Abstract Banana vascular wilt or Moko is a disease caused by Ralstonia solanacearum. This study aimed to sequence, assemble, annotate, and compare the genomes of R. solanacearum Moko ecotypes of different sequevar strains from Brazil. Average nucleotide identity analyses demonstrated a high correlation (> 96%) between the genome sequences of strains CCRMRs277 (sequevar IIA-24), CCRMRs287 (IIB-4), CCRMRs304 (IIA-24), and CCRMRsB7 (IIB-25), which were grouped into phylotypes IIA and IIB. The number of coding sequences present in chromosomes and megaplasmids varied from 3,070 to 3,521 and 1,669 to 1,750, respectively. Pangenome analysis identified 3,378 clusters in the chromosomes, of which 2,604 were shared by all four analyzed genomes and 2,580 were single copies. In megaplasmids, 1,834 clusters were identified, of which 1,005 were shared by all four genomes and 992 were identified as single copies. Strains CCRMRsB7 and CCRMRs287 differed from the others by having unique clusters in both their chromosomes and megaplasmids, and CCRMRsB7 possessed the largest genome among all Moko ecotype strains sequenced to date. Therefore, the genomic information obtained in this study provides a theoretical basis for the identification, characterization, and phylogenetic analysis of R. solanacearum Moko ecotypes.

Abstract Ralstonia solanacearum is the causal agent of Moko disease in bananas, which in the state of Sergipe in northeastern Brazil causes “Sergipe facies”. This disease induces atypical symptoms similar to those of Bugtok disease in the Philippines. This study was conducted to sequence, assemble, and annotate the genomes of the Sergipe facies-causing isolates SFC and IBSBF2570 (sequevar IIA-53) and compare their genomes with two representative isolates causing Bugtok disease. The genomes were sequenced and assembled, resulting in lengths of 5.58 Mb (SFC) and 5.46 Mb (IBSBF2570) in 185 and 174 contigs, respectively. The isolates of Sergipe facies and Bugtok disease showed similarities in their gene contents. We identified 5,668 information clusters, 3,752 of which were shared by all genomes (core genes). Moreover, 3,585 single-copy genes were identified. Isolates causing Bugtok disease exclusively shared 266 more information clusters than the isolates causing Sergipe facies. These results suggest that Sergipe facies and Bugtok disease isolates show high genomic similarity. However, the similarity is even greater between the Bugtok disease isolates. This may be because of their longer period of interaction compared to Sergipe facies isolates.

ABSTRACT Bacterial fruit blotch (BFB) of cucurbit plants is caused by Acidovorax citrulli and represents a serious concern to melon (Cucumis melo L.) growers worldwide, including those in Brazil. Thirty-four A. citrulli strains from different melon production areas of northeastern Brazil were characterized for their virulence on melon fruits and their substrate utilization and molecular profiles. Based on the analysis of BFB severity on melon fruits, the A. citrulli strains were divided into three groups, classified as mildly, moderately or highly virulent. Although host-related groups were not observed, the watermelon and ‘melão-pepino’ strains exhibited only low or moderate virulence on melon fruit. Substrate utilization profiles revealed that 94 % of the 95 tested compounds were used by A. citrulli strains as a carbon source. Overall, based on substrate utilization, low variability was observed with no relationship to host of origin. The formation of one group of A. citrulli strains based on Repetitive Sequence-based PCR (rep-PCR) analysis confirmed the low variability observed in the substrate utilization analyses. Bayesian inference based on the analysis of 23S rDNA partial sequence data resulted in one well-supported clade and clustered the strains with the A. citrulli-type species with high posterior probability support. Based on the markers used, the Brazilian A. citrulli strains belong to a single group, which corresponds to the previously described Group I for this bacterium in the United States.

Foi estudado o efeito de acibenzolar-S-metil (ASM), mananoligossacarídeos (MOS) e bioflavonóides cítricos (BFC) no controle da mancha-aquosa causada por Acidovorax citrulli em meloeiros tipo Amarelo (híbrido AF4945) e tipo Pele de Sapo (híbrido Nilo), em diferentes épocas de aplicação (10 e 15 dias após a emergência das plântulas) e dosagens (ASM 25; 50 e 75 mg i.a. L-1; MOS 0,5; 1,0 e 1,5 p.c. L-1; BFC 2; 3 e 4 mL p.c. L-1); e também no crescimento da planta em solo com ou sem suplementação de NPK. A melhor época para aplicação dos indutores foi dez dias após a emergência das plântulas. Considerando os dois genótipos, ASM (50 mg i.a. L-1) e BFC (3 mL p.c. L-1) elevaram o período de incubação em até 13 e 8 dias e reduziram a incidência da mancha-aquosa em 88 e 60%; o índice de doença em 96 e 88%; e a área abaixo da curva de progresso da doença em 94 e 74%, respectivamente. No entanto, independente do nível de NPK no solo, ASM e BFC reduziram a altura, biomassa fresca e seca da parte aérea das plantas de meloeiro em até 24; 41 e 34%, respectivamente.

The effect of acibenzolar-S-methyl (ASM), mannano-oligosaccharides (MOS) and citrus bioflavonoids (BFC) was studied for control of bacterial fruit blotch of yellow melon (hybrid AF4945) and Pele de Sapo melon (hybrid Nilo), evaluating different application periods (10 and 15 days after plant emergence), and dosages (acibenzolar-S-methyl 25; 50 and 75 mg a.i. L-1; mannano-oligosaccharides 0.5; 1.0 and 1.5 c.p. L-1; citrus bioflavonoids 2; 3 and 4 mL c.p. L-1) and also on plant growth in soil supplemented or not with NPK. The best period for application was 10 days after plant emergence. Considering both genotypes, ASM (50 mg a.i. L-1) and BFC (3 mL c.p. L-1) increased incubation period until 13 and 8 days and reduced disease incidence by 88 and 60%; disease index by 96 and 88%; and area under disease progress curve by 94 and 74%, respectively. However, independent of NPK level in the soil ASM and BFC reduced melon plant height by 24%; they also reduced fresh and dry shoot biomass by 41% and 34%, respectively.