Identificação de híbridos de citros resistentes à mancha-marrom-de-alternária por meio de fAFLP e testes de patogenicidade

Abstract

Resumo -O objetivo deste trabalho foi identificar híbridos, oriundos de hibridações controladas entre 'Folha Murcha' x 'Ponkan' e testá-los quanto à resistência a Alternaria alternata f. sp. citri. As plântulas foram obtidas via cultura in vitro de embriões. Utilizou-se o marcador molecular fAFLP para identificação dos híbridos e, em seguida, realizou-se o teste de patogenicidade nos híbridos com isolados de Alternaria alternata f. sp. citri, em condições de laboratório. Os pares de primers EcoRI AAG -MseI CAG e EcoRI ACC -MseI CAA foram os mais eficientes na identificação dos híbridos, os quais identificaram 48,5% de híbridos. Os híbridos F64, F108, F111, F113, F131 e F139 são potencialmente resistentes a Alternaria alternata f. sp. citri.Termos para indexação: Citrus sinensis, Citrus reticulata, melhoramento genético, biotecnologia vegetal, marcador molecular. Alternaria brown spot resistant citrus hybrid identification by means of fAFLP and pathogenicity testsAbstract -The objective of this work was to identify hybrids obtained from controlled crossings between 'Folha Murcha' x 'Ponkan', and to check their resistance to Alternaria alternata f. sp. citri. The seedlings were obtained by in vitro embryo culture. The fAFLP marker technique was used to identify the hybrids, then laboratory pathogenicity test of the hybrids was accomplished with Alternaria alternata f. sp. citri isolates. The pairs of primers EcoRI AAG -Msel CAG and EcoRI ACC -Msel CAA were the most efficient for hybrids identification, and distinguished 48.5% of hybrids. Hybrids F64, F108, F111, F113, F131 and F139 showed potential resistance to the Alternaria alternata f. sp. citri.

Comparison between diploid and tetraploid citrus rootstocks: morphological characterization and growth evaluation

“…The rootstock is important in establishing a good quality orchard, since it influences several characteristics of the plant and fruit (Davies and Albrigo, 1994;Pompeu Junior, 2005;Schäfer and Dornelles, 2000), besides increasing tolerance to phytosanitary problems (Chagas et al, 2007).…”

Caracterização morfológica, determinação do número de embriões e taxa de poliembrionia em três porta-enxertos híbridos de citros

“…Em citros, o porta-enxerto exerce muitas influên-cias sobre a planta e os frutos podendo afetar mais de 20 características, dentre elas, o desenvolvimento da cultivar-copa, teor de nutrientes das folhas, produção e tamanho dos frutos, quantidade de suco, teor de sólidos solúveis totais, acidez do suco (Schäfer et al, 2001), além de tolerância a problemas fitossanitários (Chagas et al, 2007). Por esse motivo, a escolha da cultivar a ser utilizada é uma fase muito importante no planejamento do pomar, devendo ser levadas em consideração características de clima, solo, variedade-copa, manejo (Schäfer et al, 2001), bem como as moléstias que acometem a cultura na região (Passos et al, 2006).…”

Climate zoning: identifying suitable regions for the occurrence of Alternaria Brown spot in tangerine trees in Brazil

“…36 The selection and planting of resistant varieties are of great importance and interest for the development of commercial citrus production, 17,37,38 but it remains a challenge for genetic improvement because resistant cultivars do not always meet market quality requirements. 39 Alternaria brown spot requires specific climate conditions. 18,40 The optimal conditions for infection of affected plant material occur with air temperatures around 20-27 °C and ≈10-12 h of continuous leaf wetness, 41 with symptoms appearing 1-2 days postinfection.…”

“…The symptoms caused by the toxin are characterized by necrotic lesions on branches, fruits, immature green tissues or growing tissues, which can lead to extensive defoliation during periods of higher infection as a result of leaf necrosis, consequently reducing production 36 . The selection and planting of resistant varieties are of great importance and interest for the development of commercial citrus production, 17,37,38 but it remains a challenge for genetic improvement because resistant cultivars do not always meet market quality requirements 39 …”