Plant biotechnology: ecological case studies on herbicide resistance

The emerging field of molecular ecology aims to improve the ecological predictability of transgenic crop plants. The most widely cultivated lines are Roundup-Ready plants, which are genetically modified to be resistant to the broad-spectrum herbicide glyphosate. Recent publications demonstrate two ecological effects that were not anticipated: the widespread emergence of glyphosate-resistant weed biotypes and the formation of a metabolic herbicidal residue. Both effects appear to be due to the increased use of glyphosate rather than the genetic modification in the transgenic crop plant. With one prominent exception, opinions collected from the literature point towards a certain degree of resistance mismanagement and an inadequate testing of the ecological effects of extensive glyphosate use.     

Declining Amazon biomass due to deforestation and subsequent degradation losses exceeding gains

In the Amazon, deforestation and climate change lead to increased vulnerability to forest degradation, threatening its existing carbon stocks and its capacity as a carbon sink. We use satellite L-Band Vegetation Optical Depth (L-VOD) data that provide an integrated (top-down) estimate of biomass carbon to track changes over 2011–2019. Because the spatial resolution of L-VOD is coarse (0.25°), it allows limited attribution of the observed changes. We therefore combined high-resolution annual maps of forest cover and disturbances with biomass maps to model carbon losses (bottom-up) from deforestation and degradation, and gains from regrowing secondary forests. We show an increase of deforestation and associated degradation losses since 2012 which greatly outweigh secondary forest gains. Degradation accounted for 40% of gross losses. After an increase in 2011, old-growth forests show a net loss of above-ground carbon between 2012 and 2019. The sum of component carbon fluxes in our model is consistent with the total biomass change from L-VOD of 1.3 Pg C over 2012-2019. Across nine Amazon countries, we found that while Brazil contains the majority of biomass stocks (64%), its losses from disturbances were disproportionately high (79% of gross losses). Our multi-source analysis provides a pessimistic assessment of the Amazon carbon balance and highlights the urgent need to stop the recent rise of deforestation and degradation, particularly in the Brazilian Amazon.     

International Code of Phytosociological Nomenclature. 4th edition

The fourth edition of the International Code of Phytosociological Nomenclature (ICPN) was prepared by the Steering Committee of the IAVS Working Group for Phytosociological Nomenclature (GPN). The edition consists of 14 Definitions, 7 Principles, 53 Articles, and 7 Appendices. When compared with the previous edition, the main amendments are: (a) the acceptance of electronic publications (Art. 1); (b) the introduction of binding decisions (Definition XIV, Principle II, Articles 1, 2b, 3c, 29b, 40, 42, 44, Appendices 6 and 7); (c) the mandatory use of the English or Latin terminology for syntaxonomic novelties (Definition II, Principle II, Articles 3d and 3i); (d) the introduction of autonyms for the main ranks when the corresponding secondary ranks are created (Articles 13b and 24); (e) the automatic correction of the taxon names (name-giving taxa) used in the names of syntaxa in accordance with the International Code of Nomenclature for algae, fungi, and plants (ICN) (Article 44); (f) the possibility to mutate the name of a syntaxon in using other correct, alternative names for the name-giving taxa (Article 45); (g) the introduction of inadequate names, a new category of rejected names (Definition V, Articles 43 through 45); and (h) the introduction of a conserved type (Definition XIII, Article 53). The fourth edition of ICPN was approved by the GPN on 25 May 2019 and becomes effectively binding on 1 January 2021.     

Antiplasmodial and Cytotoxic Activities of Extract and Compounds from Ozoroa obovata (Oliv.) R. & A. Fern. var. obovata

Ozoroa obovata (Oliv.) R. & A. Fern. var. obovata found in KwaZulu-Natal in South Africa was investigated for phytochemical constituents, and for antiplasmodial and cytotoxic effects. The plant leaves were collected from the University of KwaZulu-Natal (UKZN) arboretum on the Pietermaritzburg Campus, in March 2019. The inhibitory activity against 3D7 Plasmodium falciparum was determined using the parasite lactate dehydrogenase (pLDH) assay and cytotoxicity against HeLa cells was evaluated using the resazurin assay. The bioactive compounds were isolated by chromatographic purification and their structures were established with spectroscopic and spectrometric techniques. The plant leaf extract displayed significant antiplasmodial activity at 50 μg/mL and was also cytotoxic against HeLa cells. Chromatographic purification of the extract led to the isolation of two biflavonoids, four flavonoid glycosides, a steroid glycoside, and a megastigmene derivative. The compounds displayed antiplasmodial and antiproliferative activities at 50 μg/mL but the activity was substantially reduced at 10 μg/mL. The activities and compounds are being reported in O. obovata for the first time.     

Six minutes to promote change: People,not facts,alter students' perceptions on climate change

Anthropogenic climate change threatens the structure and function of ecosystems throughout the globe, but many people are still skeptical of its existence. Traditional “knowledge deficit model” thinking has suggested that providing the public with more facts about climate change will assuage skepticism. However, presenting evidence contrary to prior beliefs can have the opposite effect and result in a strengthening of previously held beliefs, a phenomenon known as biased assimilation or a backfire effect. Given this, strategies for effectively communicating about socioscientific issues that are politically controversial need to be thoroughly investigated. We randomly assigned 184 undergraduates from an environmental science class to one of three experimental conditions in which we exposed them to short videos that employed different messaging strategies: (a) an engaging science lecture, (b) consensus messaging, and (c) elite cues. We measured changes in student perceptions of climate change across five constructs (content knowledge, acceptance of scientific consensus, perceived risk, support for action, and climate identity) before and after viewing videos. Consensus messaging outperformed the other two conditions in increasing student acceptance of the scientific consensus, perceived risk of climate change, and climate identity, suggesting this may be an effective strategy for communicating the gravity of anthropogenic climate change. Elite cues outperformed the engaging science lecture condition in increasing student support for action on climate, with politically conservative students driving this relationship, suggesting that the messenger is more important than the message if changing opinions about the necessity of action on climate change is the desired outcome. Relative to the other conditions, the engaging science lecture did not support change in students'' perceptions on climate, but appealing to student respect for authority produced positive results. Notably, we observed no decline in students'' acceptance of climate science, indicating that none of the conditions induced a backfire effect.     

Microscopic Observation on the Development of Puccinia striiformis in the Spike and Stem of Wheat

The majority of germ tubes of the pathotype CYR32 of Puccinia striiformis f.sp. tritici formed on the surface of spike organs of the susceptible wheat cv. Suwon 11 penetrated through the stomatal pore, only a few germ tubes formed small appressoria over the stomata. In the lemma, palea and glume, the stripe rust fungus spread between the parenchyma cells close to the inner epidermal layer, but the fungus did not develop between the thick‐walled cells near the outer epidermal layer of these organs. In the awn and stem, spread of the stripe rust was confined to the intercellular spaces of the chlorophyll parenchyma, beneath the invaded stomatal pore of the epidermis and the urediniospores to be released disrupted the epidermis. In the caryopsis, the spread of hyphae was restricted to the intercellular spaces of the pericarp cells.