Differences in flooding tolerance between species from two wetland habitats with contrasting hydrology: implications for vegetation development in future floodwater retention areas

Genome-wide identification and characterization of ADH gene family and the expression under different abiotic stresses in tomato (Solanum lycopersicum L.)

The SlADH gene plays a key role in environmental stress response. However, limited studies exist regarding the tomato SlADH gene. In this study, we identified 35 SlADH genes in tomato by genome-wide identification. Among the 12 chromosomes of tomato, SlADH gene is distributed on 10 chromosomes, among which the 7th and 10th chromosomes have no family members, while the 11th chromosome has the most members with 8 family members. Members of this gene family are characterized by long coding sequences, few amino acids, and introns that make up a large proportion of the genetic structure of most members of this family. Moreover, the molecular weight of the proteins of the family members was similar, and the basic proteins were mostly, and the overall distribution was relatively close to neutral (pI = 7). This may indicate that proteins in this family have a more conserved function. In addition, a total of four classes of cis-acting elements were detected in all 35 SlADH promoter regions, most of which were associated with biotic and abiotic stresses. The results indicate that SlADH gene had a certain response to cold stress, salt stress, ABA treatment and PEG stress. This study provides a new candidate gene for improving tomato stress resistance.

Identification of time-varying wetlands neglected in Pakistan through remote sensing techniques

Aside from Ramsar Convention awareness programs, the concept of wetlands is mostly ignored in developing countries. Wetland ecosystems are essential to hydrological cycles, ecosystem diversity, climatic change, and economic activity. Under the Ramsar Convention, there are 2414 wetlands that are internationally recognized, and Pakistan is home to 19 of them. The major goal of this study is to use the satellite image technology to locate Pakistan's underutilized wetlands (Borith, Phander, Upper Kachura, Satpara, and Rama Lakes). The other goals are to understand how these wetlands are affected by climate change, ecosystem change, and water quality. We used analytical techniques including supervised classification and Tasseled Cap Wetness to identify the wetlands. To find changes caused by climate change, Quick Bird high-resolution images was used to create the change detection index. Tasseled Cap Greenness and the Normalized Difference Turbidity Index were also used to assess the water quality and changes in the ecology in these wetlands. Sentinel-2 was used to analyze data from 2010 and 2020. ASTER DEM was also used to do a watershed analysis. The land surface temperature (°C) of a few selected wetlands was calculated using Modis data. Rainfall (mm) data was taken from PERSIANN (precipitation estimation from remotely sensed information using artificial neural networks) databases. Results indicated that in 2010, the water content of Borith, Phander, Upper Kachura, Satpara, and Rama Lakes was 22.83%, 20.82%, 22.26%, 24.40%, and 22.91%. While in 2020, these lakes' water ratios are 21.33%, 20.65%, 21.76%, 23.85%, and 22.59%, respectively. Therefore, the competent authorities must take precautions to ensure that these wetlands are preserved in the future in order to improve the dynamics of the ecosystem.

The effects of water control on the survival and growth of Alternanthera philoxeroides in the vegetative reproduction and seedling stages

Alternanthera philoxeroides (Martius) is an infamous invasive alien plant that is widely distributed in aquatic and terrestrial habitats. To investigate the vegetative reproduction, growth, survival strategy, and the function of leaves in fragment of A. philoxeroides under different water conditions, two water control experiments were conducted with different leaf treatments: (1) water control with stolon fragments, and (2) water control with plants. The water control was subjected to five levels: I 30% soil water content, II 70% soil water content, III 97% soil water content, IV water depth of 5 cm, and V water depth of 10 cm in combination with the two leaf treatments, fragments with two leaves and fragments without leaves. Based on the results, A. philoxeroides produced a significantly higher stem length, node number, leaf number, stem biomass, leaf biomass, and total biomass in the 97% soil water content and in treatments with leaves. Additionally, the stem mass ratio increased and the root mass ratio decreased with the increase of the water content. In Exp. 1, the survival rate was the highest in the 97% water content and was 0 in the 30% water content. Therefore, the leaves of stolon fragments contribute to the vegetative reproduction and growth of A. philoxeroides. In response to different water conditions, A. philoxeroides adopts different strategies according to the resource reserves by itself, which are conducive to its survival and widespread occurrence.

Wetland Surface Water Detection from Multipath SAR Images Using Gaussian Process-Based Temporal Interpolation

Wetlands provide society with a myriad of ecosystem services, such as water storage, food sources, and flood control. The ecosystem services provided by a wetland are largely dependent on its hydrological dynamics. Constant monitoring of the spatial extent of water surfaces and the duration of flooding of a wetland is necessary to understand the impact of drought on the ecosystem services a wetland provides. Synthetic aperture radar (SAR) has the potential to reveal wetland dynamics. Multitemporal SAR image analysis for wetland monitoring has been extensively studied based on the advances of modern SAR missions. Unfortunately, most previous studies utilized monopath SAR images, which result in limited success. Tracking changes in individual wetlands remains a challenging task because several environmental factors, such as wind-roughened water, degrade image quality. In general, the data acquisition frequency is an important factor in time series analysis. We propose a Gaussian process-based temporal interpolation (GPTI) method that enables the synergistic use of SAR images taken from multiple paths. The proposed model is applied to a series of Sentinel-1 images capturing wetlands in Okanogan County, Washington State. Our experimental analysis demonstrates that the multiple path analysis based on the proposed method can extract seasonal changes more accurately than a single path analysis.

Alternative transient states and slow plant community responses after changed flooding regimes

Climate change will have large consequences for flooding frequencies in freshwater systems. In interaction with anthropogenic activities (flow regulation, channel restoration and catchment land-use) this will both increase flooding and drought across the world. Like in many other ecosystems facing changed environmental conditions, it remains difficult to predict the rate and trajectory of vegetation responses to changed conditions. Given that critical ecosystem services (e.g. bank stabilization, carbon subsidies to aquatic communities or water purification) depend on riparian vegetation composition, it is important to understand how and how fast riparian vegetation responds to changing flooding regimes. We studied vegetation changes over 19 growing seasons in turfs that were transplanted in a full-factorial design between three riparian elevations with different flooding frequencies. We found that (a) some transplanted communities may have developed into an alternative stable state and were still different from the target community, and (b) pathways of vegetation change were highly directional but alternative trajectories did occur, (c) changes were rather linear but faster when flooding frequencies increased than when they decreased, and (d) we observed fastest changes in turfs when proxies for mortality and colonization were highest. These results provide rare examples of alternative transient trajectories and stable states under field conditions, which is an important step towards understanding their drivers and their frequency in a changing world.

Plant uptake and availability of antimony, lead, copper and zinc in oxic and reduced shooting range soil

Shooting ranges polluted by antimony (Sb), lead (Pb), copper (Cu) and zinc (Zn) are used for animal grazing, thus pose a risk of contaminants entering the food chain. Many of these sites are subject to waterlogging of poorly drained soils. Using field lysimeter experiments, we compared Sb, Pb, Cu and Zn uptake by four common pasture plant species (Lolium perenne, Trifolium repens, Plantago lanceolata and Rumex obtusifolius) growing on a calcareous shooting range soil under waterlogged and drained conditions. To monitor seasonal trends, the same plants were collected at three times over the growing season. Additionally, variations in soil solution concentrations were monitored at three depths over the experiment. Under reducing conditions, soluble Sb concentrations dropped from ∼50 μg L^-1 to ∼10 μg L^-1, which was attributed to the reduction of Sb(V) to Sb(III) and the higher retention of the trivalent species by the soil matrix. Shoot Sb concentrations differed by a factor of 60 between plant species, but remained at levels <0.3 μg g^-1. Despite the difference in soil solution concentrations between treatments, total Sb accumulation in shoots for plants collected on the waterlogged soil did not change, suggesting that Sb(III) was much more available for plant uptake than Sb(V), as only 10% of the total Sb was present as Sb(III). In contrast to Sb, Pb, Cu and Zn soil solution concentrations remained unaffected by waterlogging, and shoot concentrations were significantly higher in the drained treatment for many plant species. Although showing an increasing trend over the season, shoot metal concentrations generally remained below regulatory values for fodder plants (40 μg g^-1 Pb, 150 μg g^-1 Zn, 15-35 μg g^-1 Cu), indicating a low risk of contaminant transfer into the food chain under both oxic and anoxic conditions for the type of shooting range soil investigated in this study.

Structural and functional responses of plant communities to climate change-mediated alterations in the hydrology of riparian areas in temperate Europe

The hydrology of riparian areas changes rapidly these years because of climate change‐mediated alterations in precipitation patterns. In this study, we used a large‐scale in situ experimental approach to explore effects of drought and flooding on plant taxonomic diversity and functional trait composition in riparian areas in temperate Europe. We found significant effects of flooding and drought in all study areas, the effects being most pronounced under flooded conditions. In near‐stream areas, taxonomic diversity initially declined in response to both drought and flooding (although not significantly so in all years) and remained stable under drought conditions, whereas the decline continued under flooded conditions. For most traits, we found clear indications that the functional diversity also declined under flooded conditions, particularly in near‐stream areas, indicating that fewer strategies succeeded under flooded conditions. Consistent changes in community mean trait values were also identified, but fewer than expected. This can have several, not mutually exclusive, explanations. First, different adaptive strategies may coexist in a community. Second, intraspecific variability was not considered for any of the traits. For example, many species can elongate shoots and petioles that enable them to survive shallow, prolonged flooding but such abilities will not be captured when applying mean trait values. Third, we only followed the communities for 3 years. Flooding excludes species intolerant of the altered hydrology, whereas the establishment of new species relies on time‐dependent processes, for instance the dispersal and establishment of species within the areas. We expect that altered precipitation patterns will have profound consequences for riparian vegetation in temperate Europe. Riparian areas will experience loss of taxonomic and functional diversity and, over time, possibly also alterations in community trait responses that may have cascading effects on ecosystem functioning.

Genotypic variation in growth and metabolic responses of perennial ryegrass exposed to short-term waterlogging and submergence stress

Physiological mechanisms of waterlogging (WL) and submergence (SM) tolerance are not well understood in perennial grasses used for turf and forage. The objective of this study was to characterize growth, antioxidant activity and lipid peroxidation of perennial ryegrass (Lolium perenne) exposed to short-term WL and SM. 'Silver Dollar' (turf-type cultivar), 'PI418714' (wild accession), 'Kangaroo Valley' (forage-type cultivar) and 'PI231569' (unknown status) varying in growth habits and leaf texture were subjected to 7 d of WL and SM in a growth chamber. Plant height was unaffected by WL but was significantly reduced by SM for all grasses except PI418714. The SM treatment caused greater reductions in leaf chlorophyll and total carotenoid concentrations. Substantial declines in water-soluble carbohydrate concentrations were found in the shoots and roots under SM, particularly in Kangaroo Valley and PI231569, two relatively fast-growing genotypes. Significant increases in malondialdehyde concentrations were noted in the shoots and roots of all genotypes exposed to WL and SM, but to a greater extent in Kangaroo Valley and PI231569 under SM. Shoot activities of catalase (CAT) and peroxidase (POD) increased under SM, more pronounced in Silver Dollar and PI418714, two relatively slow-growing genotypes. Waterlogging or SM stresses decreased root activities of superoxide dismutase, CAT, POD and ascorbate peroxidase, especially for Kangaroo Valley and PI231569. The results indicated that maintenance of antioxidant activity and carbohydrate and minimization of lipid peroxidation could contribute to better waterlogging or submergence tolerance of perennial ryegrasses.

Riparian plant community responses to increased flooding: a meta-analysis

A future higher risk of severe flooding of streams and rivers has been projected to change riparian plant community composition and species richness, but the extent and direction of the expected change remain uncertain. We conducted a meta-analysis to synthesize globally available experimental evidence and assess the effects of increased flooding on (1) riparian adult plant and seedling survival, (2) riparian plant biomass and (3) riparian plant species composition and richness. We evaluated which plant traits are of key importance for the response of riparian plant species to flooding. We identified and analysed 53 papers from ISI Web of Knowledge which presented quantitative experimental results on flooding treatments and corresponding control situations. Our meta-analysis demonstrated how longer duration of flooding, greater depth of flooding and, particularly, their combination reduce seedling survival of most riparian species. Plant height above water level, ability to elongate shoots and plasticity in root porosity were decisive for adult plant survival and growth during longer periods of flooding. Both 'quiescence' and 'escape' proved to be successful strategies promoting riparian plant survival, which was reflected in the wide variation in survival (full range between 0 and 100%) under fully submerged conditions, while plants that protrude above the water level (>20 cm) almost all survive. Our survey confirmed that the projected increase in the duration and depth of flooding periods is sufficient to result in species shifts. These shifts may lead to increased or decreased riparian species richness depending on the nutrient, climatic and hydrological status of the catchment. Species richness was generally reduced at flooded sites in nutrient-rich catchments and sites that previously experienced relatively stable hydrographs (e.g. rain-fed lowland streams). Species richness usually increased at sites in desert and semi-arid climate regions (e.g. intermittent streams).

Diversity and above-ground biomass patterns of vascular flora induced by flooding in the drawdown area of China's Three Gorges Reservoir

Hydrological alternation can dramatically influence riparian environments and shape riparian vegetation zonation. However, it was difficult to predict the status in the drawdown area of the Three Gorges Reservoir (TGR), because the hydrological regime created by the dam involves both short periods of summer flooding and long-term winter impoundment for half a year. In order to examine the effects of hydrological alternation on plant diversity and biomass in the drawdown area of TGR, twelve sites distributed along the length of the drawdown area of TGR were chosen to explore the lateral pattern of plant diversity and above-ground biomass at the ends of growing seasons in 2009 and 2010. We recorded 175 vascular plant species in 2009 and 127 in 2010, indicating that a significant loss of vascular flora in the drawdown area of TGR resulted from the new hydrological regimes. Cynodon dactylon and Cyperus rotundus had high tolerance to short periods of summer flooding and long-term winter flooding. Almost half of the remnant species were annuals. Species richness, Shannon-Wiener Index and above-ground biomass of vegetation exhibited an increasing pattern along the elevation gradient, being greater at higher elevations subjected to lower submergence stress. Plant diversity, above-ground biomass and species distribution were significantly influenced by the duration of submergence relative to elevation in both summer and previous winter. Several million tonnes of vegetation would be accumulated on the drawdown area of TGR in every summer and some adverse environmental problems may be introduced when it was submerged in winter. We conclude that vascular flora biodiversity in the drawdown area of TGR has dramatically declined after the impoundment to full capacity. The new hydrological condition, characterized by long-term winter flooding and short periods of summer flooding, determined vegetation biodiversity and above-ground biomass patterns along the elevation gradient in the drawdown area.

Flooding and fragment size interact to determine survival and regrowth after fragmentation in two stoloniferous Trifolium species

Clonal plants, which reproduce by means of stolons and rhizomes, are common in frequently flooded habitats. Resilience to disturbance is an important trait enabling plants to survive in such highly disturbed habitats. Resource storage is thought to enable clonal plants to resume growth after clonal fragmentation caused by disturbance. Here we investigated if submergence prior to disturbance reduces survival and regrowth of clonal fragments and whether or not genotypes originating from highly disturbed riverine habitats are more resistant to mechanical disturbance than genotypes from less disturbed coastal dune slack habitats. We further tested if variation in survival and regrowth was affected by internode size. Clones from contrasting habitats of two closely related Trifolium species were first genotypically characterized by amplification fragment length polymorphism and then subjected to soil flooding and subsequent clonal fragmentation. These species differ with respect to their abundance in riverine and dune slack habitats, with Trifolium repens mainly occurring in riverine grasslands and Trifolium fragiferum in coastal dune slacks. Soil flooding decreased survival and regrowth by up to 80 %. Plants originating from riverine grasslands were less negatively affected by fragmentation than plants from dune slack habitats. Surprisingly, ramets did not always benefit from being attached to a larger internode, as internode size was often negatively correlated with survival after fragmentation. Regrowth, on the other hand, was generally positively correlated with internode size. These unexpected results indicate that there may be contrasting selection pressures on internode size in stoloniferous species growing in severely disturbed habitats.

The negative effects of cadmium on Bermuda grass growth might be offset by submergence

Revegetation in the water-level-fluctuation zone (WLFZ) could stabilize riverbanks, maintain local biodiversity, and improve reservoir water quality in the Three Gorges Reservoir Region (TGRR). However, submergence and cadmium (Cd) may seriously affect the survival of transplantations. Bermuda grass (Cynodon dactylon) is a stoloniferous and rhizomatous prostrate weed displaying high growth rate. A previous study has demonstrated that Bermuda grass can tolerate deep submergence and Cd stress, respectively. In the present study, we further analyzed physiological responses of Bermuda grass induced by Cd-and-submergence stress. The ultimate goal was to explore the possibility of using Bermuda grass for revegetation in the WLFZ of China's TGRR and other riparian areas. The Cd-and-submergence-treated plants had higher malondialdehyde contents and peroxidase than control, and both increased with the Cd concentration increase. All treated plants catalase activity increased with the experimental duration increases, and their superoxide dismutase also gradually increased with the Cd concentration from 1 day to 15 days. Total biomass of the same Cd-and-submergence plants increased along the experimental duration as well. Plants exposed to Cd-and-submergence stress showed shoot elongation. The heights of all treated plants were taller than those of the control. Leaf chlorophyll contents, maximum leaf length, and soluble sugars contents of all the Cd-and-submergence-treated plants were more than those of the untreated control. Although Cd inhibits plants growth, decreases chlorophyll and biomass content, and with the submergence induced the leaf and shoot elongation, more part of the Cd-and-submergence stress plants appeared in the air, exhibited fast growth with maintenance of leaf color, which guaranteed the plants' photosynthesis, and ensured the total biomass and carbohydrate sustainability, further promoting Cd-and-submergence tolerance. The results imply that the negative effects of cadmium on Bermuda grass growth might be offset by submergence.

Flooding tolerance: O2 sensing and survival strategies

The investigation of flooding survival strategies in model, crop and wild plant species has yielded insights into molecular, physiological and developmental mechanisms of soil flooding (waterlogging) and submergence survival. The antithetical flooding escape and quiescence strategies of deepwater and submergence tolerant rice (Oryza sativa), respectively, are regulated by members of a clade of ethylene responsive factor transcriptional activators. This knowledge paved the way for the discovery that these proteins are targets of a highly conserved O2-sensing protein turnover mechanism in Arabidopsis thaliana. Further examples of genes that regulate transcription, root and shoot metabolism or development during floods have emerged. With the rapid advancement of genomic technologies, the mining of natural genetic variation in flooding tolerant wild species may ultimately benefit crop production.

Plant communities in relation to flooding and soil characteristics in the water level fluctuation zone of the Three Gorges Reservoir, China

With the filling of the Three Gorges Reservoir, original vegetation in the water level fluctuation zone (WLFZ) between the elevations of 145 and 175 m disappeared due to the reversal of submergence time (winter flooding) and prolonged inundation duration (nearly half a year). To better understand the relationships between the environmental factors and recovered plant communities for reconstructing floristically diverse riparian zone, we conducted a field survey in 11 sites in the WLFZ in June 2010, and vegetation composition, flooding characteristics, heavy metals, and soil major nutrients were determined. Consequently, the canonical correspondence analysis was used to investigate the relationships between plant species composition and flooding characteristics, heavy metal contamination, and soil nutrients. Results demonstrated that vegetation in the WLFZ was dominated by annuals, i.e., Echinochloa crusgalli and Bidens tripartita, and perennials including Cynodon dactylon, and plant species richness and diversity were negatively associated with flooding duration, heavy metal contamination, and nutrients including total phosphorus, available phosphorus, available potassium, and nitrate. Our results suggest that plant species, recovering mainly through soil seed bank and regeneration of remnant individuals, have been influenced by the combined effects of environmental factors.

Regression analysis of growth responses to water depth in three wetland plant species

BACKGROUND AND AIMS

Plant species composition in wetlands and on lakeshores often shows dramatic zonation, which is frequently ascribed to differences in flooding tolerance. This study compared the growth responses to water depth of three species (Phormium tenax, Carex secta and Typha orientalis) differing in depth preferences in wetlands, using non-linear and quantile regression analyses to establish how flooding tolerance can explain field zonation.

METHODOLOGY

Plants were established for 8 months in outdoor cultures in waterlogged soil without standing water, and then randomly allocated to water depths from 0 to 0.5 m. Morphological and growth responses to depth were followed for 54 days before harvest, and then analysed by repeated-measures analysis of covariance, and non-linear and quantile regression analysis (QRA), to compare flooding tolerances.

PRINCIPAL RESULTS

Growth responses to depth differed between the three species, and were non-linear. Phormium tenax growth decreased rapidly in standing water >0.25 m depth, C. secta growth increased initially with depth but then decreased at depths >0.30 m, accompanied by increased shoot height and decreased shoot density, and T. orientalis was unaffected by the 0- to 0.50-m depth range. In P. tenax the decrease in growth was associated with a decrease in the number of leaves produced per ramet and in C. secta the effect of water depth was greatest for the tallest shoots. Allocation patterns were unaffected by depth.

CONCLUSIONS

The responses are consistent with the principle that zonation in the field is primarily structured by competition in shallow water and by physiological flooding tolerance in deep water. Regression analyses, especially QRA, proved to be powerful tools in distinguishing genuine phenotypic responses to water depth from non-phenotypic variation due to size and developmental differences.

Differential growth response and carbohydrate metabolism of global collection of perennial ryegrass accessions to submergence and recovery following de-submergence

Submergence can severely affect the growth of perennial grasses. The variations in growth and the physiological responses of perennial grass germplasm to submergence stress are not well understood. The objective of this study was to characterize the responses of diverse perennial ryegrass accessions to submergence and their recovery following de-submergence. One hundred globally collected perennial ryegrass accessions were submerged for 7d followed by 7d of recovery in two experiments (Exp 1 and Exp 2), respectively. Compared to the pattern of the controls, the overall distribution in leaf color, chlorophyll fluorescence, plant height (HT), and growth rate (GR) shifted toward a high frequency of lower values under submergence in both experiments. The accessions were generally grouped into three types: fast growth with maintenance of color (escape, T1), slow growth with maintenance of color (quiescence, T2), and slow growth with loss of color (susceptible, ST). Under submergence, T1 had higher HT and GR than the other two groups except for GR of T2 in Exp 2 and had higher water-soluble carbohydrate (WSC) and fructan concentrations, as well as fructan to WSC ratio, than ST in Exp 1. Recovery of HT and GR were generally close to that of the control level except for HT of ST in Exp 2, but the carbohydrates fully recovered in all types of plants after 7d of de-submergence. Differential responses of perennial ryegrass accessions to submergence are useful in creating more tolerant materials and in further characterizing physiological and molecular mechanisms of submergence tolerance.

Association of simple sequence repeat (SSR) markers with submergence tolerance in diverse populations of perennial ryegrass

Submergence stress can cause the death of grass plants. Identification of the association between molecular markers and submergence tolerance-related traits facilitates an efficient selection of the tolerant cultivars for commercial production. A global collection of 99 diverse perennial ryegrass (Lolium perenne L.) accessions was evaluated for submergence tolerance and analyzed with 109 simple sequence repeat (SSR) markers. Submergence significantly reduced leaf color, chlorophyll fluorescence (F(v)/F(m)), maximum plant height (HT), and relative growth rate (RGR). Significant variations in these trait values were observed among the accessions under submerged conditions. Rapid linkage-disequilibrium (LD) decay was identified within 4cM. The analysis of population structure (Q) identified four subpopulations in the collection, but no obvious relative kinship (K) was found. The Q model was the best to describe associations between SSR and traits, compared to the simple linear, K, and Q + K models. Fifteen SSR markers were associated with a reduction in leaf color, F(v)/F(m), HT, and RGR under submergence stress using the Q model. These markers can be used for genetic improvement of submergence tolerance of perennial ryegrass after further validation. The diverse populations of perennial ryegrass is a valuable resource for association mapping of stress tolerance-related physiological traits.

Plant communities in relation to flooding and soil contamination in a lowland Rhine River floodplain

Using canonical correspondence analysis (CCA), relationships were investigated between plant species composition and flooding characteristics, heavy metal contamination and soil properties in a lowland floodplain of the Rhine River. Floodplain elevation and yearly average flooding duration turned out to be more important for explaining variation in plant species composition than soil heavy metal contamination. Nevertheless, plant species richness and diversity showed a significant decrease with the level of contamination. As single heavy metal concentrations seemed mostly too low for causing phytotoxic effects in plants, this trend is possibly explained by additive effects of multiple contaminants or by the concomitant influences of contamination and non-chemical stressors like flooding. These results suggest that impacts of soil contamination on plants in floodplains could be larger than expected from mere soil concentrations. In general, these findings emphasize the relevance of analyzing effects of toxic substances in concert with the effects of other relevant stressors.

Evolution and mechanisms of plant tolerance to flooding stress

BACKGROUND

In recognition of the 200th anniversary of Charles Darwin's birth, this short article on flooding stress acknowledges not only Darwin's great contribution to the concept of evolution but also to the study of plant physiology. In modern biology, Darwin-inspired reductionist physiology continues to shed light on mechanisms that confer competitive advantage in many varied and challenging environments, including those where flooding is prevalent.

SCOPE

Mild flooding is experienced by most land plants but as its severity increases, fewer species are able to grow and survive. At the extreme, a highly exclusive aquatic lifestyle appears to have evolved numerous times over the past 120 million years. Although only 1-2% of angiosperms are aquatics, some of their adaptive characteristics are also seen in those adopting an amphibious lifestyle where flooding is less frequent. Lowland rice, the staple cereal for much of tropical Asia falls into this category. But, even amongst dry-land dwellers, or certain of their sub-populations, modest tolerance to occasional flooding is to be found, for example in wheat. The collection of papers summarized in this article describes advances to the understanding of mechanisms that explain flooding tolerance in aquatic, amphibious and dry-land plants. Work to develop more tolerant crops or manage flood-prone environments more effectively is also included. The experimental approaches range from molecular analyses, through biochemistry and metabolomics to whole-plant physiology, plant breeding and ecology.