Extracts and purified substances of Cabralea canjerana inhibit hatching and extracts of Schinus terebinthifolius kill juveniles of meloidogyne incognita

Nematicidal substances have been identified from plants and are potentially useful for the management of plant-parasitic nematodes. Cabralea canjerana, (Meliaceae) and Schinus terebinthifolius (Anacardiaceae) produce bioactive compounds during their secondary metabolism and little is known about the effect of such substances on plant-parasitic nematodes. In the present study, we assessed the effect of aqueous and ethanolic extracts of C. canjerana and S. terebinthifolius at 1% (m:v) and purified substances from C. canjerana (gedunin, ocotillone, cabraleadiol, a mixture of ocotillone + cabraleadiol and a mixture of shoreic acid + eichlerianic acid) on hatching and mortality of Meloidogyne incognita juveniles. Aqueous extracts of C. canjerana fruits and seeds reduced hatching by 70.3 to 95.7%. Aqueous extracts of S. terebinthifolius fruits killed 42.8 to 77.1% of juveniles. The purified substances of C. canjerana inhibited the hatching of M. incognita from 57 to 90% and did not increase the mortality of juveniles. Therefore, C. canjerana extracts and its purified substances reduce M. incognita hatching and aqueous extracts of S. terebinthifolius kill J2 of this nematode.

Complete Genome Sequence of the Biocontrol Agent Bacillus velezensis UFLA258 and Its Comparison with Related Species: Diversity within the Commons.

In this study, the full genome sequence of Bacillus velezensis strain UFLA258, a biological control agent of plant pathogens was obtained, assembled, and annotated. With a comparative genomics approach, in silico analyses of all complete genomes of B. velezensis and closely related species available in the database were performed. The genome of B. velezensis UFLA258 consisted of a single circular chromosome of 3.95 Mb in length, with a mean GC content of 46.69%. It contained 3,949 genes encoding proteins and 27 RNA genes. Analyses based on Average Nucleotide Identity and Digital DNA-DNA Hybridization and a phylogeny with complete sequences of the rpoB gene confirmed that 19 strains deposited in the database as Bacillus amyloliquefaciens were in fact B. velezensis. In total, 115 genomes were analyzed and taxonomically classified as follows: 105 were B. velezensis, 9 were B. amyloliquefaciens, and 1 was Bacillus siamensis. Although these species are phylogenetically close, the combined analyses of several genomic characteristics, such as the presence of biosynthetic genes encoding secondary metabolites, CRISPr/Cas arrays, Average Nucleotide Identity and Digital DNA-DNA Hybridization, and other information on the strains, including isolation source, allowed their unequivocal classification. This genomic analysis expands our knowledge about the closely related species, B. velezensis, B. amyloliquefaciens, and B. siamensis, with emphasis on their taxonomical status.