Random amplified polymorphic DNA markers tightly linked to a gene for resistance to white pine blister rust in sugar pine.

Abstract

GeneticsRandom amplified polymorphic DNA markers tightly linked to a gene for resistance to white pine blister rust in sugar pine ( ABSTRACTWe have genetically mapped a gene for resistance to white pine blister rust (Cronartium ribicola Fisch.) in sugar pine (Pinus lambertiana Dougl.) by using an approach which relies on three factors: (i) the ability to assay for genetic markers in the haploid stage of the host's life cycle, using megagametophyte seed tissue; (ii) a simple and clearly defined pathosystem; and (iii) the use of random amplified polymorphic DNA (RAPD) markers that can be quickly and efficiently evaluated. Resistance to white pine blister rust in sugar pine is known to be controlled by a single dominant gene (R). Maternal segregation ofR and dominant RAPD markers were scored simultaneously following collection of megagametophytes for DNA assays and seedling inoculation with C. ribicola. Bulked samples of haploid megagametophyte DNA from resistant and susceptible offspring of segregating full-sib and half-sib families were used to evaluate 800 random decanucleotide primers. Ten loci linked with the gene for resistance to white pine blister rust were identified and segregation data were obtained from five families. Six of the linked markers were within 5 centimorgans of the gene, and one marker was 0.9 centimorgan from R. These and other markers derived by this approach may provide starting points for map-based cloning of this important gene.

Genetic and physical mapping of Melampsora rust resistance genes in Populus and characterization of linkage disequilibrium and flanking genomic sequence

“…in poplar ( Hsiang & Van Der Kamp, 1985;Cervera et al ., 1996;Lefevre et al ., 1998). Molecular markers have been identified that are tightly linked to several disease-resistance loci ( Devey et al ., 1995;Wilcox et al ., 1996;Lefevre et al ., 1998;Stirling et al ., 2001), but resistance genes have yet to be cloned and functionally characterized for a forest tree.…”

Análise da herança da resistência a Puccinia psidii em progênies de híbridos interespecíficos de eucalipto avaliadas sob condições naturais de infecção

“…Variação em resistência a P. psidii também foi relatada em outros gêneros de mirtáceas provenientes de várias regiões da Austrália, indicando que não só o gênero Eucalyptus possui genes de resistência a este fungo (Zauza, 2007). Em patossistemas florestais com pouco histórico coevolutivo e onde existe resistência monogênica, como pinus x ferrugem e populus x ferrugem, a resistência é conferida por genes de resistência a patógenos similares encontrados no local de origem do hospedeiro (Devey et al, 1995;Newcombe et al, 1996) e exemplos de um mesmo gene conferindo resistência a diferentes patógenos (Cooley et al, 2000), a várias raças de um patógeno (Buschges et al, 1997) ou mesmo controlando a expressão de diferentes características tem sido encontrados na literatura (Llorente et al, 2005). Estes patógenos devem codificar proteínas que possuem certas regiões em comum, que possivelmente desempenham papel indispensável à sua sobrevivência, permitindo assim que a proteína de resistência do hospedeiro reconheça diferentes proteínas de avirulência do patógeno.…”

Molecular markers: their use in tree improvement

“…A major drawback of the technique is that because of the random nature of their generation, and short primer length, they cannot be easily transferred between species. An additional drawback is that of poor reliability and reproducibility, and their sensitivity to experimental conditions (Devey et al 1995).…”