Marcadores RAPD para detecção de resistência à ferrugem-asiática-da-soja

Abstract

Resumo -Os objetivos deste trabalho foram confi rmar a herança da resistência da PI 459025 (Rpp4) à ferrugemasiática-da-soja e identifi car marcadores moleculares do tipo RAPD, ligados a este gene de resistência, em populações de soja. Pelo cruzamento dos genitores contrastantes PI 459025 x Coodetec 208 obteve-se uma população, cujas populações das gerações F 2 e F 2:3 foram artifi cialmente infectadas e avaliadas quanto à reação ao fungo Phakopsora pachyrhizi, pelo tipo de lesão (RB -resistente e TAN -suscetível). Com os resultados da avaliação fenotípica, dois "bulks" foram obtidos com DNA de plantas homozigóticas resistentes e suscetíveis, respectivamente, pela análise de "bulks" segregantes. De 600 iniciadores RAPD aleatórios, foram identifi cados três com fragmentos polimórfi cos entre os "bulks" e parentais contrastantes quanto à resistência. Pela análise do qui-quadrado, confi rmaram-se: a herança monogênica, com dominância completa quanto à resistência ao patógeno, e a segregação 3:1 para a presença de banda dos três marcadores. Os três marcadores são ligados respectivamente a 5,1, 6,3 e 14,7 cM de distância do loco de resistência, em fase de repulsão no grupo de ligação G, o que foi confi rmado pela utilização do marcador microssatélite Satt288. Estes marcadores são promissores na seleção assistida para resistência à ferrugem-asiática-da-soja.Termos para indexação: Glycine max, Phakopsora pachyrhizi, marcadores moleculares, seleção assistida. RAPD markers for detection soybean rust resistanceAbstract -The objectives of this work were to confi rm the PI 459025 inheritance of resistance (Rpp4) to Asian soybean rust pathogen and to detect RAPD markers linked to this resistance gene in soybean populations. Through the cross of the distint parental lines PI 459025 x Coodetec 208, a population was obtained, whose F 2 and F 2:3 generations had their populations artifi cially infected and evaluated for the reaction to Phakopsora pachyrhizi, by lesion type classifi cation (RB -resistant and TAN -susceptible). Using the phenotypic results, the bulked segregant analysis was performed and two DNA bulks were obtained from homozygous resistant and homozygous susceptible plants, respectively. Out of the 600 random RAPD primers analyzed, three were identifi ed as polymorphic fragments related to resistance, between contrasting bulks and parents. Through chi-square test, confi rmations were obtained for the monogenic inheritance, with complete dominance segregation for resistance to the pathogen, and the 3:1 segregation of band presence for the markers. The three markers are linked to the resistance locus, in repulsion phase, at 5.1, 6.3 and 14.7 cM from it, in the linkage group G, which was confi rmed by using the microsatellite marker Satt288. These makers are promising in assisted selection for Asian soybean rust resistance.Index terms: Glycine max, Phakopsora pachyrhizi, molecular markers, assisted selection. IntroduçãoA expansão do cultivo da soja, observada desde sua introdução comercial no Brasil na década de 70,...

Inheritance and genetic mapping of resistance to Asian soybean rust in cultivar TMG 803

“…Thus, considering (p = 0.05), both hypotheses of segregation were considered true. This confirms results reported in other studies, where monogenic inheritance with complete dominance was observed in PI 200492 (Rpp1) (Hyten et al 2007), in PI 230970 (Rpp2) (Silva et al 2008) and in PI 459025 (Rpp4) (Silva et al 2008, Costa et al 2008. Similarly, a 13:3 ratio was observed in several segregating F 2 soybean populations resistant to SR, considering the segregation pattern of the RB and TAN reactions (Pierozzi et al 2008).…”

Estimates of genetic parameters in F4 F5 soybean populations resistant to Asian soybean rust

“…The genotypes used were developed from crosses between parents, which were resistant (R) and susceptible (S) to Asian soybean rust: PI 200526 Shiranui (R) x COODETEC 205 (S) and PI 200456 (R) x MG/BR-46 (Conquista) (S) (Costa, 2008). The parents resistant to the pathogen correspond to the introduction of exotic plants (PI's) and the susceptible plants are cultivars already adapted to Brazilian conditions, with a good agronomic performance for grain-producing characters.…”

Molecular Markers: Assisted Selection in Soybeans

“…DNA from plants of each group was analyzed individually and the band found previously was confirmed (Figure 1). Recently Costa et al (2008) identified RAPD markers linked to genes conferring resistance to rust caused by Phakopsora pachyrhizi. The authors applied the methodology BSA (ten plants in each group) and related markers: OPBB16 650 , OPAK04 800 OPR04 850 and distant to 5.1 cM and 6.3 cM and 14.7 cM, respectively, the locus of resistance Rpp4.…”