Identificação de marcadores moleculares do tipo trap (traget region amplification polymorphism) em híbridos de Poncirus Trifoliata e Citrus Sunki.

Abstract

The Brazilian citrus industry faces serious problems and losses due to the large number of diseases caused by pathogens. Considering that the genetic resistance is an important component of integrated strategies to control plant diseases, because it is efficient, low cost to the producer, beneficia] to man and the environment, the citrus breeding programs seek to increase productivity by using genetic strategies for disease control. Durante o desenvolvimento de novas variedades, melhoristas têm incorporado a seleção assistida por marcadores, na detecção de genes que estejam associados com a resistência a doença. A new and efficient system of molecular markers, TRAP (Target Region Amplification Polymorphism) based on PCR, using bioinformatics tools and information database of ESTs to generate polymorphic markers around the possible sequences of candidate genes. In this sense, the largest database of expressed genome of citrus in the world, CitEST generated in Brazil, represents & powerful tool to help the citrus breeding program, since it has all the genes expressed in citrus species considered (ll species) and genotypes under contrasting conditions, such as resistant versus susceptible induced versus not induced by pathogens. In this context, this paper describes the identification of markers amplified by primers TRAPS fixed, designed from genes associated with resistance to CTV (citrus tristeza virus), using DNA from individuals of the Fl progeny from the crossing of Poncirus trifoliata with Sunki (Citrus sunki), parental susceptible and resistant to disease, respectively. Of a total of 08 combinations of primers abritrário / fixed tested 02 combinations showed polymorphism, generating a total of 04 marks and an average number of markers per pair of primer on the value of 2. The Chi—square applied to individual markers traps, revealed that 100% of the identified markers segregate in Mendelian lzl ratio. Therefore, these markers may be placed on the linkage map of P. trifoliata. These markers may also be used in the genotyping of all individuals of that population Fl.