Molecular phylogenetic analysis of bovine papular stomatitis viruses detected in Saga,Japan

In this study, we performed a molecular phylogenetic analysis of six bovine papular stomatitis virus (BPSV) field strains detected from Japanese beef calves kept on a farm in Saga prefecture, a southwest part of Japan, from 2017 to 2020. The phylogenetic analysis based on a partial B2L gene (554-nt) showed that these field strains were divided into two lineages, a lineage (A-lineage) constructed by a Saga strain and strains obtained from various regions of Japan and the world, and other lineage (B-lineage) constructed by five Saga strains and strains obtained from France, USA and Iwate prefecture (a north part of Japan). Furthermore, a Saga field strain named BPSV_SAGAbv2 and strains obtained from USA and Iwate prefecture belonged to a sub-lineage blanched from B-lineage. This is the first report elucidating molecular epidemiological characters of field BPSVs obtained from Saga prefecture. The existence of the multiple lineages was thought to be related to a history of calf introduction from various regions of Japan into Saga prefecture.     

Plant seed cystatins and their target enzymes of endogenous and exogenous origin

Cystatins are protein inhibitors of cysteine proteinases of the papain family, and those of animal origin have long been studied from medical and physiological aspects. In the meantime, oryzacystatin cloned from rice seeds in 1987 was recognized as the first well-defined cystatin of plant origin. Cloning studies followed to disclose various plant cytstatins including those of corn and soybean origin, their similarities to and differences from animal cystatins being analyzed in detail. Plant seed cystatins are now understood as factors controlling germination by inhibition of endogenous cysteine proteinases. They can also recognize insect midgut proteinases as exogenous target enzymes to control. This paper discusses chemical and phytophysiological relationships between cystatins and their targets.     

Induction of reactive oxygen generation and functional changes in mitochondria and their involvement in the development of bacterial rot in lettuce caused by Pseudomonas cichorii

Pseudomonas cichorii is the major causal agent of bacterial rot disease in lettuce, and apoptosis-like programmed cell death is closely associated with disease development. Depletion of cellular ATP and expression of the alternative oxidase gene was observed in lettuce leaves inoculated with P. cichorii suggesting mitochondrial dysfunction. Cytochemical observation showed production of reactive oxygen species in mitochondria of P. cichorii-inoculated lettuce leaf cells. Release of cytochrome c into the cytosol was also induced by inoculation with the bacterium. Superoxide production was observed in the mitochondrial fraction isolated from P. cichorii-infected leaves much more intense than water-treated leaves. Loss of swelling ability was also observed in the mitochondrial fractions following inoculation with P. cichorii. Intriguingly, inhibitors of the mitochondrial respiratory complex III prevented loss of swelling ability, whereas superoxide generation was scarcely affected by inhibitors of mitochondrial permeability transition in the mitochondrial fractions. Inhibitors of the mitochondrial respiratory complex III and mitochondrial permeability transition delayed not only P. cichorii-induced cell death, but also disease development. In contrast, P. cichorii-induced DNA fragmentation was not inhibited in the presence of either type of inhibitor. The findings suggest that mitochondria may play a crucial role in DNA fragmentation-independent cell death pathway(s).     

QTL analysis of leaf photosynthetic rate and related physiological traits in rice (Oryza sativa L. )

Photosynthesis is one of the most important factors that influence the biomass and yield.     

Internal fruit rot of netted melon caused by <Emphasis Type="Italic">Pantoea ananatis</Emphasis> (=<Emphasis Type="Italic">Erwinia ananas</Emphasis>) in Japan

An internal fruit rot with a malodor was found in netted melons (Cucumis melo L.) in commercial greenhouses in Kochi Prefecture, Japan, in 1998, despite their healthy appearance and lack of water-soaking or brown spots on the surface. A yellow bacterium was consistently isolated from the affected fruits. To confirm the pathogenicity of eight representative isolates of the yellow bacterium, we stub-inoculated ovaries (immature-fruits) 5–7 days after artificial pollination, with a pin smeared with bacteria. After the melon fruits had grown for 60 more days, an internal fruit rot resembling the natural infection appeared, and the inoculated bacterium was reisolated. The melon isolates had properties identical with Pantoea ananatis, such as gram-negative staining, facultative anaerobic growth, indole production, phenylalanine deaminase absence, and acid production from melibiose, sorbitol, glycerol, and inositol. Phylogenetic analysis based on 16S rDNA sequences showed that the melon bacterium positioned closely with known P. ananatis strains. The melon bacterium had indole acetic acid (IAA) biosynthesis genes (iaaM and iaaH) and a cytokinin biosynthesis gene (etz). The bacterium could be distinguished from the other ‘Pantoea’ group strains by rep-PCR genomic fingerprinting. From these results, the causal agent of internal fruit rot was identified as a strain of P.ananatis [Serrano in (Philipp J Sci 36:271–305, 1928); Mergaert et al. in (Int J Syst Bacteriol 43:162–173, 1993)]. The nucleotide sequence data reported are available in the DDBJ database under accessions AB297969, AB373739, AB373740, AB373741, AB373742, AB373743 and AB373744.     

Involvement of HLK effectors in Ralstonia solanacearum disease development in tomato

A multigene family encoding HLK effectors is well conserved in all Ralstonia solanacearum strains. The HLK family contains three paralogous members. We constructed single, double, and triple deletion mutants of hlk genes in R. solanacearum strain OE1-1 and characterized HLK effectors by comparing the phenotypes of the strains. HLK effectors exhibited some functional redundancy. While the triple deletion mutant was significantly impaired in virulence on tomato and multiplied less efficiently than the wild type in the leaves, the mutant was as virulent as the wild type on eggplant and tobacco.