Search for Resistance Sources to Brown Rot in Brazilian Peach Genotypes

Abstract

The brown rot caused by Monilinia fructicola is the most important disease in Prunus species in places of hot and humid climate. The development of resistant cultivars is a priority of breeding programs located in humid regions. However, very few sources of good resistance level are known in spite of all the efforts. This work aimed to evaluate the reaction of peach genotypes to M. fructicola. The study was conducted during the 2012/13 season, using a completely randomized design, with two replications of five fruit per plot. Fruit at firm maturation stage (harvest point) of 174 genotypes, including, cultivars, selections and seedlings, were selected for absence of apparent damage and/or infection. These fruits were dipped for 1 min in 70% alcohol, followed by a 5 min immersion in a 0.5% solution of NaClO. After a 10 min rest period they were washed in distilled water and placed in plastic transparent boxes (24.0 x 23.0 x 10.0 cm), lined with moistened filter paper. The inoculation was made, by deposition of a 10µL drop suspension of 25,000 conidia mL-1 of the pathogen using an inoculation syringe. Inoculated fruits were incubated at 25 ± 1°C and 75% relative humidity for 72 hours. After this period, the samples were evaluated for disease incidence (% of diseased fruits) and disease severity (average diameter of lesions and sporulation). The results were compared with the average lesion of cv. 'Bolinha', 0.9 cm (σ=0.9).

Peach and nectarine susceptibility to brown rot and protocol optimization to evaluate Monilinia fructicola sporulation

“…The genotypes located in the lower susceptibility group with lower values for both LD and LA were Conserva 947, 'Bolinha', Conserva 1600, Conserva 672, and 'Maciel' (Table 1). The cultivar Bolinha is known for having the lowest LD in several other studies performed in nonwounded fruits (Feliciano et al, 1987;Santos et al, 2012;Scariotto et al, 2015;Fu et al, 2018).…”

“…For the inoculation on wounded fruits (wound penetration of 1 mm into the fruits with the syringe tip), it was used an inoculation syringe of 100 μL coupled to a repeating dispenser 50x (Hamilton ® ). In both, wounded and non-wounded fruits, 10 μL suspention of M. fructicola (2.5 × 10 4 conidia mL -1 ) with Tween-80 ® (0.1 g L −1 ) was inoculated in the equatorial region of each fruit (Crisosto, Gradziel, Ogundiwin, Bostock, & Michailides, 2009;Martínez-García et al, 2013;Scariotto et al, 2015;Fu et al, 2018;Obi et al, 2019).…”

“…(Gell, De Cal, Torres, Usall, & Melgarejo, 2009;Sun, Gao, Liu, & Wang, 2009). The most recent literatures use other types of variables to measure this parameter, they use the area covered by sporulation, sporulation diameter, number or percentage of fruits with sporulation (Scariotto, Santos, & Raseira, 2015;Garcia-Benitez, Melgarejo, De Cal, & Fontaniella, 2016;Obi, Barriuso, Moreno, Giménez, & Gogorcena, 2017;Obi, Barriuso, Usall, & Gogorcena, 2019).…”

Breeding Peaches for Brown Rot Resistance in Embrapa

“…For the wounded inoculations (penetration of 1 mm into the fruits) a 100 µL syringe coupled to a repeating dispenser 50× (Hamilton ® ) was used. In both treatments (W and NW) 10 µL suspension of M. fructicola (2.5 × 10 4 conidia mL −1 ) and Tween-80 ® (0.1 g L −1 ) was used, followed by incubation at 23 ± 1 • C and 12 h photoperiod for three days [16,18,19,[24][25][26][27].…”

“…The Brazilian cultivar Bolinha shows higher levels of resistance in fruits than most cultivars, however, its poor fruit quality, together with problems of premature fruit fall, discourage its commercial cultivation [14][15][16][17][18].…”