Nitrogen availability affects the responses of marsh grass and sedge plants (Phragmites australis and Bolboschoenus planiculmis) to flooding time

Flooding time and external nitrogen (N) input have been projected to be the main threats to marsh ecosystems in the scenario of more intense flooding events and N deposition. How flooding and N addition experienced at different growth stages interact in determining phenotypic change remains scarce. We established a controlled experiment (3 flooding time treatments x 5 N addition levels) using two herbaceous marsh species (Phragmites australis and Bolboschoenus planiculmis) to assess the responses of six key traits to environmental changes and the indication of plant performance. Early flooding reduced plant height and aboveground biomass of P. australis and below/aboveground biomass ratio of B. planiculmis and increased below/aboveground biomass ratio of P. australis and root biomass of B. planiculmis, whereas late flooding reduced root biomass of P. australis and ramet number and aboveground biomass of B. planiculmis. The combination of flooding and high N (16 and 32 g N m-2) exerted negative effects on ramet number of both plant species. The interaction of early flooding and low-medium N (8 and 16 g N m-2) inhibited clonal/belowground biomass ratio of both plant species. The combination of early flooding and low N (0, 4 and 8 g N m-2) promoted root biomass and below/aboveground biomass ratio of P. australis. Ramet number, plant height, and root biomass explained 80-90 % of aboveground biomass variation of both plant species, and the contribution of ramet number was greater than that of the other two traits. These results highlight that the influence of flooding time and external N input on the performance of marsh plants depends on species identity. Meanwhile, the ramet number-plant height-root biomass (RHR) strategy is supposed to be the adaptation strategy of wetland clonal plants to environmental changes, and clonal reproductive traits should be incorporated into vegetation dynamics models for marsh plants.

ADSP: An adaptive sample pooling strategy for diagnostic testing

BACKGROUND

We often must conduct diagnostic tests on a massive volume of samples within a limited time during outbreaks of infectious diseases (e.g., COVID-19,screening) or repeat many times routinely (e.g., regular and massive screening for plant virus infections in farms). These tests aim to obtain the diagnostic result of all samples within a limited time. In such scenarios, the limitation of testing resources and human labor drives the need to pool individual samples and test them together to improve testing efficiency. When a pool is positive, further testing is required to identify the affected individuals; whereas when a pool is negative, we conclude all individuals in the pool are negative. How one splits the samples into pools is a critical factor affecting testing efficiency.

OBJECTIVE

We aim to find the optimal strategy that adaptively guides users on optimally splitting the sample cohort into test-pools.

METHODS

We developed an algorithm that minimizes the expected number of tests needed to obtain the diagnostic results of all samples. Our algorithm dynamically updates the critical information according to the result of the most recent test and calculates the optimal pool size for the next test. We implemented our novel adaptive sample pooling strategy into a web-based application, ADSP (https://ADSP.uvic.ca). ADSP interactively guides users on how many samples to be pooled for the current test, asks users to report the test result back and uses it to update the best strategy on how many samples to be pooled for the next test.

RESULTS

We compared ADSP with other popular pooling methods in simulation studies, and found that ADSP requires fewer tests to diagnose a cohort and is more robust to the inaccurate initial estimate of the test cohort's disease prevalence.

CONCLUSION

Our web-based application can help researchers decide how to pool their samples for grouped diagnostic tests. It improves test efficiency when grouped tests are conducted.

Leaf transcriptome analysis of Medicago ruthenica revealed its response and adaptive strategy to drought and drought recovery

BACKGROUND

Drought is one of the main causes of losses in forage crop yield and animal production. Medicago ruthenica (L.) cv. Zhilixing is a high-yielding alfalfa cultivar also known for its high tolerance to drought. We analyzed the transcriptome profile of this cultivar throughout drought stress and recovery and we were able to describe its phased response through the expression profiles of overlapping gene networks and drought-specific genes.

RESULTS

The ABA and auxin signal transduction pathways are overlapping pathways in response to drought and drought recovery in forage crops. Medicago ruthenica (L.) cv. Zhilixing adopts different strategies at different degrees of drought stress. On the 9th day of drought, transcriptional regulations related to osmoregulation are enhanced mainly through increased activities of carbohydrate and amino acid metabolism, while photosynthetic activities were reduced to slow down growth. With drought prolonging, on the 12th day of drought, the synthesis of proline and other stored organic substances was suppressed in general. After recovery, Medicago ruthenica synthesizes flavonoids through the flavonoid biosynthesis pathway to remove accumulated ROS and repair the oxidative damage from water stress. In addition, the regulation of circadian rhythm seems to accelerate the drought recovery process.

CONCLUSIONS

Medicago ruthenica adapts to drought by regulating the osmoregulatory system and photosynthesis, which appears to involve the ABA and auxin signaling pathways as key regulators. Furthermore, the synthesis of flavonoids and the regulation of the circadian rhythm can accelerate the recovery process. These results enriched our knowledge of molecular responses to drought and drought recovery in Medicago ruthenica and provide useful information for the development of new legume forage grass varieties with improved adaptability to drought stress.

The adaptive strategies of yaks to live in the Asian highlands

The yak (Bos grunniens), an indigenous herbivore raised at altitudes between 3,000 and 5,000 m above sea level, is closely linked to more than 40 ethnic communities and plays a vital role in the ecological stability, livelihood security, socio-economic development, and ethnic cultural traditions in the Asian highlands. They provide the highlanders with meat, milk, fibres, leather and dung (fuel). They are also used as pack animals to transport goods, for travel and ploughing, and are important in many religious and traditional ceremonies. The Asian highlands are known for an extremely, harsh environment, namely low air temperature and oxygen content and high ultraviolet light and winds. Pasture availability fluctuates greatly, with sparse pasture of poor quality over the long seven-month cold winter. After long-term natural and artificial selections, yaks have adapted excellently to the harsh conditions: 1) by genomics, with positively selected genes involved in hypoxia response and energy metabolism; 2) anatomically, including a short tongue with a weak sense of taste, and large lung and heart; 3) physiologically, by insensitivity to hypoxic pulmonary vasoconstriction, maintaining foetal haemoglobin throughout life, and low heart rate and heat production in the cold season; 4) behaviourlly, by efficient grazing and selecting forbs with high nutritional contents; 5) by low nitrogen and energy requirements for maintenance and low methane emission and nitrogen excretion, namely, ‘Low-Carbon’ and ‘Nitrogen-Saving’ traits; 6) by harboring unique rumen microbiota with a distinct maturation pattern, that has co-evolved with host metabolism. This review aims to provide an overview of the comprehensive adaptive strategies of the yak to the severe conditions of the highlands. A better understanding of these strategies that yaks employ to adapt to the harsh environment could be used in improving their production, breeding and management, and gaining benefits in ecosystem service and a more resilient livelihood to climate change in the Asian highlands.

Effect of microfibers combined with UV-B and drought on plant community

There is an increasing recognition that microplastics contamination in soils has become an important threat for terrestrial ecosystems, and can interact with drought. In addition, due to the increasingly serious environmental pollution and the destruction of the ozone layer, the UV-B radiation to the earth's surface has gradually increased. However, we currently have no information about potential effects of microplastics, UV-B, and drought on plant communities. In order to make up for the vacancy, we conducted an experiment with grassland plant communities. Polyester fiber microplastics (absent, present), UV-B (fully transparent polythene film, attenuating UV-B radiation), and soil water conditions (well-watered, drought) were applied in a fully factorial design. A plant community consisting of four indigenous species and one invasive species, co-occurring in the terrestrial ecosystem of the northern temperate zone was established, and we investigated the effects of microplastics, UV-B, drought and their interactions on plant functional traits and plant community structure. We found that shoot and root biomass decreased with drought but increased with microfibers, and drought significantly decreased specific leaf area at the community level. Physiological and biochemical indexes of individual species and plant community were affected by microfibers, UV-B, drought and their interaction to a varying degree. More importantly, five species were divided into three clusters along PC1 corresponding to individuals from G. longituba and P. depressa, B. bipinnata and M. sativa, plus G. parviflora, which indicated that at the same conditions, G. parviflora would occupy unique ecological niches that affect the growth of native species. Our research offers insights into the mechanisms of the coexistence of native and invasive plants, as well as the ecological consequences of microplastics and other environment factors on plant communities.

Adaptive coping strategies towards seasonal change impacts: Indonesian small-scale fisherman household

Small-scale fishers are always expected to adapt to fishing activities that cannot be conducted all year round due to weather and fishing season. This condition, especially when it is not the fish season, makes fishers face a problem. Notwithstanding, fishermen households need to develop an adequate adaptation strategy to solve the problem of fulfilling their needs, known as coping strategies. This study aims to analyze fishermen households' coping strategies in facing the fishing season and non-fish season by using fishermen's family resources and two types of internal and external family coping strategies. The data were gathered from approximately 150 small-scale fishing households using simple random sampling. The results indicate the fishers do fishing activities in three batch: peak season (68%), mild season (20%), and off-season (12%). The use of resources for fishermen households' coping strategy is carried out by diversifying the sources of household income. Some economic activities include cultivating forest land belonging to the forest department, marine tour guides, livestock, and his wife. This study also confirm that all households use internal family coping strategies with humor indicator as the highest percentage. Accordingly, the households also adopt the external family coping strategy to deal with the existing situation. This strategy follows the local community's characteristics and culture who are friendly and open and based on religion. The household coping strategy strengthening model is generated through the synergy of formal institutional roles in society and government institutions as policymakers.

Genomic reconstruction of fossil and living microorganisms in ancient Siberian permafrost

BACKGROUND

Total DNA (intracellular, iDNA and extracellular, eDNA) from ancient permafrost records the mixed genetic repository of the past and present microbial populations through geological time. Given the exceptional preservation of eDNA under perennial frozen conditions, typical metagenomic sequencing of total DNA precludes the discrimination between fossil and living microorganisms in ancient cryogenic environments. DNA repair protocols were combined with high throughput sequencing (HTS) of separate iDNA and eDNA fraction to reconstruct metagenome-assembled genomes (MAGs) from ancient microbial DNA entrapped in Siberian coastal permafrost.

RESULTS

Despite the severe DNA damage in ancient permafrost, the coupling of DNA repair and HTS resulted in a total of 52 MAGs from sediments across a chronosequence (26-120 kyr). These MAGs were compared with those derived from the same samples but without utilizing DNA repair protocols. The MAGs from the youngest stratum showed minimal DNA damage and thus likely originated from viable, active microbial species. Many MAGs from the older and deeper sediment appear related to past aerobic microbial populations that had died upon freezing. MAGs from anaerobic lineages, including Asgard archaea, however exhibited minimal DNA damage and likely represent extant living microorganisms that have become adapted to the cryogenic and anoxic environments. The integration of aspartic acid racemization modeling and metaproteomics further constrained the metabolic status of the living microbial populations. Collectively, combining DNA repair protocols with HTS unveiled the adaptive strategies of microbes to long-term survivability in ancient permafrost.

CONCLUSIONS

Our results indicated that coupling of DNA repair protocols with simultaneous sequencing of iDNA and eDNA fractions enabled the assembly of MAGs from past and living microorganisms in ancient permafrost. The genomic reconstruction from the past and extant microbial populations expanded our understanding about the microbial successions and biogeochemical alterations from the past paleoenvironment to the present-day frozen state. Furthermore, we provided genomic insights into long-term survival mechanisms of microorganisms under cryogenic conditions through geological time. The combined strategies in this study can be extrapolated to examine other ancient non-permafrost environments and constrain the search for past and extant extraterrestrial life in permafrost and ice deposits on Mars. Video abstract.

Pteridophytes in phytoremediation

Soil contamination by heavy metals and metalloids is a serious problem which needs to be addressed. There are several methods for removal of contaminants, but they are costly, while the method of phytoremediation is eco-friendly and cost-effective. Pteridophytes have been found to remediate heavy metal-contaminated soil. Pteridophytes are non-flowering plant that reproduces by spores. Pteris vittata has been reported as the first fern plant to hyperaccumulate arsenic. The Pteris species belongs to the order Pteridales. Other ferns that are known phytoremediators are, for example, Nephrolepis cordifolia and Hypolepis muelleri (identified as phytostabilisers of Cu, Pb, Zn and Ni); similarly Pteris umbrosa and Pteris cretica accumulate arsenic in leaves. So, pteridophytes have a number of species that accumulate contaminants. Many of them have been identified, while various other are being explored. The present review article describes the phytoremediation potential of pteridophytes plants and suggests as a potential asset for phytoremediation programs.

Robust modified function projective lag synchronization between two nonlinear complex networks with different-dimensional nodes and disturbances

This paper is concerned with a theoretical investigation on the robust modified function projective lag synchronization (MFPLS) between two complex networks with nonlinear couplings, different-dimensional nodes, parameter disturbances and external disturbances. Some novel robust hybrid controllers are designed to address such synchronization problems for networks with and without disturbances, in which adaptive updated laws of disturbances are adopted to attenuate the disturbances occurred in networks. By utilizing Lyapunov functional method, synchronization criteria are derived by strict theoretical proof. Compared with existing jobs, the proposed model and synchronization type are more general. Two examples are presented to verify our results.

Relative impact of meteorological factors and air pollutants on childhood allergic diseases in Shanghai, China

BACKGROUND

Non-optimal weather conditions and air pollution pose a significant threat to children's health. However, the relative impact of different environmental exposures on childhood allergic diseases remains unclear.

OBJECTIVES

This study aimed to quantify the relative impact of meteorological factors and air pollutants on childhood allergic diseases in Shanghai, China.

METHODS

Data on clinical visits due to childhood asthma, allergic rhinitis (AR) and atopic dermatitis (AD) from 2007 to 2017 in Shanghai were collected from Shanghai Children's Medical Center and Xinhua Hospital. The meteorological data (i.e. daily mean temperature, temperature difference, air pressure, air pressure difference, precipitation, relative humidity, sunshine and wind speed) for the same period were obtained from the Shanghai Meteorological Center. Air pollution data (PM₁₀, PM_2.5, NO₂, SO₂ and O₃) were provided by the Shanghai Environmental Protection Agency. Quasi-Poisson regression with distributed lag non-linear models and Poisson regression combined with generalized linear models were used to assess the relative impact of meteorological factors and air pollutants on childhood allergic diseases.

RESULTS

There were a total of 2,410,392 cases of childhood allergic diseases, including 975,771 asthma, 646,975 AR and 787,646 AD. Most of environmental factors were significantly associated with childhood allergic diseases. Daily mean temperature (standard β: -0.076 (95% confidence interval (CI): -0.086, -0.067)) and air pressure (standard β: 0.075 (95% CI: 0.068, 0.082)) seemed to play more important roles than other environmental factors in the occurrence of these allergic diseases. The numbers of these allergic diseases attributable to an interquartile range (IQR) change in meteorological factors also appeared to be greater than those attributable to an IQR change in air pollutants.

CONCLUSIONS

Both climatic variation and air pollution were associated with childhood allergic diseases, but the former appeared to play a more important role in the occurrence of these diseases. These findings may have significant implications for the development of tailored strategies to prevent these rapidly-increasing diseases worldwide.

A general method for estimating seed dormancy and colonisation in annual plants from the observation of existing flora

In plant ecology, characterising colonisation and extinction in plant metapopulations is challenging due to the non-detectable seed bank that allows plants to emerge after several years of absence. In this study, we used a Hidden Markov Model to characterise seed dormancy, colonisation and germination solely from the presence-absence of standing flora. Applying the model to data from a long-term survey of 38 annual weeds across France, we identified three homogeneous functional groups: (1) species persisting preferentially through spatial colonisation, (2) species persisting preferentially through seed dormancy and (3) a mix of both strategies. These groups are consistent with existing ecological knowledge, demonstrating that ecologically meaningful parameters can be estimated from simple presence-absence observations. These results indicate that such studies could contribute to the design of weed management strategies. They also open the possibility of testing life-history theories such as the dormancy/colonisation trade-off in natura.

Differences in below-ground bud bank density and composition along a climatic gradient in the temperate steppe of northern China

BACKGROUND AND AIMS

Understanding the changes in below-ground bud bank density and composition along a climatic gradient is essential for the exploration of species distribution pattern and vegetation composition in response to climatic changes. Nevertheless, investigations on bud banks along climatic gradients are still scarce. The below-ground bud bank is expected to be reduced in size in arid conditions, and costly, bud-bearing organs with long spacers would be replaced by more compact forms with buds that are better protected than those found in moist conditions.

METHODS

How total bud density and composition (different bud bank types) change with aridity (calculated value 0·43-0·91), mean annual precipitation (MAP; 93-420 mm) and mean annual temperature (MAT; -1·51 to 6·93 °C) was tested at 21 sites along a 2500-km climatic gradient in the temperate steppe of northern China.

CONCLUSIONS

Belowground bud bank density decreases towards the dry, hot end of the climatic gradient. Based on the distribution of bud types along the climatic gradient, bulb buds and tiller buds of tussock grasses seem to be more resistant to environmental stress than rhizome buds. The dominance of annual species and smaller bud banks in arid region implies that plant reproductive strategies and vegetation composition will be shifted in scenarios of increased drought under future climate change.

[Comparison of mating calls and adaptive strategies of Amolops wuyiensis and Odorrana tormotus (Anura) in noise-controlled environments]

In order to understand the acoustic characteristics and adaptive strategies of sympatric male Amolops wuyiensis and male Odorrana tormotus in environments controlled for high noise levels, we recorded and analyzed the advertisement calls produced by individual males during breeding season. The results show that A. wuyiensis produced a single type of call composed of variable syllables (from 3 to 6 syllables) with 2~10 pulses over different time periods. The average values of call duration, dominant frequency and signal noise ratio were 2 198.20 ms, 2 231.90 Hz and 33.00 dB respectively. There were no ultrasonic elements in A. wuyiensis calls and they did not have the basis of ultrasonic communication. The average values of call duration, dominant frequency and signal noise ratio of O. tormotus were 331.80 ms, 6 665.50 Hz and 37.00 dB respectively. Call structure of O. tormotus was consistent with previous studies. The noise did not mask the calls from the male A. wuyiensis and male O. tormotus, which have higher frequencies and amplitudes. To fulfill the intra-species communication in a noise-controlled environment, the A. wuyiensis male, which has a low vocal frequency and long transmission length, varied vocal frequency, composition, and duration, the latter of which serves to attract females. By contrast, the male O. tormotus increased vocal frequency, which reduces the energy expended on intra-species communication.