Development of a qPCR for Leifsonia xyli subsp. xyli and quantification of the effects of heat treatment of sugarcane cuttings on Lxx

The main control practice of Leifsonia xyli subsp. xyli (Lxx) in sugarcane is to heat-treat cane cuttings used as planting material in an attempt to eradicate the bacterium. A real time quantitative PCR (qPCR) protocol specific for Lxx was developed to assess the effectiveness of this practice. Primers were designed from the sequence of an Lxx-specific gene and detected as few as 10−5 ng of Lxx DNA in 100 ng of plant DNA. Two experiments were conducted to quantify Lxx titers in plants of the varieties SP80-3280 and SP70-3370 originated from cuttings treated or not by immersion in hot water at 52 °C for 30 min. In the first experiment, cuttings were collected from plant canes with low Lxx titers whereas in the second they were collected from first-ratoon canes with higher titers. Lxx was quantified in leaves by qPCR 90 days after planting and was detected in 50–90% of the plants at variable titers, indicating that the 52 °C hot water treatment for 30 min was not effective in eradicating Lxx from all plants. However, in the second experiment the bacterial population was reduced, as the median number of Lxx cells was lower compared to the non-treated control. In the case of SP70-3370, the treatment also reduced the number of Lxx-infected plants considering the pooled data of the two experiments. The results indicated that although the 52 °C hot water treatment for 30 min did not completely eliminate Lxx, it can be used to reduce the pathogen population in plants propagated from canes with high Lxx titer

Controle da mancha foliar de Eucalyptus grandis e E. urophylla induzida por Cylindrocladium scoparium com Bacillus sp.

Foram obtidos isolados de Bacillus sp. oriundos de Eucalyptus grandis, antagonicos a Cylindrocladium scoparium. Após a seleção do isolado mais eficiente em inibir C. scoparium, in vitro, este foi multiplicado em BD (batata-dextrose) e incorporado em meio de BDA, verificando-se uma relação direta entre a concentração do meio BD, incorporado, e a inibicao do crescimento micelial do patógeno. Uma cultura liquida (BD) de Bacillus sp. (AP-28) com 10 dias de idade aplicada uniformemente sobre folhas destacadas de E. grandis e E. urophylla 1, 24 e 48 horas antes da inoculação de uma suspensão com conidios de C. scoparium (10 4 esporos/ml), apresentou controle semelhante ao benomyl (0,5 g/l). Por outro lado, Bacillus sp. nao apresentou controle do patógeno, quando aplicado 24 e 48 horas após a inoculacao de C. scoparium. Não foram verificados efeitos fitopatológicos do Bacillus sp. e nem efeitos fitotóxicos de seus metabólitos.Made available in DSpace on 2017-01-16T23:00:29Z (GMT). No. of bitstreams: 1 1998AP008BettiolControle1397.PDF: 527010 bytes, checksum: 5b36846a3c9e6a9b7677c9b8c4c96650 (MD5) Previous issue date: 1993-08-04198

Controle da mancha foliar de Eucalyptus grandis e E. urophylla induzida por Cylindrocladium scoparium com Bacillus sp.

Foram obtidos isolados de Bacillus sp. oriundos de Eucalyptus grandis, antagonicos a Cylindrocladium scoparium. Após a seleção do isolado mais eficiente em inibir C. scoparium, in vitro, este foi multiplicado em BD (batata-dextrose) e incorporado em meio de BDA, verificando-se uma relação direta entre a concentração do meio BD, incorporado, e a inibicao do crescimento micelial do patógeno. Uma cultura liquida (BD) de Bacillus sp. (AP-28) com 10 dias de idade aplicada uniformemente sobre folhas destacadas de E. grandis e E. urophylla 1, 24 e 48 horas antes da inoculação de uma suspensão com conidios de C. scoparium (10 4 esporos/ml), apresentou controle semelhante ao benomyl (0,5 g/l). Por outro lado, Bacillus sp. nao apresentou controle do patógeno, quando aplicado 24 e 48 horas após a inoculacao de C. scoparium. Não foram verificados efeitos fitopatológicos do Bacillus sp. e nem efeitos fitotóxicos de seus metabólitos

Development of a qPCR for Leifsonia xyli subsp. xyli and quantification of the effects of heat treatment of sugarcane cuttings on Lxx

The main control practice of Leifsonia xyli subsp. xyli (Lxx) in sugarcane is to heat-treat cane cuttings used as planting material in an attempt to eradicate the bacterium. A real time quantitative PCR (qPCR) protocol specific for Lxx was developed to assess the effectiveness of this practice. Primers were designed from the sequence of an Lxx-specific gene and detected as few as 10−5 ng of Lxx DNA in 100 ng of plant DNA. Two experiments were conducted to quantify Lxx titers in plants of the varieties SP80-3280 and SP70-3370 originated from cuttings treated or not by immersion in hot water at 52 °C for 30 min. In the first experiment, cuttings were collected from plant canes with low Lxx titers whereas in the second they were collected from first-ratoon canes with higher titers. Lxx was quantified in leaves by qPCR 90 days after planting and was detected in 50–90% of the plants at variable titers, indicating that the 52 °C hot water treatment for 30 min was not effective in eradicating Lxx from all plants. However, in the second experiment the bacterial population was reduced, as the median number of Lxx cells was lower compared to the non-treated control. In the case of SP70-3370, the treatment also reduced the number of Lxx-infected plants considering the pooled data of the two experiments. The results indicated that although the 52 °C hot water treatment for 30 min did not completely eliminate Lxx, it can be used to reduce the pathogen population in plants propagated from canes with high Lxx titer

Increasing The Density Of Markers Around A Major Qtl Controlling Resistance To Angular Leaf Spot In Common Bean

Angular leaf spot (ALS) causes major yield losses in the common bean (Phaseolus vulgaris L.), an important protein source in the human diet. This study describes the saturation around a major quantitative trait locus (QTL) region, ALS10.1, controlling resistance to ALS located on linkage group Pv10 and explores the genomic context of this region using available data from the P. vulgaris genome sequence. DArT-derived markers (STS-DArT) selected by bulk segregant analysis and SCAR and SSR markers were used to increase the resolution of the QTL, reducing the confidence interval of ALS10.1 from 13.4 to 3.0 cM. The position of the SSR ATA220 coincided with the maximum LOD score of the QTL. Moreover, a new QTL (ALS10.2UC) was identified at the end of the same linkage group. Sequence analysis using the P. vulgaris genome located ten SSRs and seven STS-DArT on chromosome 10 (Pv10). Coincident linkage and genome positions of five markers enabled the definition of a core region for ALS10.1 spanning 5.3 Mb. These markers are linked to putative genes related to disease resistance such as glycosyl transferase, ankyrin repeat-containing, phospholipase, and squamosa-promoter binding protein. Synteny analysis between ALS10.1 markers and the genome of soybean suggested a dynamic evolution of this locus in the common bean. The present study resulted in the identification of new candidate genes and markers closely linked to a major ALS disease resistance QTL, which can be used in marker-assisted selection, fine mapping and positional QTL cloning. © 2013 Springer-Verlag Berlin Heidelberg.11