Vibrio coralliilyticus is a bacterial pathogen which can affect a range of marine organisms, such as corals, fish and shellfish, with sometimes devastating consequences. However, little is known about the mechanisms involved in the host-pathogen interaction, especially within molluscan models. We applied gas chromatography-mass spectrometry (GC-MS)-based metabolomics to characterize the physiological responses in haemolymph of New Zealand Greenshell™ mussels (Perna canaliculus) injected with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Univariate data analyses of metabolite profiles in Vibrio-exposed mussels revealed significant changes in 22 metabolites at 6 h post-infection, compared to non-exposed mussels. Among them, 10 metabolites were up-regulated, while 12 metabolites were down-regulated in infected mussels. Multivariate analyses showed a clear distinction between infected and non-infected mussels. In addition, secondary pathway analyses indicated perturbations of the host innate immune system following infection, including oxidative stress, inflammation and disruption of the TCA cycle, change in amino acid metabolism and protein synthesis. These findings provide new insights into the pathogenic mechanisms of Vibrio infection of mussels and demonstrate our ability to detect detailed and rapid host responses from haemolymph samples using a metabolomics approach.

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Article Information A rot disease was observed on onion bulbs in major growing areas of Kadapa and Kurnool districts of Andhra Pradesh, India during 2010 to 2012. Based on pathogenicity, morphology and ribosomal DNA spacer sequences, the pathogen was identified as Fusarium proliferatum (Matsushima) Nirenberg. The fungus was isolated from onion bulbs presenting purple and reddish lesions, obtaining F. proliferatum consistently. The fungus produced effuse white colonies, branched hyphae, short conidiophores, slightly curved macroconidia, and single celled microconidia measuring 5.6-10.5 X 2.0-3.5 μm in diameter. Morphological identification of the fungus was confirmed using ribosomal DNA sequence data. Kotch's postulates were confirmed by performing pathogenicity test on healthy onion bulbs. This is the first report of F. proliferatum causing rot disease on onion bulbs in India; although it had already been reported for onion in the USA and Serbia.

Aims Despite a large number of studies examining the effects of abiotic stress factors on plants, the mechanistic explanations of drought-induced tree mortality remain inconclusive and even less is known about how multiple stressors interact. The role of non-structural carbohydrates (NSCs) in preventing or postponing drought mortality is gaining attention. Here we tested the role of NSCs in mitigating the effects of drought and salinity in New Zealand mangroves, Avicennia marina subsp. australasica. Methods We experimentally manipulated plant NSC levels, prior to subjecting them to combinations of drought and salinity. Important Findings Plant growth and survival rates were two and three-fold higher in the high-NSC group (H-NSC) than in the low-NSC (L-NSC) group under high salinity and drought conditions, respectively. After 12 weeks under high salinity – high drought conditions, the H-NSC group showed higher stem hydraulic conductivity (281 ± 50 mmol cm -1 s -1 MPa -1) compared to the L-NSC group (134 ± 40 mmol cm -1 s -1 MPa -1). Although starch levels remained relatively constant, we found a 20 % increase in soluble sugars in the stems of H-NSC group under high drought and high salinity in week 8 compared to week 12. Our results suggest 1) an important role of NSCs in mitigating the effects of low soil water potential caused by drought and salinity, and 2) sink-limited growth under conditions of combined salinity and drought.