Hydrogen sulfide treatment improves quality attributes via regulating the antioxidant system in goji berry (Lycium barbarum L.).

Hydrogen sulfide (H2S) has been identified as a critical gaseous signaling chemical. Herein, the effects of H2S treatment on the postharvest goji berries and antioxidant enzyme activities were determined. H2S application delayed the decay index, loss of firmness, color, flavor, and total sugars and loss of total protein, betaine and ascorbic acid in goji berries during postharvest storage. Meanwhile, H2S noticeably reduced the MDA, H2O2, and O2- accumulation. Additionally, it was shown that H2S increased the activity of catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), glutathione reductase (GR) and superoxide dismutase (SOD) while decreased the quantity of lipoxygenase (LOX). The mRNA expression of LDC, DCD, CAT, APX, POD, GR and SOD was up-regulated but LOX, RBOH-b and RBOH-e was down-regulated in goji berries after H2S treatment. Altogether, H2S could efficiently delay the senescence, improves postharvest quality, increase the bioactive compounds accumulation, and boost the antioxidant capacity of goji berries through modulating antioxidant enzyme system.

Enhanced sensing of ascorbic acid, dopamine and serotonin at solid carbon paste electrode with a nonionic polymer film.

A nonionic poly(2-amino-5-mercapto-thiadiazole) film was electrodeposited on a solid carbon paste electrode via a potential scanning procedure, and used for amperometric sensing of ascorbic acid (AA), dopamine (DA) and serotonin (ST). The highly electrocatalytic activity of the sensor to the three analytes was demonstrated from the sensitive and well separated voltammetric signals. The polymer film did not show significant accumulation effect on all the three species, reducing the fouling and deactivation of the electrode surface as well as the mutual interference among the analytes. The sensor achieved amperometric sensitivities of 1.92 nA (nmol L(-1))(-1)cm(-2) to AA in the linear range of 0.025-1.95 µmol L(-1), 3.76 nA (nmol L(-1))(-1)cm(-2) to DA and 7.00 nA (nmol L(-1))(-1)cm(-2) to ST both in the linear range of 0.02-1.56 µmol L(-1). The lowest detection limits were found to be 1.5, 0.7 and 0.4 nmol L(-1) for AA, DA and ST, respectively. This sensor was successfully employed for the successive determination of AA, DA and ST in pharmaceutical samples. The good antifouling property and reproducibility of the proposed sensor can be attributed to the nonionic polymer film without electrostatic attraction to the ionized species in the solutions.

[Hydrogen peroxide is involved in regulation of tobacco leaf senescence].

Effects of various exogenous hydrogen peroxide (H2O2) concentrations on leaf senescence of tobacco (Nicotiana tabacum L.) were studied. The results showed that 0.1 and 1 mmol/L H2O2 had little effects on the leaf senescence of tobacco, the contents of chlorophyll and soluble protein were decreased in varying degrees by 10, 100 mmol/L H2O2 treatment, the decreased chlorophyll and soluble protein contents were significantly correlated with increased endogenous H2O2 content. SDS-PAGE of soluble protein and localized staining of H2O2 showed consistency with respective content. Chloroplast ultrastructure were observed in the mesophyll cells of tobacco and there was a little change by 10 mmol/L H2O2 treatment, and a remarkable breakdown of granal stacks and disorganized thylakoid membranes were revealed by 100, 200 mmol/L H2O2 treatment. RT-PCR analysis showed the expression level of senescence associated genes SAG12 was low by 10mmol/L H2O2 treatment and increased by 100 mmol/L H2O2 treatment. These results strongly suggested the tobacco leaf senescence was induced by 10 mmol/L H2O2 and accelerated the progression by high concentration (100, 200 mmol/L) H2O2 stress.

Species diversity of Lachnum (Helotiales, Hyaloscyphaceae) from temperate China.

Twenty-three temperate China species of Lachnum, Lachnum abnorme, L. angustum, L. brevipilosum, L. calosporum, L. calyculiforme, L. carneolum, L. ciliare, L. controversum, L. flavidulum, L. cf. fushanese, L. indicum, L. kumaonicum, L. lushanese, L. minutum, L. montanum, L. cf. pteridophyllum, L. pygmaeum, L. sclerotii var. sclerotii, L. sclerotii var. sichuanense, L. subpygmeaum, L. tenuissimum, L. virgineum and L. willisii are reported, whose main characteristics are given in a formula of the described species, some of which are discussed below.

Characterization of a novel developmentally retarded mutant (drm1) associated with the autonomous flowering pathway in Arabidopsis.

A developmentally retarded mutant (drm1) was identified from ethyl methanesulfonate (EMS)-mutagenized M2 seeds in Columbia (Col-0) genetic background. The drm1 flowers 109 d after sowing, with a whole life cycle of about 160 d. It also shows a pleiotropic phenotype, e.g., slow germination and lower germination rate, lower growth rate, curling leaves and abnormal floral organs. The drm1 mutation was a single recessive nuclear mutation, which was mapped to the bottom of chromosome 5 and located within a region of 20-30 kb around MXK3.1. There have been no mutants with similar phenotypes reported in the literature, suggesting that DRM1 is a novel flowering promoting locus. The findings that the drm1 flowered lately under all photoperiod conditions and its late flowering phenotype was significantly restored by vernalization treatment suggest that the drm1 is a typical late flowering mutant and most likely associated with the autonomous flowering pathway. The conclusion was further confirmed by the revelation that the transcript level of FLC was constantly upregulated in the drm1 at all the developmental phases examined, except for a very early stage. Moreover, the transcript levels of two other important repressors, EMF and TFL1, were also upregulated in the drm1, implying that the two repressors, along with FLC, seems to act in parallel pathways in the drm1 to regulate flowering as well as other aspects of floral development in a negatively additive way. This helps to explain why the drm1 exhibits a much more severe late-flowering phenotype than most late-flowering mutants reported. It also implies that the DRM1 might act upstream of these repressors.

[Screening for lifespan-extension mutants with paraquat in Arabidopsis].

Genetic analyses of lifespan in model animals have revealed that extended lifespans are closely associated to increased resistance to oxidative stress. In the model plant Arabidopsis, late-flowering mutants are also found to be more tolerant to oxidative stress. However, Arabidopsis mutants with extended lifespans are poorly studied so far. In this study, a screening system for mutants with extended lifespans in Arabidopsis was established using paraquat, a potent herbicide that exacerbates O2-. radical production. The relationship between lifespan and resistance to oxidative stress was examined with one of the mutants, SFNA-9-4. Compared to that of wild type, the lifespan of SFNA-9-4 is significantly extended, and its resistance to oxidative stress is also significantly elevated. These results suggest that, as in Drosophila, paraquat can also be used to screen for mutants with extended lifespans in Arabidopsis.