Molecular bases for the stronger plastic response to high nitrate in the invasive plant Xanthium strumarium compared with its native congener.

MAIN CONCLUSION: High expressions of nitrate use and photosynthesis-related transcripts contribute to the stronger plasticity to high nitrate for the invader relative to its native congener, which may be driven by hormones. Strong phenotypic plasticity is often considered as one of the main mechanisms underlying exotic plant invasions. However, few studies have been conducted to investigate the related molecular mechanisms. Here, we determined the differences in the plastic responses to high nitrate between the invasive plant X. strumarium and its native congener, and the molecular bases by transcriptome analysis and quantitative real-time PCR validation. Our results showed that the invader had higher plasticity of growth, nitrogen accumulation and photosynthesis in responses to high nitrate than its native congener. Compared with its congener, more N utilization-related transcripts, including nitrate transporter 1/peptide transporter family 6.2 and nitrate reductase 1, were induced by high nitrate in the root of X. strumarium, improving its N utilization ability. More transcripts coding for photosynthetic antenna proteins were also induced by high nitrate in the shoot of X. strumarium, enhancing its photosynthesis. Hormones may be involved in the regulation of the plastic responses to high nitrate in the two species. Our study contributes to understanding the molecular mechanisms underlying the stronger plasticity of the invader in responses to high nitrate, and the potential function of plant hormones in these processes, providing bases for precise control of invasive plants using modern molecular techniques.

Feeding Laying Ducks Eucommia ulmoides oliv. Leaves Increases the n-3 Fatty Acids Content and Decreases the n-6: n-3 PUFA Ratio in Egg Yolk without Affecting Laying Performance or Egg Quality.

The objective was to determine the effects of supplementing duck diets with Eucommia ulmoides oliv. leaf powder (EUL). Laying ducks (n = 480) were randomly allocated into 4 experimental treatments and fed diets containing 0, 1, 2, or 4% EUL. Dietary inclusion of EUL had no effect (p > 0.05) on laying performance or egg quality, but linearly increased (p < 0.05) total plasma protein, globulin, and HDL-C concentrations with concurrent reductions (p < 0.05) in plasma concentrations of cholesterol and LDL-C. Eggs laid by ducks receiving EUL had yolks with linearly higher phenolic concentrations (p < 0.05) but lower cholesterol concentrations (p < 0.05). EUL supplementation in duck diets significantly reduced n-6: n-3 PUFA ratio by enriching n-3 fatty acids in yolks (p < 0.05) with no changes in n-6 PUFA (p >0.05).

Rapid prediction method of α-Glycosidase inhibitory activity of Coreopsis tinctoria extract from different habitats by near infrared spectroscopy.

α-Glucosidase is one of the main enzymes causing elevated blood glucose, and Coreopsis tinctoria extract can be used as a natural inhibitor of α-Glucosidase. Therefore, a new method was proposed for predicting the inhibitory activity on α-Glucosidase of Coreopsis tinctoria extract based on near infrared spectroscopy. The absorbance of the inhibitory system was measured by ultraviolet spectroscopy, which was used to study the inhibitory activity on a-glucosidase of Coreopsis tinctoria extract. The near infrared spectra of the solid samples were collected. By selecting spectral preprocessing and optimizing spectral bands, a rapid prediction model of the inhibitory activity was established by partial least squares regression. The root mean square error of cross-validation (RMSECV), correlation coefficient (R) value and the ratio of prediction to deviation (RPD) value were used as indicators of the evaluation model. The near infrared spectrum model was established by combining the best spectral preprocessing of the continuous wavelet transform (CWT) and the best spectral band. The root mean square error of cross-validation (RMSECV) of this model was 0.815%, the correlation coefficient (R) value was 0.942, and the ratio of prediction to deviation (RPD) was 3.0. The root mean square error of prediction (RMSEP) of the model by prediction set was 0.819%, the correlation coefficient (R) value was 0.950, and the RPD was 3.2. The model shows that the fitting relationship between the predicted inhibition value and the reference inhibition value of the near infrared spectral model is good. The results showed that there was a good correlation between near infrared spectroscopy and the inhibitory activity of Coreopsis tinctoria extract. Thus, the established model was robust and effective and could be used for rapid quantification of α-Glucosidase inhibitory activity. The prediction method is simple and rapid, and can be extended to study the inhibition of other medicinal plants.

Pyrrole alkaloids from Solanum rostratum and their chemical defense function against Henosepilachna vigintioctomaculata.

Three pairs of novel enantiomeric pyrrole alkaloids (1a/1b, 2a/2b, 3a/3b) were isolated from the leaves of Solanum rostratum and their structures were determined via NMR analyses and ECD calculation. All the enantiomers displayed different levels of antifeedant and growth-inhibitory activities against Henosepilachna vigintioctomaculata (a noxious herbivore for Solanaceae), especially 1a and 2a. Interestingly, the results showed enantioselectivity, in which that the pyrrole alkaloids with R configuration at C-2' showed stronger chemical defense function than their enantiomers.

Severe pantothenic acid deficiency induces alterations in the intestinal mucosal proteome of starter Pekin ducks.

BACKGROUND: Pantothenic acid deficiency (PAD) results in growth depression and intestinal hypofunction of animals. However, the underlying molecular mechanisms remain to be elucidated. Mucosal proteome might reflect dietary influences on physiological processes. RESULTS: A total of 128 white Pekin ducks of one-day-old were randomly assigned to two groups, fed either a PAD or a pantothenic acid adequate (control, CON) diet. After a 16-day feeding period, two ducks from each replicate were sampled to measure plasma parameters, intestinal morphology, and mucosal proteome. Compared to the CON group, high mortality, growth retardation, fasting hypoglycemia, reduced plasma insulin, and oxidative stress were observed in the PAD group. Furthermore, PAD induced morphological alterations of the small intestine indicated by reduced villus height and villus surface area of duodenum, jejunum, and ileum. The duodenum mucosal proteome of ducks showed that 198 proteins were up-regulated and 223 proteins were down-regulated (> 1.5-fold change) in the PAD group compared to those in the CON group. Selected proteins were confirmed by Western blotting. Pathway analysis of these proteins exhibited the suppression of glycolysis and gluconeogenesis, fatty acid beta oxidation, tricarboxylic acid cycle, oxidative phosphorylation, oxidative stress, and intestinal absorption in the PAD group, indicating impaired energy generation and abnormal intestinal absorption. We also show that nine out of eleven proteins involved in regulation of actin cytoskeleton were up-regulated by PAD, probably indicates reduced intestinal integrity. CONCLUSION: PAD leads to growth depression and intestinal hypofunction of ducks, which are associated with impaired energy generation, abnormal intestinal absorption, and regulation of actin cytoskeleton processes. These findings provide insights into the mechanisms of intestinal hypofunction induced by PAD.

Effects of the invasive plant Xanthium strumarium on diversity of native plant species: A competitive analysis approach in North and Northeast China.

Xanthium strumarium is native to North America and now has become one of the invasive alien species (IAS) in China. In order to detect the effects of the invader on biodiversity and evaluate its suitable habitats and ecological distribution, we investigated the abundance, relative abundance, diversity indices, and the number of the invasive and native plants in paired invaded and non-invaded quadrats in four locations in North and Northeast China. We also analyzed the effects of monthly mean maximum and minimum temperatures, relative humidity (%), and precipitations (mm). Strong positive significant (P < 0.01) correlation and maximum interspecific competition (41%) were found in Huailai between invaded and non-invaded quadrats. Shannon's Diversity Index showed that non-invaded plots had significantly (P < 0.05) more diversified species than invaded ones. The significant (P < 0.05) Margalef's Richness Index was found in Huailai and Zhangjiakou in non-invaded recorded heterogeneous nature of plant communities. Similarly, significant (P < 0.05) species richness found in Huailai and Zhangjiakou in non-invaded quadrats compared to invaded ones. Maximum evenness of Setaria feberi (0.47, 0.37), Seteria viridis (0.43) found in Fushun and Zhangjiakou recorded more stable in a community compared to other localities. Evenness showed positive relationship of Shannon Entropy within different plant species. The higher dissimilarity in plant communities found in Huailai (87.06%) followed by Yangyuan (44.43%), Zhangjiakou (40.13%) and Fushun (29.02%). The significant (P < 0.01) value of global statistics R (0.943/94.3%) showed high species diversity recorded in Huailai followed by Zhangjiakou recorded by non-metric multidimensional scaling and analysis of similarity between invaded and non-invaded plots. At the end it was concluded that the diversity indices reduced significantly (P < 0.05) in invaded quadrats indicated that native plant species become less diverse due to X. strumarium invasion. The degrees of X. strumarium invasion affected on species richness resulted to reduce diversity indices significantly in invaded quadrats.

Effects of pantothenic acid on growth performance and antioxidant status of growing male white Pekin ducks.

An experiment was conducted to investigate the effects of dietary pantothenic acid levels on growth performance, carcass traits, pantothenic acid status, and antioxidant status of male white Pekin ducks from 15 to 42 D of age and to evaluate the requirement of this vitamin for growing ducks. Different levels pantothenic acid (0, 2, 4, 6, 8, and 10 mg/kg) were supplemented to a corn-soy isolate protein basal diet to produce 6 dietary treatments with different analyzed total pantothenic acid levels (4.52, 6.44, 8.37, 9.88, 12.32, and 14.61 mg/kg). A total of 240 15-day-old male white Pekin ducks were allotted to 6 dietary treatments with 8 replicate pens of 5 birds per pen. At 42 D of age, growth performance, carcass traits, tissue pantothenic acid concentrations, and antioxidant status of white Pekin ducks were examined. Significant effects of dietary pantothenic acid on BW, average daily weight gain (ADG), plasma, and liver pantothenic acid concentrations were observed (P < 0.05) but not carcass traits. The growing ducks fed the basal diet without pantothenic acid supplementation had the lowest BW, ADG, plasma, and liver pantothenic acid content among all ducks (P < 0.05). In addition, the ducks fed the basal diet without pantothenic acid supplementation showed the lowest antioxidant capacity indicated by greatest plasma malondialdehyde content and lowest liver total antioxidant capacity (P < 0.05). And, these criteria responded linearly as dietary pantothenic acid levels increased (P < 0.05). These results indicated that dietary pantothenic acid supplementation improved growth performance and antioxidant status of the growing ducks. In accordance with the broken-line model, the pantothenic acid requirements (based on dietary total pantothenic acid) of male white Pekin ducks from 15 to 42 D of age for BW, ADG, and plasma and liver pantothenic acid contents were 10.18, 10.27, 12.06, and 10.79 mg/kg, respectively.

Secondary Metabolites from Solanum rostratum and Their Antifeedant Defense Mechanisms against Helicoverpa armigera.

Solanum rostratum is a worldwide malignant invasive weed, causing serious harm to the ecological environment and biodiversity. Strong chemical defense against herbivorous insects is supposed to be one of the successful invasive mechanisms of this exotic plant. However, the real defense components and their action mechanisms and distributions are still unknown. To address these problems, we bioassay-guided isolated compounds from the aerial part of S. rostratum and determined their structures using high-resolution electrospray ionization mass spectrometry, nuclear magnetic resonance, and electronic circular dichroism calculation. One new and seven known compounds were identified, and all of the isolates exhibited different levels of antifeedant activities, especially compounds 1 and 4. Consistently, compounds 1 and 4 displayed potent inhibitory effects on antifeedant-related enzymes (AchE and CarE). The action mechanisms of active compounds 1 and 4 were revealed by molecular docking and molecular dynamic simulation studies. Furthermore, the distributions of the active compounds in leaves, stems, and flowers were also analyzed by liquid chromatography-mass spectrometry.

Higher photosynthesis, nutrient- and energy-use efficiencies contribute to invasiveness of exotic plants in a nutrient poor habitat in northeast China.

The roles of photosynthesis-related traits in invasiveness of introduced plant species are still not well elucidated, especially in nutrient-poor habitats. In addition, little effort has been made to determine the physiological causes and consequences of the difference in these traits between invasive and native plants. To address these problems, we compared the differences in 16 leaf functional traits related to light-saturated photosynthetic rate (Pmax ) between 22 invasive and native plants in a nutrient-poor habitat in northeast China. The invasive plants had significantly higher Pmax , photosynthetic nitrogen- (PNUE), phosphorus- (PPUE), potassium- (PKUE) and energy-use efficiencies (PEUE) than the co-occurring natives, while leaf nutrient concentrations, construction cost (CC) and specific leaf area were not significantly different between the invasive and native plants. The higher PNUE contributed to higher Pmax for the invasive plants, which in turn contributed to higher PPUE, PKUE and PEUE. CC changed independently with other traits such as Pmax , PNUE, PPUE, PKUE and PEUE, showing two trait dimensions, which may facilitate acclimation to multifarious niche dimensions. Our results indicate that the invasive plants have a superior resource-use strategy, i.e. higher photosynthesis under similar resource investments, contributing to invasion success in the barren habitat.

[Effects of soil phosphorus level on morphological and photosynthetic characteristics of Ageratina adenophora and chromolaena odorata].

In this paper, a comparative study was made on the growth, morphology, biomass allocation, and photosynthesis of two invasive plant species Ageratina adenophora and Chromolaena odorata under five soil phosphorus levels, aimed to know how the test plant species acclimate to the changes of soil phosphorus level, evaluate which plant traits were associated with the invasiveness of the two species, and know whether the increased level of soil phosphorus could facilitate their invasion. The results showed that the two species had considerable phenotypic plasticity and ? phosphorus acclimation ability. At low phosphorus levels, their root mass ratio increased, which could enhance the nutrient capture ability, while at high phosphorus levels, their specific leaf area, maximum net photosynthetic rate, light saturation point, and chlorophyll and carotenoid contents per unit area were high, and the assimilative capacity and area increased, which could facilitate their carbon gain. A. adenophora had higher phosphorus acclimation ability than C. odorata. With the increase of phosphorous level, the relative growth rate, total biomass, branch number, leaf area index, and maximum net photosynthetic rate of the two species increased significantly, and most of the parameters were not decreased significantly under over-optimal phosphorus level. The two species could grow better under high phosphorus levels which were usually excessive and/or harmful for most native species, and enhanced soil phosphorus level might promote their invasion. At high phosphorus levels, the two invasive plant species might shade out native species through increasing their plant height, branch number, and leaf area index. The two species could maintain relatively high growth rate under high phosphorus levels in dry season when native plant species almost stopped growing. The ability that the invasive plant species could temporally use natural resources which native plant species could not use was also associated with their invasiveness.

[Photosynthesis and oxidative stress of leaves at different positions in Amomum villosum Lour].

Amomum villosum Lour. (Zingeraceae) is a perennial herb that occurs in the understory of tropical and subtropical forests, and is an important medicinal plant. A. villosum, native to Guangdong province, was introduced intentionally to Xishuangbanna, Yunnan province in 1963, and was planted under tropical rainforest. The income from planting A.villosum in rainforest is very important for minority in Xishuangbanna. But now A. villosum fruit yield has decreased greatly due to plant senescence. The senescence mechanism of A. villosum is not known clearly. A. villosum has only one main stem without branch. The leaf age can be estimated by its position at the stem. In this study we measured the variables of photosynthesis and chlorophyll fluorescence, the content of chlorophyll (Chl), Caroteniod, protein and malondialdehyde (MDA), and the activities of antioxidant enzymes of leaves at different positions in A.villosum. We want to know (1) the reasons of leaf photosynthesis decreasing during aging and senescence, and (2) the relationships between oxidative stress and aging/senescence. Leaf age, maximum net photosynthetic rates (P(max)), Chl and soluble protein content increased with the increase of leaf position in A. villosum. P(max) was biggest at the third leaf, while Chl and protein content reached its maximum values at the fifth leaf. They decreased at the 7th leaf, and began to decrease sharply at 9th leaf. MDA content was lower in the first to 7th leaves, and increased greatly at 9th leaf. AQY and F(v)/F(m) began to decrease at 9th leaf too. The results presented above suggested that the third to 5th leaves were mature leaves with vigorous physiological function, the 7th leaf was aging one, the 9th leaf began senescent, the 11th to 15th leaves were senescent. The decrease of Chl and protein content, and stomatal conductance might be the important reason of P(max) decreasing in aging and senescent leaves of A. villosum. NPQ, AQY, F(v)/F(m), Phi(PSII) and q(P) decreased with leaf aging and senescence, which indicated that thermal dissipation decreased, and photoinhibition of photosynthesis intensified. Furthermore, photodamage occurred at the late stage of senescence. But the reducing extent of AQY, F(v)/F(m), Phi(PSII) and q(P) was smaller than that of P(max), indicating that the electrons transported by PSII was more than those used by carbon assimilation. The excessive electron might induce production of reactive oxygen species (ROS). The excessive electron and then ROS were smaller in aging leaf than in senescent leaf. The ROS could be scavenged effectively by antioxidant enzymes and antioxidants in aging leaf, but not in senescent leaf, although the activities of antioxidant enzymes increased significantly. The ROS could results in membrane peroxidation, so MDA content increased, which could intensify leaf senescence further. The results above indicated that aging was not associated with oxidative stress, but senescence was in A. villosum.