Nocardia mangyaensis sp. nov., a novel actinomycete isolated from crude-oil-contaminated soil.

A Gram-stain-positive, aerobic, non-motile and mycolic-acid-containing strain, designated Y48T, was isolated from soil contaminated by crude oil located in the northern margin of the Qaidam Basin. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Y48T belongs to the genus Nocardia and is closely related to N. cummidelens DSM 44490T (99.0 % similarity), N. soli DSM 44488T (99.0 %), N. lasii 3C-HV12T (98.9 %), N. salmonicida NBRC 13393T (98.6 %), N. ignorata NBRC 108230T (98.6 %) and N. coubleae NBRC 108252T (98.6 %). The average nucleotide identity and DNA-DNA hybridization values between strain Y48T and the reference strains were 75.9-84.5 and 27.5-29.0 %, respectively, values that were below the thresholds for species delineation. Chemotaxonomic analysis indicated that the major fatty acids of strain Y48T were C16 : 0, summed feature 3 (C16 : 1ω6c/C16 : 1ω7c), C18 : 1ω9c and C18 : 0 10-methyl (TBSA). The respiratory quinone was MK-8(H4, ω-cycl). The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, two glycolipids and three unidentified lipids. The cell-wall hydrolysates contained meso-diaminopimelic acid, with ribose, arabinose, glucose and galactose as whole-cell sugars. A combination of 16S rRNA gene sequence analysis, and phenotypic and chemotaxonomic characterizations demonstrated that strain Y48T represents a novel species of the genus Nocardia, for which the name Nocardia mangyaensis sp. nov. is proposed. The type strain is Y48T (=JCM 32795T=CGMCC 4.7494T).

The magnesium-chelatase H subunit binds abscisic acid and functions in abscisic acid signaling: new evidence in Arabidopsis.

Using a newly developed abscisic acid (ABA)-affinity chromatography technique, we showed that the magnesium-chelatase H subunit ABAR/CHLH (for putative abscisic acid receptor/chelatase H subunit) specifically binds ABA through the C-terminal half but not the N-terminal half. A set of potential agonists/antagonists to ABA, including 2-trans,4-trans-ABA, gibberellin, cytokinin-like regulator 6-benzylaminopurine, auxin indole-3-acetic acid, auxin-like substance naphthalene acetic acid, and jasmonic acid methyl ester, did not bind ABAR/CHLH. A C-terminal C370 truncated ABAR with 369 amino acid residues (631-999) was shown to bind ABA, which may be a core of the ABA-binding domain in the C-terminal half. Consistently, expression of the ABAR/CHLH C-terminal half truncated proteins fused with green fluorescent protein (GFP) in wild-type plants conferred ABA hypersensitivity in all major ABA responses, including seed germination, postgermination growth, and stomatal movement, and the expression of the same truncated proteins fused with GFP in an ABA-insensitive cch mutant of the ABAR/CHLH gene restored the ABA sensitivity of the mutant in all of the ABA responses. However, the effect of expression of the ABAR N-terminal half fused with GFP in the wild-type plants was limited to seedling growth, and the restoring effect of the ABA sensitivity of the cch mutant was limited to seed germination. In addition, we identified two new mutant alleles of ABAR/CHLH from the mutant pool in the Arabidopsis Biological Resource Center via Arabidopsis (Arabidopsis thaliana) Targeting-Induced Local Lesions in Genomes. The abar-2 mutant has a point mutation resulting in the N-terminal Leu-348-->Phe, and the abar-3 mutant has a point mutation resulting in the N-terminal Ser-183-->Phe. The two mutants show altered ABA-related phenotypes in seed germination and postgermination growth but not in stomatal movement. These findings support the idea that ABAR/CHLH is an ABA receptor and reveal that the C-terminal half of ABAR/CHLH plays a central role in ABA signaling, which is consistent with its ABA-binding ability, but the N-terminal half is also functionally required, likely through a regulatory action on the C-terminal half.