Obtaining pepper F2:3 lines with resistance to the bacterial spot using the pedigree method

Abstract

The economic importance of sweet pepper is rising in Brazil and abroad. Nevertheless, diseases, such as the bacterial spot (Xanthomonas campestris pv. vesicatoria or Xanthomonas euvesicatoria) jeopardize its yield. An efficient method for controlling the disease is the use of resistant varieties. The objective of this work was to select sweet pepper genotypes with resistance to the bacterial spot on a segregating population (Capsicum annum accessions UENF 1421, susceptible, x UENF 1381, resistant), advanced using the pedigree method. Three selection procedures, " selection between and within families" , " mass selection" , and " combined selection" were compared. Fifty-six F2:3 families (40 plants per family) were planted in the field, without replication. Ten plants of each genitor were used as controls in each line, between families. Plants were inoculated (isolate ENA 4135) 42 days after transplanting and leaves were collected and digitalized three weeks after. Images were analyzed to obtain the percentage of leaf tissue damaged (RMB%) and leaf damaged area (RMBcm²). Since similar results were achieved using either RMB% or RMBcm², we suggest using RMB% in further studies instead of RMBcm², which values remain close to zero. Eleven lines had promising results when selection within and among F2:3 families was used (genetic gains = 40%). Considering mass selection, eleven individuals (three lines), were selected (genetic gains = 28%). Based on combined selection, three lines (11 individuals within the lines) were selected (genetic gains = 266%). There were three lines (105, 475, and 517) in common between selection among and within families and mass selection, and another three (111, 260, and 313), between selection among and within families and combined selection. Combined selection was 6.6 (RMB%) and 6.5 (RMBcm²) times more efficient than selection among and between families, and 9.6 (RMB%) and 9.5 (RMBcm²) times more efficient than mass selection.

Research Article Multiple genetic resistances in Capsicum spp.

“…By the results obtained for the AUDPC-BS six genotypes of C. annuum were resistant, one is the resistance pattern (UENF 1381), as already expected, three genotypes ('UENF Campista', 'UENF Carioquinha', and 'UENF Carioca') were resistant since they are cultivars developed from crosses involving UENF 1381 (Riva-Souza et al, 2007. Three recessive genes confer genetic control of BS resistance (Riva et al, 2004b); therefore, the studied cultivars are homozygous for this trait.…”

“…The first contained 1.0 x 10 8 CFU/mL, being in a hypersensitivity reaction (HR); the second, with 1.0 x 10 5 CFU/mL, was used in a quantitative resistance evaluation. As inoculum, we used an ENA 4135 isolate, which was previously characterized as X. euvesicatoria by Riva-Souza et al (2007), as classification proposed by Jones et al (2004) and reported by Potnis et al (2015). Both concentrations were inoculated on the same day in two distinct leaves of the same plant, duly identified.…”

“…Starting from this concentration, a serial dilution was performed to reach a concentration of 1.0 x 10 5 CFU/mL. Plants were inoculated 15 days after being transplanted by infiltration of bacterial suspension onto the leaf abaxial surface throughout an area of nearly 1.0 cm 2 , using a syringe and hypodermic needles (Riva-Souza et al, 2007;Pimenta et al, 2016).…”

Resistência à mancha-bacteriana e características agronômicas de linhas recombinadas de Capsicum annuum L.

“…O acesso UENF 1381 é uma pimenta que vem sendo utilizado como fonte de resistência à mancha-bacteriana no programa de melhoramento desenvolvido pela UENF. As linhas foram obtidas pelo método Single Seed Descent (SSD) e selecionadas para a resistência à mancha-bacteriana e outros atributos agronômicos por Riva et al (2004a) e Riva-Souza et al (2007;. Também foram avaliados o genitor UENF 1381, a cultivar Early California Wonder (ECW), utilizada como testemunha para suscetibilidade à mancha-bacteriana e uma cultivar atualmente comercializada junto aos produtores ('Itapuã 501').…”

“…Vários autores citam o uso de cultivares resistentes como o processo mais eficaz no controle de doenças em plantas (Quezado-Duval & Camargo, 2004;Silva-Lobo et al, 2005;Riva-Souza et al, 2007. A resistência genética é desejada, por reduzir a contaminação do ambiente e dos alimentos pelo uso de pesticidas .…”