Validação de marcadores moleculares associados à resistência à ferrugem marrom em cana-de-açúcar

Abstract

A ferrugem marrom causada pelo fungo Puccinia melanocephala é uma importante doença em cana-de-açúcar (Saccharum spp.) e está presente em praticamente todas as áreas de cultivo. Um gene de efeito maior, Bru1, foi descrito como fonte de resistência durável da cana-de-açúcar contra isolados de P. melanocephala. O objetivo deste estudo foi avaliar a eficiência de dois marcadores moleculares fortemente associados ao gene Bru1, R12H16 e 9O20-F4-RsaI, para predição da resistência genética à ferrugem marrom em variedades de cana-de-açúcar. ABSTRACTBrown rust caused by the fungus Puccinia melanocephala is an important disease affecting sugarcane (Saccharum spp.) and is present in almost all growing areas. A major effect gene, Bru1, was described as a durable resistance source in sugarcane against isolates of P. melanocephala. The aim of this study was to evaluate the efficiency of two molecular markers strongly associated with Bru1 gene, R12H16 and 9O20-F4-RsaI, for prediction of genetic resistance to brown rust in sugarcane varieties. Thus, this study included 14 RB varieties, developed by RIDESA (Interuniversity Network for the Development of the Sugarcane Industry), which were among the 10 most cultivated varieties in the central-south region of Brazil in the period of 1974-2015. To evaluate the disease in the field an experiment was conducted in randomized blocks with four replicates. The severity of Barreto, F.Z.; Balsalobre, T.W.A. Chapola, R.G.; Hoffmann, H.P.; Carneiro, M.S. Validation of molecular markers associated with brown rust resistance in sugarcane. Summa Phytopathologica, v.43, n.1, p.36-40, 2017. brown rust was quantified according to a diagrammatic scale ranging from 1 (most resistant) to 9 (most susceptible), and the obtained data were analyzed by using a generalized linear mixed model (GLMM). Concomitantly, total DNA was extracted from the 14 varieties, followed by amplification of the molecular markers, which were classified into haplotypes. Out of the total varieties, 12 had no symptoms of the disease and showed 99.35% probability of being resistant according to analysis via GLMM; among them, 91.66% were haplotype 1, i.e., had the presence of both markers associated with Bru1 gene. Therefore, we can conclude that the molecular markers R12H16 and 9O20-F4-RsaI were highly efficient in predicting resistant phenotypes and that Bru1 gene is probably the main source of sugarcane resistance to brown rust in commercial fields in Brazil.Keywords: Saccharum spp., breeding, Puccinia melanocephala, Bru1, disease resistance.A cana-de-açúcar (Saccharum spp.) está entre as mais importantes espécies cultivadas, principalmente para produção de açúcar e bioetanol (1). O Brasil é atualmente o país com a maior produção de cana-deaçúcar com mais de nove milhões de hectares cultivados e produtividade estimada em 76.909 kg ha -1 na safra 2015/16 (1, 2). A cana-de-açúcar é uma gramínea semi-perene com propagação vegetativa, sendo que os programas de melhoramento genético têm concentrado esforços para o desenvolviment...

Selection of families obtained from caryopsis in a polyploid species (Saccharum spp.) using multicategory model

“…Modern cultivars of sugarcane are highly polyploid, derived from interspeci c hybrids between S. o cinarum (2n = 80) and its wild relative S. spontaneum (2n = . The complexity of the sugarcane genome is due to its high number of chromosomes, ranging from 100 to 130, its genome size of approximately 10 Gb, and the occurrence of aneuploidy, with a variable number of chromosomes in each homology group (Andru et al, 2011;Barreto et al, 2017;Metcalfe et al, 2015).…”

“…The narrow genetic base of current sugarcane cultivars has been justi ed by the fact that they are derived from fewer than 20 genotypes from breeding programs in Java, India (Landell and Bressiani 2008). On the other hand,Barreto et al (2017) justi es the narrow genetic base as a result of successive backcrosses to insert characteristics such as disease resistance.…”

Research Article Resistance to orange rust associated with the G1 molecular marker in parents of Brazilian RB sugarcane varieties

“…In addition, it can be used to indicate potential parents for future crosses and establish resistance alleles (Fier et al, 2020). Genotype classification by molecular techniques in sugarcane has been used for resistance to brown rust (Puccinia melanocephala) (Barreto et al, 2017).…”

Prospecting brown rust of sugarcane in São Paulo-Brazil under climate change scenarios

“…Geographic and temporal distribution maps allow assessing the impact of favorability for the occurrence of the disease, showing differences among producing regions in Brazil in the future scenarios (Angelotti et al, 2017). Found in Brazil in 1986(Takeshi and Rago, 2016, brown rust, caused by Puccinia melanocephala, is an important disease of sugarcane and is present in practically all growing areas around the world (Barreto et al, 2017); however, Brazil still lacks studies on the favorability of this disease when future climatic scenarios are taking into account. The aim of this study was to prospect the geographic distribution of sugarcane brown rust (Puccinia melanocephala) considering average temperature and relative humidity in the main producing region of the state of São Paulo.…”