi:10.4025/actasciagron.v41i1.42600

Selection of melon genotypes with resistance to <i>Didymella bryoniae</i> using a diallel approach

Lucas Da Silva Santos, Alysson Jalles Da Silva + Show 4 more

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https://doi.org/10.4025/actasciagron.v41i1.42600

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Abstract

The development of melon lines resistant to gummy stem blight (GSB) is an important strategy for decreasing losses caused by this disease. Thus, selecting the best parents for such a goal is essential. We evaluated the general (GCA) and specific (SCA) combining abilities of lines and accessions to guide the selection of the most promising parents to develop GSB-resistant lines. Six genotypes representing two groups (group I - susceptible: group II - resistant) were crossed in a partial diallel mating design. The genotypes were evaluated for disease expression using a rating scale from 0 (resistant) to 4 (susceptible). Estimates of GCA were negative and significant for the accessions PI 420145 and PI 482398, which can be suggested for crosses aimed at obtaining melon lines resistant to GSB. There is a reciprocal effect for the resistance of melon genotypes to Didymella bryoniae, especially when PI 482398, PI 420145, and PI 140471 are crossed with JAB-20. Such results indicate that maternal effects may be involved in the resistance to gummy stem blight.

Highlights

Gummy stem blight (GSB) is one of the most destructive diseases in cucurbits worldwide, especially for melon (Keinath, 2011; Keinath, 2015)
The splitting of treatments’ degrees of freedom (DF) allowed general combining ability (GCA) information to be obtained from each group separately
A significant effect was observed on GCA for G-I and G-II (Table 2)

Summary

Introduction

Gummy stem blight (GSB) is one of the most destructive diseases in cucurbits worldwide, especially for melon (Keinath, 2011; Keinath, 2015). In Brazil, GSB is one of the most damaging diseases in melon fields (Gasparotto, Vida, Tessmann, & Alves, 2011; Cardon et al, 2016). Its aetiologic agent is the fungus Didymella bryoniae, frequently leading to symptoms such as cankers, with gum exudation on the stem, rods and petioles, eventually leading to plant death. There are no melon cultivars on the market with resistance to D. bryoniae, due in large part to the difficulty in finding genotypes with stable resistance. Some basic requirements are knowledge of pathogen variability, reliable sources of resistant genotypes and knowledge of the mechanisms involved in host resistance

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Results

Conclusion