Identification of Mulberry Bacterial Blight Caused by Klebsiella oxytoca in Bazhong,Sichuan,China

To provide a scientific basis for controlling mulberry bacterial blight in Bazhong,Sichuan,China(BSC),this study aimed to isolate and purify pathogenic bacteria from diseased branches of mulberry trees in the region and to clarify their taxonomic status using morphological observation,physiological and biochemical detection,molecular-level identification,and the construction of a phylogenetic tree.A total of 218 bacterial strains were isolated from samples of diseased mulberry branches.Of these,7 strains were identified as pathogenic bacteria based on pathogenicity tests conducted in accordance with Koch’s postulates.Preliminary findings from the analysis of the 16S rRNA sequence indicated that the 7 pathogenic bacteria are members of Klebsiella spp.Morphological observation revealed that the pathogenic bacteria were oval-shaped and had capsules but no spores.They could secrete pectinase,cellulase,and protease and were able to utilize D-glucose,D-mannose,D-maltose,and D-Cellobiose.The 7 strains of pathogenic bacteria exhibited the highest homology with Klebsiella oxytoca.This study identifies Klebsiella oxytoca as the causative agent of mulberry bacterial blight in BSC,laying the foundation for the prevention and control of this pathogen and further investigation into its pathogenic mechanism.

Efficient generation of targeted point mutations in the Brassica oleracea var.botrytis genome via a modified CRISPR/Cas9 system

In this study,we used the modified CRISPR/Cas9 system to produce targeted point mutations in cauliflower.Acetolactate synthase(ALS)and Centromere-specific histone H3 variant(CENH3)genes were selected as the base-editing targets and hypocotyls of cauliflower were used as explants.For ALS gene,a C-to-T conversion in the Pro182 codon(CCT)can alter the encoded amino acid,likely resulting in herbicide resistance,and a C-to-T mutation in the Leu133 codon(CTT)in the CENH3 gene may produce a haploid inducer.Results indicated that the transformation efficiency was 1.8%–4.5%and the mutation efficiencies for the ALS and CENH3 genes were approximately 22%and 87%,respectively.The ALS mutant cauliflower showed strong herbicide resistance,with possible immediate implications for broadleaf weed control in cauliflower fields.

A graph-based pan-genome of Brassica oleracea provides new insights into its domestication and morphotype diversification

The domestication of Brassica oleracea has resulted in diverse morphological types with distinct patterns of organ development.Here we report a graph-based pan-genome of B.oleracea constructed from high-quality genome assemblies of different morphotypes.The pan-genome harbors over 200 structural variant hotspot regions enriched in auxin-andflowering-related genes.Population genomic analyses revealed that early domestication of B.oleracea focused on leaf or stem development.Geneflows resulting from agricultural practices and variety improvement were detected among different morphotypes.Selective-sweep and pan-genome analyses identified an auxin-responsive small auxin up-regulated RNA gene and a CLAV-ATA3/ESR-RELATED family gene as crucial players in leaf–stem differentiation during the early stage of B.oleracea domestication and the BoKAN1 gene as instrumental in shaping the leafy heads of cabbage and Brussels sprouts.Our pan-genome and functional analyses further revealed that variations in the BoFLC2 gene play key roles in the divergence of vernalization andflowering characteristics among different morphotypes,and variations in thefirst intron of BoFLC3 are involved infine-tuning theflowering process in cauliflower.This study provides a comprehensive understanding of the pan-genome of B.oleracea and sheds light on the domestication and differential organ development of this globally important crop species.

In vivo haploid induction in cauliflower,kale,and broccoli

Brassica oleracea (family Brassicaceae) represents a group of economically valuable vegetables cultivated worldwide,including cabbage (var. capitata), cauliflower (var. botrytis),broccoli (var. italica), and kale (var. acephala). These crops are typically self-incompatible and require vernalization for flowering, thereby contributing to their long growth cycles.