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Lycium barbarum Thunb. and Lycium ruthenicum Murray (wolfberries) have been utilized as traditional medicinal and nutritional plants in China for centuries. Much research has been focused on their high quality, yet the molecular mechanisms underlying morphological differences remain unclear. In this study, a comparative analysis of morphological and cytological characteristics indicated that significant differences existed. Meanwhile, transcriptomic analyses of the flower and fruit were performed at different developmental stages, and a total of 54 795 differentially expressed genes (DEGs) were screened. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed that these DEGs were significantly enriched in substance metabolism, catalytic activity, single organism process, starch and sucrose metabolism, carotenoid biosynthesis, amino sugar and nucleotide sugar metabolism, phenylpropanoid biosynthesis, and other pathways. Based on these significantly enriched pathways, the ratio between nonsynonymous and synonymous substitution rates (Ka/Ks), and numerous studies related to flower and fruit development, we preliminarily screened eight transcription factor families related to flower and fruit development and counted the number of potential transcription factor genes. These candidate genes could provide a basis for future functional verification, helping to further research on the molecular mechanism of morphological differences in the two Lycium species. [ABSTRACT FROM AUTHOR]

Seedling greening upon irradiance is essential for the survival of plant after germination. Here, we studied the role of nitric oxide (NO) in regulating the accumulation of chlorophyll during greening of Arabidopsis seedlings, and we also investigated the changes of ATP in the chloroplast and cytoplasm during greening by using a fluorescent protein sensor (Ateam 1.03-nD/nA) based on fluorescence resonance energy transfer (FRET) and the effects of NO on the changes of ATP content. The results showed that the content of NO, chlorophyll, and ATP in the chloroplast and cytoplasm increased with the increase of greening time. L-NAME, an inhibitor of NO, not only decreased the accumulation of chlorophyll content but also reduced the ATP content in the chloroplast and cytoplasm during the greening of Arabidopsis seedlings. Therefore, these experiments indicate that the accumulation of chlorophyll and changes of ATP during greening of etiolated Arabidopsis seedlings are mediated by nitric oxide. [ABSTRACT FROM AUTHOR]

In the present work, treatment with AMP-PCP (ß,-methyleneadenosine-5'-triphosphate - a competitive inhibitor of the extracellular ATP pool) or apyrase (an ATP-degrading enzyme) decreased the PSII operating efficiency (FPSII), photochemical quenching (qp), and maximum quantum efficiency of PSII photochemistry (Fv/Fm) of Arabidopsis leaves illuminated with high light intensity. Mutation of extracellular ATP receptor, DORN1, also caused decreases of FPSII, qp, and Fv/Fm when the leaves were exposed to high light. Either the treatment with AMP-PCP and apyrase or the mutation in DORN1 increased the salicylic acid content in the illuminated leaves. Salicylic acid deficiency in NahG transgenic mutant made the PSII photochemistry more sensitive to AMP-PCP or apyrase. These results indicate that extracellular ATP depletion can affect the PSII photochemistry, whereas salicylic acid can relieve this effect. [ABSTRACT FROM AUTHOR]

Sulfur dioxide is a widespread air pollutant and it also acts as a signaling molecule in various processes in mammals. However, the role of SO2 in programmed cell death (PCD) in plants is unclear. Here we studied the role of SO2 in gibberellin (GA)-treated wheat aleurone layers. The results showed that 100 μM SO2 donor (NaHSO3/Na2SO3) could effectively delay PCD and inhibit the coalescence of small protein storage vacuoles (PSVs) in aleurone cells treated with GA. Also, SO2 could reduce the accumulation of hydrogen peroxide and superoxide anion in GA-treated aleurone layers. In this process, SO2 could sustain higher activities of catalase, guaiacol peroxidase, ascorbate peroxidase, and superoxide dismutase and lower activities of lipoxygenase and polyphenol oxidase by comparing with GA alone. In addition, an induction of endogenous H2S and NO was observed in SO2-treated aleurone layers. The application of NO scavenger cPTIO could accelerate PCD in SO2 or H2S treated aleurone cells, suggesting that NO alleviated PCD by acting downstream of SO2 and H2S. In conclusion, these results imply that SO2 could delay PCD in GA-treated wheat aleurone layers by enhancing cellular antioxidative capacity, and H2S/NO signals act downstream of SO2. [ABSTRACT FROM AUTHOR]

Extracellular ATP (eATP) has been considered as an important extracellular compound to mediate several physiological processes in plant cells. We investigated the effects of eATP on chlorophyll (Chl) fluorescence characteristics of kidney bean ( Phaseolus vulgaris) leaves. Treatment with exogenous ATP at 1 mM showed no significant effect on the maximal photochemical efficiency of PSII. However, the treatment significantly enhanced the values of the PSII operating efficiency (Φ), rate of photosynthetic electron transport through PSII (ETR), and photochemical quenching (q), while the values of the nonphotochemical quenching (q) and quantum yield of regulated energy dissipation of PSII (Y) significantly decreased. Our observations indicated that eATP stimulated the PSII photochemistry in kidney bean leaves. Similarly, the treatment with exogenous Ca or HO at 1 mM caused also the significant increase in Φ, q, and ETR and the significant decrease in q and Y. LaCl (an inhibitor of Ca channels) and dimethylthiourea (a scavenger of HO) abolished the effects of exogenous ATP. The results suggest that the role of eATP in enhancing the PSII photochemistry could be related to a Ca or HO signaling pathway. [ABSTRACT FROM AUTHOR]

After exposing one half of a low light-adapted kidney bean ( Phaseolus vulgaris) leaf to high light, parameters of chlorophyll (Chl) a fluorescence, such as PSII operating efficiency, PSII maximum efficiency under light, and photochemical quenching, decreased in the opposite half of the same leaf, whereas the capacity of the cyanide-resistant respiratory pathway significantly increased. When one half of the low light-adapted leaf was exposed to low light, the opposite half pretreated with 1 mM salicylhydroxamic acid (SHAM, an inhibitor of the cyanide-resistant respiratory pathway) did not exhibit significant changes in the Chl fluorescence values compared with the without SHAM pretreatment. However, after exposing one half of the low light-adapted leaf to high light, the opposite half pretreated with 1 mM SHAM showed lower Chl fluorescence values than that without SHAM pretreatment. Our results indicate that partial exposure of the low light-adapted leaf to high light can impose a systemic stress on the PSII photochemistry. The enhanced capacity of the cyanide-resistant respiratory pathway may be involved in the maintenance of the photosynthetic performance in the leaf tissues experiencing high light-induced systemic stress. [ABSTRACT FROM AUTHOR]

Extracellular ATP (eATP) has been considered as signalling compound to mediate several physiological processes. Here we show that eATP played a role in alleviating the salicylic acid (SA)-induced inhibition of cell viability and respiration in tobacco ( Nicotiana tabacum L. cv. Bright Yellow-2) suspension cells. Exogenous SA at higher concentrations (0.05, 0.1, 0.3, 0.5, or 0.7 mM) caused a significant reduction in respiratory O uptake or cell viability. The addition of exogenous ATP alleviated the SA-induced reductions in cell viability and respiration, but the effect was dependent on the concentrations of either exogenous SA or ATP. Further study shows that the alleviative effects of exogenous ATP were abolished by the addition of GdCl (an inhibitor of Ca channels) or EGTA (a Ca chelator). These results suggest that this role of extracellular ATP could be related to a Ca signalling pathway. [ABSTRACT FROM AUTHOR]

The present work showed that spider mite-infested leaves placed in the light were more attractive to predatory mites than the infested leaves placed in the dark; furthermore, an increase in the light intensity enhanced this attractiveness. However, the increase of the light intensity did not change the attractiveness of the uninfested leaves to predatory mites. The capacity of cyanide-resistant respiration and the photosynthetic rates of both the infested and uninfested leaves increased with increasing light intensities, whereas the photosystem (PS) II chlorophyll (Chl) fluorescence decreased. The increase of the capacity of cyanide-resistant respiration in the infested leaves was more dramatic than that in the uninfested leaves, whereas the values of photosynthetic rates and Chl fluorescence were lower in the infested leaves than those in the uninfested leaves. Treatment of the infested and uninfested leaves with 1 mM salicylhydroxamic acid (SHAM, an inhibitor of cyanide-resistant respiration) decreased photosynthetic rates and caused further reductions in PSII fluorescence, especially under a higher light intensity. In contrast, the effects of SHAM on PSII fluorescence parameters and photosynthetic rates of the infested leaves were more dramatic than on those of the uninfested leaves. The treatment with SHAM did not significantly change the attractiveness of the infested or uninfested leaves to the predatory mites under all of the light intensities tested. These results indicated that cyanide-resistant respiration was not directly associated with the light-induced attraction of predators to plants, but it could play a role in the protection of photosynthesis. Such role might become relatively more important when photosynthesis is impaired by herbivores infestation. [ABSTRACT FROM AUTHOR]