Draft Genome Sequences of Three Strains of Pseudomonas syringae pv. eriobotryae, a Pathogen Causing Canker Disease in Loquat, Isolated in Japan

The phytopathogenic bacterium Pseudomonas syringae pv. eriobotryae causes canker disease in loquat. Isolates from Japan are classified into three groups based on pathogenicity and pigment production. In this study, we report the draft genome sequences of three strains, one belonging to each of the three groups.

L oquat (Eriobotrya japonica [Thunb.] Lindl.), a subtropical evergreen fruit tree, is widely cultivated in subtropical regions. Pseudomonas syringae pv. eriobotryae causes loquat canker disease, the most serious disease in loquat cultivation (1). Isolates from Japan are classified into three groups: group A is not pathogenic to mesophyll and produces no pigment in culture medium; group B is pathogenic to mesophyll and produces no pigment; group C is not pathogenic to mesophyll and produces brown pigment (2). In loquat, a single dominant gene (Pse-a) controls resistance to group A (3), and a single recessive gene (Pse-c) controls resistance to group C (4). Here, we report the draft genome sequences of three strains isolated in Japan (AM001, BM001, and CG001), one from each group.
The resulting genome assemblies are shown in Table 1.
The draft genome sequences of five Pseudomonas strains pathogenic to loquat (CFBP2343, ICMP4316, ICMP4455, ICMP4967, and ICMP8636) are available in DDBJ/ EMBL/GenBank. The source of ICMP8636 is unknown; the other four strains were isolated in the United States. We additionally used the genome sequences of 10 Pseudomonas strains pathogenic to the other plants (1448A, KBS0707, ATCC 11528, FTRS U6602, FTRS U6603, NCPPB3335, R15244, CFBP3840, CFBP2116, and LMG5095) to construct a phylogenetic tree (Fig. 1). In this tree, two Japanese strains (AM001 and CG001), three U.S. strains (CFBP2343, ICMP4316, and ICMP4455), and ICMP8636 formed a single clade. Because loquat was introduced into the United States from Japan or China, the three U.S. strains and ICMP8636 probably came from East Asia. Interestingly, one of the Japanese strains, BM001, was closely related to P. savastanoi pv. savastanoi NCPPB3335, the causal agent of olive knot disease. Mechanisms such as horizontal gene transfer and hybridization might have genetically separated BM001 from the other two Japanese strains. More interestingly, one of the U.S. strains, ICMP4967, was genetically distant from the other seven strains. Although further study is required, the progenitor of this strain might have been present in the United States before the introduction of loquat. The draft genome sequences reported here will provide fundamental information for elucidating the mechanisms of infection of P. syringae pv. eriobotryae and facilitate progress toward protection against this pathogen.
Data availability. The draft genome sequences and corresponding read data are available in DDBJ/GenBank. The DDBJ/GenBank and SRA accession numbers for P. syringae pv. eriobotryae AM001, BM001, and CG001 are listed in Table 1.

ACKNOWLEDGMENT
This work was partially supported by JSPS KAKENHI grant number 18K05624.