Malleola tibetica sp. nov. (Aeridinae,Orchidaceae) from Tibet,China

Malleola tibetica, a new species from southeastern tropical Tibet, China, is described and illustrated. Morphologically, the new species is closely related to M. dentifera, but differs from it by having uniformly green leaves, flowers with entire lateral lobes of the lip and a basally thickened mid‐lobe, and a column that is densely cristaline‐papillose adaxially.     

Influence of sucrose concentration and phosphate source on biomass and metabolite accumulation in adventitious roots of Pseudostellaria heterophylla

In this study, we investigated the induction of Pseudostellaria heterophylla adventitious root and the effects of sucrose concentration and phosphate source on biomass increase and metabolites accumulation. These roots were initially cultured in Murashige and Skoog medium for 4 weeks. IBA 3.0 mg L^?1 proved to be the best auxin for inducing adventitious roots and the frequency of adventitious roots induced from roots (100 %) was higher than that from leaves (78 %) and stems (27 %). The medium with 4 % sucrose resulted in the optimum biomass i.e. 1.04 g/flask DW, and the content of saponin and polysaccharides reached the peak i.e. 0.676 and 24.4 %, respectively. With regards to phosphate source, 1.25 mM phosphate concentration was more favorable for biomass of roots (0.87 g/flask of DW), whereas the optimum saponin (0.74 %) and polysaccharides (22.09 %) were achieved with 2.5 mM phosphate. However, the saponin content at 2.5 mM phosphate did not show significant difference from the saponin content at 0.625 mM (0.69 %) or 3.75 mM phosphate (0.69 %).     

Characterization of five CIPK genes expressions in maize under water stress

ABA, H₂O₂ and Ca²⁺ play critical roles as signals in the adaptive responses of plants to water and other stresses. They accumulate in plant cells under water and other stresses and induce changes in stress-related gene expressions. CIPKs, protein kinases associated with a calcineurin B-like calcium sensor, play a role in the regulation of stress gene expression in plants. However, it is still unclear whether ABA and H₂O₂ are key inducers that regulate the changes in CIPK expressions under water stress. In this study, five stress-inducible CIPKs in maize were retrieved from Database. They were designated as ZmCIPK1, 3, 8, 17 and 18, based on their homologies with known CIPK sequences. The expressions of the five ZmCIPKs in maize leaves and roots were analyzed and found to be regulated by PEG, CaCl₂, ABA and H₂O₂ to different extents. Moreover, the effect of ABA and H₂O₂ on the expressions of ZmCIPKs under water stress was in an organ-dependent manner.     

Myosin-cross-reactive antigens from four different lactic acid bacteria are fatty acid hydratases

The 67 kDa myosin-cross-reactive antigen (MCRA) is a member of the MCRA family of proteins present in a wide range of bacteria and was predicted to have fatty acid isomerase function. We have now characterised the catalytic activity of MCRAs from four LAB stains, including Lactobacillus rhamnosus LGG, L. plantarum ST-III, L. acidophilus NCFM and Bifidobacterium animalis subsp. lactis BB-12. MCRA genes from these strains were cloned and expressed in Escherichia coli, and the recombinant protein function was analysed with lipid profiles by GC–MS. The four MCRAs catalysed the conversion of linoleic acid and oleic acid to their respective 10-hydroxy derivatives, which suggests that MCRA proteins catalyse the first step in conjugated linoleic acid production. This is the first report of MCRA from L. rhamnosus with such catalytic function.     

Rubia austrozhejiangensis sp. nov. (Rubiaceae) from Zhejiang,China

Rubia austrozhejiangensis Z. P. Lei, Y. Y. Zhou & R. W. Wang, a new species of Rubiaceae from China, is described and illustrated. The new species is similar to R. ovatifolia Z. Ying Zhang and R. argyi (H. Lév. & Vaniot) H. Hara ex Lauener, but differs from the former in having stems and branches cylindrical, not quadrate‐angled, long‐ovate to ovate‐lanceolate leaf blades, many‐flowered inflorescence, and smaller mericarps, 3–4 mm in diameter. In R. ovatifolia, stems and branches are quadrate‐angled, leaf blades ovate, ovate‐cordate to rounded cordate, and the inflorescences are sparsely flowered. Compared to R. argyi, the new species has cylindrical, not quadrate‐angled stems and branches, leaf blades that are long‐ovate to ovate‐lanceolate, 3–5‐veined, and slightly reflexed corolla lobes. In R. argyi, stems and branches are quadrate‐angled or winged, the corolla lobes are spreading, and the mericarps are 5–7 mm in diameter.     

CmPEX6, a Gene Involved in Peroxisome Biogenesis,Is Essential for Parasitism and Conidiation by the Sclerotial Parasite Coniothyrium minitans

Coniothyrium minitans is a sclerotial parasite of the plant-pathogenic fungus Sclerotinia sclerotiorum, and conidial production and parasitism are two important aspects for commercialization of this biological control agent. To understand the mechanism of conidiation and parasitism at the molecular level, we constructed a transfer DNA (tDNA) insertional library with the wild-type strain ZS-1. A conidiation-deficient mutant, ZS-1TN22803, was uncovered through screening of this library. This mutant could produce pycnidia on potato dextrose agar (PDA), but most were immature and did not bear conidia. Moreover, this mutant lost the ability to parasitize or rot the sclerotia of S. sclerotiorum. Analysis of the tDNA flanking sequences revealed that a peroxisome biogenesis factor 6 (PEX6) homolog of Saccharomyces cerevisiae, named CmPEX6, was disrupted by the tDNA insertion in this mutant. Targeted gene replacement and gene complementation tests confirmed that a null mutation of CmPEX6 was responsible for the phenotype of ZS-1TN22803. Further analysis showed that both ZS-1TN22803 and the targeted replacement mutants could not grow on PDA medium containing oleic acid, and they produced much less nitric oxide (NO) and hydrogen peroxide (H₂O₂) than wild-type strain ZS-1. The conidiation of ZS-1TN22803 was partially restored by adding acetyl-CoA or glyoxylic acid to the growth media. Our results suggest that fatty acid β-oxidation, reactive oxygen and nitrogen species, and possibly other unknown pathways in peroxisomes are involved in conidiation and parasitism by C. minitans.