Utilização de multilinhas dinâmicas para o manejo da antracnose do sorgo

Abstract

Resumo -O objetivo deste trabalho foi avaliar a eficiência do uso de multilinhas dinâmicas, por meio de misturas genéticas em populações de híbridos triplos, no manejo da antracnose do sorgo, causada pelo fungo Colletotrichum sublineolum. Foram obtidos 18 híbridos triplos a partir de sete linhagens que continham genes distintos para resistência à doença. Os 25 genótipos de híbridos e linhagens foram avaliados em campo. Verificou-se, em alguns híbridos, grau de resistência superior ao observado para a linhagem mais resistente utilizada nos cruzamentos, o que indica efeito aditivo dos genes de resistência das diferentes linhagens na composição da resistência final dos híbridos. O uso das multilinhas dinâmicas reduziu a intensidade da doença no campo e aumentou a produtividade. Essa estratégia torna possível a utilização de linhagens que apresentam características agronômicas desejáveis, mas são suscetíveis à antracnose.Termos para indexação: Colletotrichum sublineolum, Sorghum bicolor, híbridos triplos, piramidação de genes, resistência dilatória, variabilidade genética. Use of dynamic multilines for the management of sorghum anthracnoseAbstract -The objective of this work was to evaluate the efficiency of dynamic multilines, using genetic mixing in populations of three-way hybrids, in the management of sorghum anthracnose, caused by the fungus Colletotrichum sublineolum. Eighteen three-way hybrids were obtained from seven different lines containing genes for resistance to the disease. The 25 genotypes of hybrids and lines were evaluated in field conditions. In some hybrids, a higher resistance level was observed when compared to that of the more resistant line used in the crosses, indicating an additive effect of the resistance genes of the different lineages in the composition of the final resistance of hybrids. The use of dynamic multilines reduced the disease intensity in field and increased productivity. This strategy makes it possible to use lineages that have desirable agronomic characteristics, but are susceptible to anthracnose.

Genotype rotation for leaf anthracnose disease management in sorghum

“…After flowering, the plant needs the maximum of green and healthy leaf area to produce photoassimilates that will be destined to grain filling. Thus, the lower severity of the disease during this phase will ensure the productive potential of the plant favoring the grain filling to complete (Costa et al, 2010). The lowest disease severity observed in the rotation is probably due to a reduced amount of primary inoculum in the crop area as a result of selection pressures exerted by the resistant genotypes against the pathogen population (Costa et al, 2010).…”

“…Resistance gene-based strategies available for plant disease management include mixture cultivation or multiline variety, rotational cultivation of genotypes, gene pyramiding and gene rotation (Wolfe, 1985;Pedersen and Leath, 1988;Ngugi et al, 2001;Casela and Guimarães, 2005;Costa et al, 2012). The exploitation of vertical resistance requires continuous monitoring of plant resistance and the virulence structure of the populations of the pathogen (Crill et al, 1982).…”

Quantification of yield losses caused by leaf anthracnose on sorghum in Brazil

“…The use of resistant cultivars (Casela, Frederiksen, & Ferreira, ; Casela & Frederiksen, ; Moore, Ditmore, & Tebeest, ; Chala et al., ; Costa et al., ) and fungicide application (Costa et al., ; Cota, Costa, Silva, & Lanza, ; Resende, Rodrigues, Costa, & Silva, ) are the primary measures for controlling anthracnose in sorghum. Besides these, mixture of genotypes (Guimarães et al., ; Silva et al., ), rotation of cultivars (Silva et al., ), dynamic multiline population approach (Costa, Zambolim, Silva, Cota, & Casela, ) and pyramids of genes (Casela et al., ) are additional strategies to increase the durability of sorghum resistance to C . sublineolum .…”

Pathotypes of Colletotrichum sublineolum in Response to Sorghum Populations with Different Levels of Genetic Diversity in Sete Lagoas‐MG

“…The letters A, B and R following the names of the lines are part of the encoding method used to define the role of the line in the crosses: A (male‐sterile cytoplasm), B (fertility cytoplasm but not restorer of fertility) and R (fertile restorer) (Costa et al. ). To simulate a realistic field situation as closely as possible, the six host populations were planted in four‐row plots, 10 m long, 0.9 m apart, with 0.2 m between plants within rows, resulting in a population of 200 plants per plot.…”

“…Thus, plants with three levels of genetic diversity were used: pure stands of the lines CMSXS142 and CMSXS210; dynamic multiline population of three-way hybrids: TWH1 [(CMSXS210 A 9 CMSXS112 B) 9 CMSXS182 R], TWH2 [(CMSXS210 A 9 CMSXS215 B) 9 CMSXS182 R] and TWH3 [(CMSXS112 A 9 CMSXS215 B) 9 CMSXS182 R]; a physical mixture of all three-way hybrids (PMH). The letters A, B and R following the names of the lines are part of the encoding method used to define the role of the line in the crosses: A (male-sterile cytoplasm), B (fertility cytoplasm but not restorer of fertility) and R (fertile restorer) (Costa et al 2012). To simulate a realistic field situation as closely as possible, the six host populations were planted in four-row plots, 10 m long, 0.9 m apart, with 0.2 m between plants within rows, resulting in a population of 200 plants per plot.…”