Validation of the G1 Molecular Marker Associated with Resistance to Orange Rust in Brazilian Sugarcane Genotypes
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RESEARCH ARTICLE
Validation of the G1 Molecular Marker Associated with Resistance to Orange Rust in Brazilian Sugarcane Genotypes Lı´via Maria Lemos Hoepers1 • Gabriel Koch1 • Mayara Catherine Candido Silva1 Lucimeris Ruaro1 • Renata Faier Calegario1 • Joa˜o Carlos Bespalhok Filho1 • Ricardo Augusto de Oliveira1 • Henrique da Silva Silveira Duarte1
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Received: 20 April 2020 / Accepted: 16 September 2020 Ó Society for Sugar Research & Promotion 2020
Abstract Orange rust, caused by the fungus Puccinia kuehnii, is an important disease of sugarcane (Saccharum sp.). A molecular marker (G1) was developed to identify the resistance of sugarcane to orange rust. The aim of the present study was to validate the molecular marker G1 in the detection of resistance to orange rust in Brazilian sugarcane genotypes. 80 genotypes were analyzed by PCR, being classified according to the presence or absence of the marker. For field evaluation of orange rust resistance, a randomized block experiment was conducted, with the same 80 genotypes using four replications. Artificial inoculation was performed in the leaf whorl, with an evaluation made at 30 days after inoculation, using a scale from zero (without symptoms) to four (more than five pustules with sporulation), in which cultivars with an average score between zero and two were classified as resistant, and a score greater than two, susceptible. Of the 17 genotypes classified as resistant through the field test, 9 did not present the respective band. Of the 63 susceptible genotypes, 27 had the band relative to the molecular marker G1. The selection accuracy of G1 marker (the efficiency of predicting resistant phenotype) was 22.86%. The Phi correlation coefficient (/) was calculated, through which it was observed that the variables are independent, with no statistically significant correlation between them. The results indicate that the G1 marker had a low efficiency to predict the resistance to orange rust in clones under
& Henrique da Silva Silveira Duarte [email protected] 1
Departamento de Fitotecnia e Fitossanidade, Programa de Po´s-graduac¸a˜o em Agronomia, Universidade Federal do Parana´, Rua dos Funciona´rios, 1540, Cabral, Curitiba, Parana´ CEP 80035-050, Brazil
selection in a Brazilian breeding program and Brazilian commercial cultivars of sugarcane. Keywords Saccharum spp. Puccinia kuehnii Marker-assisted selection MAS
Introduction Sugarcane is one of the most important crops in Brazil, and the country is currently the world’s largest producer, with an estimated production of 747 million tons in the 2018 harvest, followed by India, China and Thailand (FAOSTAT 2020). Brazilian production corresponds to approximately 40% of the world total, and the country stands out with the largest planted area (approximately 10 million hectares), and an average productivity of 75.78 ton ha-1 (CONAB 2019). The sugarcane production is influenced by genetic characteristics of cultivars, climate, availability of nutrients, attack by pests and incidence of diseases, among oth
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