Glyphosate Application Causes Physiological Perturbations in Amino Acid Profiles of Palmer amaranth- A Study of Susceptible and Resistant Biotypes of Amaranthus palmeri

Glyphosate is the most widely used herbicide in the world. It is used to control perennial grasses and weeds having broad leaves. Glyphosate works by inhibiting the plant specific enzyme 5-enolpyruvylshikimate-3-phospate synthase that catalyzes the conversion of shikimic acid to chorismate, which serves as the precursor to production of aromatic amino acids, namely tyrosine, phenylalanine and tryptophan

Warming and elevated CO\u3csub\u3e2\u3c/sub\u3e alter the suberin chemistry in roots of photosynthetically divergent grass species

A majority of soil carbon (C) is either directly or indirectly derived from fine roots, yet roots remain the least understood component of the terrestrial carbon cycle. The decomposability of fine roots and their potential to contribute to soil C is partly regulated by their tissue chemical composition. Roots rely heavily on heteropolymers such as suberins, lignins and tannins to adapt to various environmental pressures and to maximize their resource uptake functions. Since the chemical construction of roots is partly shaped by their immediate biotic/abiotic soil environments, global changes that perturb soil resource availability and plant growth could potentially alter root chemistry, and hence the decomposability of roots. However, the effect of global change on the quantity and composition of root heteropolymers are seldom investigated. We examined the effects of elevated CO2 and warming on the quantity and composition of suberin in roots of Bouteloua gracilis (C4) and Hesperostipa comata (C3) grass species at the Prairie Heating and CO2 Enrichment (PHACE) experiment at Wyoming, USA. Roots of B. gracilis exposed to elevated CO2 and warming had higher abundances of suberin and lignin than those exposed to ambient climate treatments. In addition to changes in their abundance, roots exposed to warming and elevated CO2 had higher ω-hydroxy acids compared to plants grown under ambient conditions. The suberin content and composition in roots of H. comata was less responsive to climate treatments. In H. comata, α,ω-dioic acids increased with the main effect of elevated CO2, whereas the total quantity of suberin exhibited an increasing trend with the main effect of warming and elevated CO2. The increase in suberin content and altered composition could lower root decomposition rates with implications for root-derived soil carbon under global change. Our study also suggests that the climate change induced alterations in species composition will further mediate potential suberin contributions to soil carbon pools

Shade and Fertilizer Affects Yield and Quality in a Clonal Plantation of Yaupon Holly

Yaupon holly (Ilex vomitoria Ait.) is the only native American source of caffeinated tea and the small amounts of tea product that is available is currently wild-collected from diverse populations. A clonal field plantation of yaupon was grown under shading and fertilizer treatments and harvested three times in one season to observe changes in yield and phytochemistry. The June and September harvest produced more mass than the July harvest for all treatments. Shading and fertility had interactive effects on increasing fresh mass of the pooled annual harvest, whereas the providing 30% shade and increased fertilizer application (from 567 to 1163 mg/N plant) raised yield 58%. Fertility of 1163 mg/N per plant with 60% shade increased yield another 13% to approximately 1070 kg/ha. This experimental plantation contained 467 plants per ha and was at about half the density of commercial fields (882 plants per ha). Leaves were smaller in July and larger in June and September. Shade greatly increased the leaf size and water content. Caffeine content increased with leaf size over the duration of the experimental treatments and 60% shade treatments in September produced the highest caffeine content (1.21 ± 0.17% of dry mass). In general alkaloids were promoted by shading, and phenylpropanoids were promoted by bright light. This report from one season of observation showed that genetically uniform yaupon holly plantations were manipulated for yield and quality using shade and fertilizer

Climate Influences the Content and Chemical Composition of Foliar Tannins in Green and Senesced Tissues of \u3ci\u3eQuercus rubra\u3c/i\u3e

Environmental stresses not only influence production of plant metabolites but could also modify their resorption during leaf senescence. The production-resorption dynamics of polyphenolic tannins, a class of defense compound whose ecological role extends beyond tissue senescence, could amplify the influence of climate on ecosystem processes. We studied the quantity, chemical composition, and tissue-association of tannins in green and freshly-senesced leaves of Quercus rubra exposed to different temperature (Warming and No Warming) and precipitation treatments (Dry, Ambient, Wet) at the Boston-Area Climate Experiment (BACE) in Massachusetts, USA. Climate influenced not only the quantity of tannins, but also their molecular composition and cell-wall associations. Irrespective of climatic treatments, tannin composition in Q. rubra was dominated by condensed tannins (CTs, proanthocyanidins). When exposed to Dry and Ambient*Warm conditions, Q. rubra produced higher quantities of tannins that were less polymerized. In contrast, under favorable conditions (Wet), tannins were produced in lower quantities, but the CTs were more polymerized. Further, even as the overall tissue tannin content declined, the content of hydrolysable tannins (HTs) increased under Wet treatments. The molecular composition of tannins influenced their content in senesced litter. Compared to the green leaves, the content of HTs decreased in senesced leaves across treatments, whereas the CT content was similar between green and senesced leaves in Wet treatments that produced more polymerized tannins. The content of total tannins in senesced leaves was higher in Warming treatments under both dry and ambient precipitation treatments. Our results suggest that, though climate directly influenced the production of tannins in green tissues (and similar patterns were observed in the senesced tissue), the influence of climate on tannin content of senesced tissue was partly mediated by the effect on the chemical composition of tannins. These different climatic impacts on leaves over the course of a growing season may alter forest dynamics, not only in decomposition and nutrient cycling dynamics, but also in herbivory dynamics

Litters of photosynthetically divergent grasses exhibit differential metabolic responses to warming and elevated CO\u3csub\u3e2\u3c/sub\u3e

Climatic stress such as warming would alter physiological pathways in plants leading to changes in tissue chemistry. Elevated CO2 could partly mitigate warming induced moisture stress, and the degree of this mitigation may vary with plant functional types. We studied the composition of structural and non-structural metabolites in senesced tissues of Bouteloua gracilis (C4) and Pascopyrum smithii (C3) at the Prairie Heating and CO2 Enrichment experiment, Wyoming, USA. We hypothesized that P. smithii and B. gracilis would respond to unfavorable global change factors by producing structural metabolites and osmoregulatory compounds that are necessary to combat stress. However, due to the inherent variation in the tolerance of their photosynthetic pathways to warming and CO2, we hypothesized that these species will exhibit differential response under different combinations of warming and CO2 conditions. Due to a lower thermo-tolerance of the C4 photosynthesis we expected B. gracilis to exhibit a greater metabolic response under warming with ambient CO2 (cT) and P. smithii to exhibit a similar response under warming combined with elevated CO2 (CT). Our hypothesis was supported by the differential response of structural compounds in these two species, where cT increased the content of lignin and cuticular-matrix in B. gracilis. In P. smithii a similar response was observed in plants exposed to CT, possibly due to the partial alleviation of moisture stress.With warming, the total cell-wall bound phenolic acids that cross link polysaccharides to lignins increased in B. gracilis and decreased in P. smithii, indicating a potentially adaptive response of C4 pathway to warming alone. Similarly, in B. gracilis, extractable polar metabolites such as sugars and phenolic acids increased with the main effect of warming. Conversely, in P. smithii, only sugars showed a higher abundance in plants exposed to warming treatments indicating that warming alone might be metabolically too disruptive for the C3 photosynthetic pathway. Here we show for the first time, that along with traditionally probed extractable metabolites, warming and elevated CO2 differentially influence the structural metabolites in litters of photosynthetically divergent grass species. If these unique metabolite responses occur in other species of similar functional types, this could potentially alter carbon cycling in grasslands due to the varying degradability of these litters

Litters of photosynthetically divergent grasses exhibit differential metabolic responses to warming and elevated CO\u3csub\u3e2\u3c/sub\u3e

Climatic stress such as warming would alter physiological pathways in plants leading to changes in tissue chemistry. Elevated CO2 could partly mitigate warming induced moisture stress, and the degree of this mitigation may vary with plant functional types. We studied the composition of structural and non-structural metabolites in senesced tissues of Bouteloua gracilis (C4) and Pascopyrum smithii (C3) at the Prairie Heating and CO2 Enrichment experiment, Wyoming, USA. We hypothesized that P. smithii and B. gracilis would respond to unfavorable global change factors by producing structural metabolites and osmoregulatory compounds that are necessary to combat stress. However, due to the inherent variation in the tolerance of their photosynthetic pathways to warming and CO2, we hypothesized that these species will exhibit differential response under different combinations of warming and CO2 conditions. Due to a lower thermo-tolerance of the C4 photosynthesis we expected B. gracilis to exhibit a greater metabolic response under warming with ambient CO2 (cT) and P. smithii to exhibit a similar response under warming combined with elevated CO2 (CT). Our hypothesis was supported by the differential response of structural compounds in these two species, where cT increased the content of lignin and cuticular-matrix in B. gracilis. In P. smithii a similar response was observed in plants exposed to CT, possibly due to the partial alleviation of moisture stress.With warming, the total cell-wall bound phenolic acids that cross link polysaccharides to lignins increased in B. gracilis and decreased in P. smithii, indicating a potentially adaptive response of C4 pathway to warming alone. Similarly, in B. gracilis, extractable polar metabolites such as sugars and phenolic acids increased with the main effect of warming. Conversely, in P. smithii, only sugars showed a higher abundance in plants exposed to warming treatments indicating that warming alone might be metabolically too disruptive for the C3 photosynthetic pathway. Here we show for the first time, that along with traditionally probed extractable metabolites, warming and elevated CO2 differentially influence the structural metabolites in litters of photosynthetically divergent grass species. If these unique metabolite responses occur in other species of similar functional types, this could potentially alter carbon cycling in grasslands due to the varying degradability of these litters

Rapid Screening of Ellagitannins in Natural Sources via Targeted Reporter Ion Triggered Tandem Mass Spectrometry

Complex biomolecules present in their natural sources have been difficult to analyze using traditional analytical approaches. Ultrahigh-performance liquid chromatography (UHPLC-MS/MS) methods have the potential to enhance the discovery of a less well characterized and challenging class of biomolecules in plants, the ellagitannins. We present an approach that allows for the screening of ellagitannins by employing higher energy collision dissociation (HCD) to generate reporter ions for classification and collision-induced dissociation (CID) to generate unique fragmentation spectra for isomeric variants of previously unreported species. Ellagitannin anions efficiently form three characteristic reporter ions after HCD fragmentation that allows for the classification of unknown precursors that we call targeted reporter ion triggering (TRT). We demonstrate how a tandem HCD-CID experiment might be used to screen natural sources using UHPLC-MS/MS by application of 22 method conditions from which an optimized data-dependent acquisition (DDA) emerged. The method was verified not to yield false-positive results in complex plant matrices. We were able to identify 154 non-isomeric ellagitannins from strawberry leaves, which is 17 times higher than previously reported in the same matrix. The systematic inclusion of CID spectra for isomers of each species classified as an ellagitannin has never been possible before the development of this approach