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To learn the spatial and temporal distribution of Bt proteins in Bt maize leaves, Bt protein levels of Bt maize leaves and their corresponding non-transgenic lines were detected and analysed by the ELISA method. The results showed that Bt proteins were expressed in the leaves of Bt maize varieties during all periods of their growth, while no such Bt proteins were detected in the leaves of non-transgenic maize varieties. The range of leaf Bt proteins was 1.08∼5.81 µg.g−1 FW, which could effectively protect Bt maizes from the corn borer pest during their growth periods. Furthermore, the younger leaves of Bt maizes had significantly lower levels of Bt proteins than their older leaves. In most periods, Bt protein content of Bt maize leaves under drought stress was lower than that under normal growth conditions, but Bt protein content under nutrition stress was higher than that under normal growth conditions. The results provided a full pattern of the spatial and temporal distribution of Bt proteins in Bt maize leaves.

Coronavirus disease 2019 (COVID-19) caused by the SARS-CoV-2 virus has led to a global pandemic with a high spread rate and pathogenicity. Thus, with limited testing solutions, it is imperative to develop early-stage diagnostics for rapid and accurate detection of SARS-CoV-2 to contain the rapid transmission of the ongoing COVID-19 pandemic. In this regard, there remains little knowledge about the integration of the CRISPR collateral cleavage mechanism in the lateral flow assay and fluorophotometer. In the current study, we demonstrate a CRISPR/Cas12a-based collateral cleavage method for COVID-19 diagnosis using the Cas12a/crRNA complex for target recognition, reverse transcription loop-mediated isothermal amplification (RT-LAMP) for sensitivity enhancement, and a novel DNA capture probe-based lateral flow strip (LFS) or real-time fluorescence detector as the parallel system readout facility, termed CRICOLAP. Our novel approach uses a customized reporter that hybridizes an optimized complementary capture probe fixed at the test line for naked-eye result readout. The CRICOLAP system achieved ultra-sensitivity of 1 copy/µL in ~32 min by portable real-time fluorescence detection and ~60 min by LFS. Furthermore, CRICOLAP validation using 60 clinical nasopharyngeal samples previously verified with a commercial RT-PCR kit showed 97.5% and 100% sensitivity for S and N genes, respectively, and 100% specificity for both genes of SARS-CoV-2. CRICOLAP advances the CRISPR/Cas12a collateral cleavage result readout in the lateral flow assay and fluorophotometer, and it can be an alternative method for the decentralized field-deployable diagnosis of COVID-19 in remote and limited-resource locations. [ABSTRACT FROM AUTHOR]

Abstract The frequency and intensity of extreme weather events (e.g. flood, drought) are predicted to increase for the foreseeable future and it is expected that these will negatively impact upon agroecosystem functioning. Our understanding of how grassland ecosystems respond to extreme weather events occurring at different times of the year, however, is lacking. To better understand the seasonal response of grassland to flooding, we subjected an agricultural grassland to an 8-week extreme flood event at three different temperatures (5 °C-winter, 15 °C-spring/autumn and 25°C-summer) and then followed its subsequent recovery for 9 weeks after floodwater removal. We focused on key indicators of ecosystem functioning including primary production, nutrient cycling, greenhouse gas (GHG) emissions, ammonia (NH 3) volatilization, and soil microbial communities. The experiment used intact soil mesocosms (1 kg) with indigenous vegetation collected from a grassland with no previous history of flooding. Flooding reduced biomass production by 18% at 5 °C, 50% at 15 °C and 95% at 25 °C. Flooding also significantly disrupted elemental cycling (nitrogen, phosphorus and carbon) as evidenced by an increased release of P, Fe and NH 4 + into the soil and overlying floodwater and large amounts of CH 4 and NH 3 released to the atmosphere (mainly during the flooding). These effects were more pronounced at higher temperatures (e.g. 45–700 kg CH 4 C ha−1 and 1–5 kg NH 3 N ha−1 at 15 and 25 °C, respectively). In addition, after floodwater removal this NH 4 + was rapidly nitrified leading to large losses of N 2 O (1.0–14.2 kg N 2 O N ha−1 at 5–25 °C, respectively). Especially at higher temperatures, flooding resulted in a reduction in soil microbial biomass (more than 58% of the equivalent unflooded treatment at 25 °C) and changes in microbial community structure (assessed by PLFAs). Further, some of these changes persisted after flood removal including a loss of actinomycetes, arbuscular mycorrhizal fungi and fungi. Overall, we conclude that ecosystem responses to extreme weather events are critically dependent on temperature with those occurring at higher temperatures having a greater negative impact than those at the lowest temperature (5 °C). The large potential release of CH 4 and N 2 O also suggests that flood events should be considered as a potential source of GHGs when comparing top-down and bottom-up calculations of national inventories, and that further work is needed to better refine GHG emission estimates for these events. Highlights • Flooding induced a rapid release of nutrients, especially at higher temperatures. • 700 kg CH 4 C ha−1 and 5 kg NH 3 N ha−1 were released in the flood phase at 25 °C. • During soil recovery, nitrification led to 1.0–14.2 kg N 2 O N ha−1 losses at 5–25 °C. • Flooding reduced soil microbial biomass, actinomycetes and arbuscular mycorrhiza. • Flooding reduced biomass production by 18% at 5 °C, 50% at 15 °C and 95% at 25 °C. [ABSTRACT FROM AUTHOR]

The research advance in cyclic hydroxamic acids was reviewed in this paper. Cyclic hydroxamic acids are the important natural products of cereal crops. They and their respective derivatives are the constitutive compounds of a wide variety of gramineous plants and few dicot plants. They have structural diversity and different natural occurrences. Because of their phytotoxic properties, cyclic hydroxamic acids show a great variety of biological activities. They are the defensive agents against plant diseases, pests, nematodes and other plants. The distribution of cyclic hydroxamic acids in Zea mays and their variation in relation to the age were focused on in the paper. In Zea mays, there are structural diversity of cyclic hydroxamic acids and related benzoxazolinones. DIMBOA (1,4-benzoxazin-3(4H)-ones) is the most abundant derivative in Zea mays. The content of cyclic hydroxamic acids is strongly cultivar-dependent in Zea mays. Hydroxamic acids are not present in seeds. After germination, the level of DIMBOA increases, and the maximum level occurs in young seedlings a few days after germination. DIMBOA exists in all parts of plants, and its concentration is generally higher in shoots than in roots. In all stages, the young leaves of Zea mays have relatively high content of DIMBOA. The concentrations of these hydroxamic acids are highly dependent on environmental growth conditions. Under UV-light and water deficiencies, the levels of hydroxamic acids in plant increase rapidly. Cyclic hydroxamic acids exuded by Zea mays root can be quantitatively analyzed by HPLC. Supplying iron can significantly increase the exudation of DIMBOA from Zea mays root.

The chemical components of the volatiles from Vetiveria zizanioides were analyzed by SPME and GC-MS. In the roots, the main component was valencene (30.36%), while in the shoots and leaves, they were 9-octadecenamide (33.50%), 2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene (27.46%), and 1,2-benzendicarboxylic acid, diisooctyl ester(18.29%). The results showed that there were many terpenoids in the volatils. In shoot volatiles, there existed 3 monoterpenes, 2 sequiterpenes and 1 triterpene. Most of the volatiles in roots were sesquiterpenes.

The effect of transgenic plants on the biodiversity of agroecosystem is an important environmental issue. There are many researches in this field at home and abroad recently. This paper reviewed the advances of the researches based on three levels of biodiversity as genetic diversity, species diversity and ecosystem diversity. They included following aspects: the effect of insect-resistant transgenic crops on target pest; the effect of herbicide-resistant transgenic crops on crops and wild weedy relatives; the effect of virus-resistant transgenic crops on virus; and the effect of transgenic crops on non-target organisms. This paper also discussed the effect of transgenic crops on soil ecosystem and crop genetic diversity. Their potential risks included uncontrolled flows of genes to wild relatives; development of herbicide, insect, and virus resistance in wild relatives; reduced crop genetic diversity; and adverse effects on organisms that were not pests, such as beneficial insects.