ABSTRACT In this study, the aim of this study was to identify the source of resistance using KASP markers developed for Rpp1 – Rpp5 and screening for resistance in field trials in F2 populations. Ten F2 soybean (Glycine max (L.) Merrill) populations derived from crosses between rust-susceptible (55I57RSF IPRO, 63I64RSF IPRO) and rust-resistant sources (PI 200492, PI 594538A, PI 587880A, PI 594723, PI 230970, PI 506764, PI 459025A and PI 200487) were evaluated. All F2 plants were individually evaluated in field conditions for ASR phenotypic reactions and classified according to sporulation level. KASP markers were developed according to assays associated with Rpp genes available at SoyBase. Based on a slight difference in map position and different phenotypic disease reactions of PI 200492, we suggest that PI 594723 carries a resistance gene Rpp1-b. The Rpp1-b gene from PI 594723 was mapped on Chr 18 in a 12.4 cM region. The PIs carrying Rpp1-b (PI 594723, PI 587880A, and 594538A) showed strong resistance to ASR compared to the lines carrying Rpp1 (PI 200492). A total of 26 KASP markers were significantly associated (P < 0.01) with ASR resistance. Among those, M1, M5, and M6 (Rpp1), M13 and M14 (Rpp2), M16, M17 and M20 (Rpp3), M25 and M26 (Rpp4), and M27 and M28 (Rpp5) have the potential to be used in marker-assisted selection strategies.

Resumo: O objetivo deste trabalho foi identificar locais-chave de teste em duas macrorregiões sojícolas no Brasil, para avaliação e seleção de linhagens de soja (Glycine max). Foram testadas 22 cultivares em 23 locais, nessas duas macrorregiões (MR1 e MR2), durante quatro anos, de 2012 a 2015. Os ensaios foram conduzidos em delineamento de blocos ao acaso, com três repetições. Todas as análises foram realizadas com uso do programa GGEbiplot. As análises efeito principal de genótipo mais interação genótipo × local + efeito principal de genótipo mais interação genótipo × ambiente e efeito genotípico vs. efeito do genótipo x ambiente foram utilizadas para identificar locais de teste, isto é, locais com alta representatividade e consistência de resultados. Chapada, no Rio Grande do Sul, e Maracaju, no Mato Grosso do Sul, foram os principais locais em MR1 e MR2, respectivamente. Estes locais foram os mais representativos e consistentes ao longo dos anos, e o efeito genotípico explicou uma alta proporção da variância fenotípica.

Abstract: The objective of this work was to identify core locations in two soybean macroregions in Brazil for the evaluation and selection of soybean (Glycine max) lineages. Twenty-two cultivars were tested in 23 locations in these two macroregions (MR1 and MR2), during four years, from 2012 to 2015. Trials were conducted in a randomized complete block design with three replicates. All analyses were performed using the GGEbiplot software. The genotype main effects plus genotype × location interaction + genotype main effects plus genotype × environment interaction and genotypic effect vs. genotype x environment effect analyses were used to identify core locations, i.e., locations with high representativeness and consistency of results. Chapada, in the state of Rio Grande do Sul, and Maracaju, in the state of Mato Grosso do Sul, were the core locations in MR1 and MR2, respectively. These locations were the most representative and consistent over the years, and the genotypic effect explained a high proportion of phenotypic variance.