Selection of plum genotypes for resistance to leaf scald

Abstract

Plum (Prunus salicina Lindl.) cultivation is seriously compromised in Brazil due to the occurrence of leaf scald, a disease caused by the bacterium Xylella fastidiosa subsp. multiplex. The objective of this study was to evaluate plum genotypes agronomically promising for resistance to leaf scald, under natural conditions of occurrence of the disease. Ten out of 50 plum genotypes belonging to the germplasm bank of “Instituto Agronômico do Paraná (IAPAR)” were selected. Five evaluations of leaf scald severity were carried out from January to February (2017 and 2018). Polymerase chain reaction (PCR) was also performed for samples of these genotypes to determine the presence of the bacterium X. fastidiosa subsp. multiplex. The genotypes differed in relation to their susceptibility to leaf scald. PR-1095 was the most resistant genotype and did not show any leaf symptom of the disease. In contrast, genotypes PR-1126 and PR-1137 had the greatest susceptibility to the disease, showing severe scald symptoms. However, PCR revealed the presence of the bacterium even in the most resistant genotypes, indicating, for example, that PR-1095, which had no symptoms of the disease, is probably tolerant to leaf scald.

Plum leaf scald: characteristics of the causative agent,symptoms, dissemination, control and prevention

“…The Institute of Rural Development of Paraná IAPAR-EMATER (IDR-Paraná) evaluated different plum crosses and concluded that the 'PR-1095' genotype was the most resistant and did not show any foliar symptoms of the disease. However, the PCR test revealed the presence of the bacteria, indicating that the genotype is probably tolerant to leaf burning, in contrast, 'Piamontesa', 'PR 1142', 'PR 1149' and 'PR 1260' genotypes do not show symptoms in the field or presence of bacteria by PCR, showing resistance to the disease (GABARDO et al, 2020), but these new genotypes have not yet been launched. Agrios (2005) defines tolerance as the ability of plants to produce good harvest, even when infected by a pathogen.…”

“…multiplex at molecular level is difficult due to the low concentrations of bacteria in insects and asymptomatic plant tissue, and non-uniform distribution in infected plants (FRANCIS et al, 2006). Laboratory PCR (Polymerase Chain Reaction) tests have been used, complementing the observation of field symptoms (HARPER et al, 2010;GABARDO et al, 2020).…”

“…The disease is widely disseminated in the main producing regions of Brazil (PALACIO BIELSA, 2017;GABARDO et al, 2020). The phytosanitary problem caused by PLS drastically affects the productivity and longevity of plum plants, which increases production cost and reduces competitiveness in relation to imported fruits (CASTRO, 2010).…”

Characterization of a Florida plum introduction (USA) in Southern Brazil

“…Few plum cultivars are available to rural producers in Brazil (MARTInAZZO et al, 2013;BAUCHROWITZ et al, 2019;GABARDO et al, 2020). Suppose there is a need for breeding programs to launch new options (DALBÓ et al, 2018;GABARDO et al, 2021).…”