Droughts

Root-knot nematodes (RKN), Meloidogyne spp., have major economic impact on coffee production in Central and South America. Genetic control of RKN constitutes an essential part for integrated pest management strategy. The objective of this study was to evaluate the resistance of Coffea canephora genotypes (clones) to Meloidogyne spp. Sensitive and drought-tolerant coffee genotypes were used to infer their resistance using nematode reproduction factor and histopathology. Eight clonal genotypes were highly resistant to M. paranaensis. 'Clone 14' (drought-tolerant) and 'ESN2010-04' were the only genotypes highly resistant and moderately resistant, respectively, to both M. incognita races 3 and 1. Several clones were highly resistant to both avirulent and virulent M. exigua. Clone 14 and ESN2010-04 showed multiple resistance to major RKNs tested. Roots of 'clone 14' (resistant) and 'clone 22' (susceptible) were histologically studied against infection by M. incognita race 3 and M. paranaensis. Reduction of juvenile (J2) penetration in clone 14 was first seen at 2 to 6 days after inoculation (DAI). Apparent early hypersensitive reaction (HR) was seen in root cortex between 4 and 6 DAI, which led to cell death and prevention of some nematode development. At 12 to 20 DAI, giant cells formed in the vascular cylinder, besides normal development into J3/J4. From 32 to 45 DAI, giant cells were completely degenerated. Late, intense HR and cell death were frequently observed around young females and giant cells reported for the first time in coffee pathosystem. These results provide rational bases for future studies, including prospection, characterization, and expression profiling of genomic loci involved in both drought tolerance and resistance to multiple RKN species.

We investigated forest responses to global warming by observing: (1) planted Pinus halepensis forests, (2) an aridity gradient-with annual precipitation (P) ranging from ~300 to ~700 mm, and (3) periods of wet and dry climate that included the driest period during at least the last 110 years. We examined: (1) how the length of climatic integration periods to which trees are most responsive varies in space and time, (2) the extent to which competition modulates growth decline during drought (2011) and subsequent recovery (2012) years. The temporal scale of rainfall that was most influential on growth shortened in progressing southward, and in the drier than in the wetter period. Long-term underground water storage, as reflected in the relationship of growth to multiple-year rainfall, remained significant up to the point where P ≈ 500 mm. Under drier conditions (P < 500 mm) in both space and time, influential rainfall scales shortened, probably reflecting a diminishing role of wate...

Inositol-(1,4,5)-trisphosphate (InsP3) is a second messenger in plants that increases in response to many stimuli. The metabolic consequences of this signalling pathway are not known. We reduced the basal level of InsP3 in tomato (Solanum lycopersicum cv. Micro-Tom) by expressing the human type I inositol polyphosphate 5-phosphatase (InsP 5-ptase) gene. Transgenic lines producing InsP 5-ptase protein had between 15% and 30% of the basal InsP3 level of control plants. This increased hydrolysis of InsP3 caused dramatic increases in drought tolerance, vegetative biomass and lycopene and hexose concentrations in the fruits. Transcript profiling of root, leaf and fruit tissues identified a small group of genes, including a cell-wall invertase inhibitor gene, that were differentially regulated in all tissues of the InsP 5-ptase expressing plants. Significant differences were found in the amounts of carbohydrates and organic phosphate in these plants. Plants with increased hydrolysis of InsP3 in the cytosol also showed increased net CO2-fixation and sucrose export into sink tissue and storage of hexoses in the source leaves. The increase in biomass was dependent on the supply of inorganic phosphate in the nutrient medium. Uptake and storage of phosphate was increased in the transgene expressing lines. This suggests that in tomato, increased flux through the inositol phosphate pathway uncoupled phosphate sensing from phosphate metabolism. Altering the second messenger, InsP3, revealed multiple coordinated changes in development and metabolism in tomato that have potential for crop improvement.

The current paper presents the results of an economic evaluation of a new drought-resistant rootstock (M4), capable to maintain in adverse environmental conditions high photosynthetic activity, to accumulate osmotic compounds and to compensate for the accumulation of sodium and chlorine in the grapevines, in two core Italian grapevine growing areas: the North-East and Sicily. After collecting data on quantitative (yield per plant in kg) and qualitative parameters (°Brix, anthocyanins, pH) of experimental vineyards (Cabernet Sauvignon variety) planted using the traditional rootstock 1103P and the innovative M4 rootstock, over a seven-year period, a cost-benefit analysis calculated the effects of replacing the traditional rootstock. The results show that M4 rootstock yields higher net revenues compared to the best situation of 1103P rootstock, roughly in 40% of North-East vineyards and in more than 80% of their Sicilian counterparts. In addition, 14% of North-East vineyards and more t...

This article addresses the issue of insurance coverage for commercial
enterprises as a consequence of the recent spate of droughts in the southwestern United States. This almost two-decade long drought results from increasing temperatures and climate change. The article posits that damage or injury to property and lost profits caused by this wave of droughts may be covered by insurance policies. It focuses on businesses—including tourist attractions such as hotels, motels, boat rental facilities, and others—that are so critical to the economies of the southwestern states. I posit that when these commercial enterprises are, or will be, affected by droughts they may be able to recover their
lost income and profits via two supplementary provisions or riders to their routinely contracted for Commercial General Liability (“CGL”) policies. The “Loss of Business Income” rider and the “Loss of Use” rider have covered losses under other circumstances, including hurricanes, but never for drought affected harms. This article is the first to explore the use of these riders in the context of droughts.

Drought is one of the most frequent natural disasters in Bangladesh which severely affect agrobased
economy and people’s livelihood in almost every year. Characterization of droughts in a systematic way is
therefore critical in order to take necessary actions toward drought mitigation and sustainable development. In
this study, standardized precipitation index is used to understand the spatial distribution of meteorological
droughts during various climatic seasons such as premonsoon, monsoon, and winter seasons as well as cropping
seasons such as Pre-Kharif (March-May), Kharif (May-October), and Rabi (December-February). Rainfall data
collected from 29 rainfall gauge stations located in different parts of the country were used for a period of
50 years (1961-2010). The study reveals that the spatial characteristics of droughts vary widely according to
season. Premonsoon droughts are more frequent in the northwest, monsoon droughts mainly occur in the west
and northwest, winter droughts in the west, and the Rabi and Kharif droughts are more frequent in the north
and northwest of Bangladesh. It is expected that the findings of the study will support drought monitoring and
mitigation activities in Bangladesh.

Environmental stresses, such as shading of the shoot, drought, and soil salinity, threaten plant growth, yield, and survival. Plants can alleviate the impact of these stresses through various modes of phenotypic plasticity, such as shade avoidance and halotropism. Here, we review the current state of knowledge regarding the mechanisms that control plant developmental responses to shade, salt, and drought stress. We discuss plant hormones and cellular signaling pathways that control shoot branching and elongation responses to shade and root architecture modulation in response to drought and salinity. Because belowground stresses also result in aboveground changes and vice versa, we then outline how a wider palette of plant phenotypic traits is affected by the individual stresses. Consequently, we argue for a research agenda that integrates multiple plant organs, responses, and stresses. This will generate the scientific understanding needed for future crop improvement programs aiming...

Droughts are usually destructive when they coincide with crop growing season. Cross-seasonal drought
characterization can better inform drought mitigation
efforts. The present study relies on precipitation data from
the Global Precipitation Climatology Centre to reconstruct
historical droughts during different climatic seasons in
Balochistan province, Pakistan. We identified seasonal
drought events based on the standardized precipitation
index for each season. The distribution of reconstructed
drought events was analyzed to determine their seasonality
and to calculate their return periods. Using these return
periods, we constructed seasonal drought maps. The study
revealed that early winter droughts are frequent in the north
of Balochistan, where the return periods of moderate,
severe, and extreme droughts are 7, 21, and 55 years,
respectively. Severe and extreme late winter droughts are
more frequent in the upper north, with return periods of 16
and 35 years, respectively. Early summer droughts occur
more frequently in the east, returning every 8, 20, and
60 years; late summer droughts occur in the northeast, with
moderate, severe, and extreme droughts returning every 8,
22, and 65 years, respectively. Rabi droughts are more
frequently in the central and northeaster regions of
Balochistan, while more severe kharif droughts occur
primarily in the eastern regions. These seasonal droughts
were found to be positively correlated with variations in the
seasonal rainfall throughout the study area. The findings of
this study contribute to our understanding of seasonal
drought characteristics and help to inform drought mitigation
planning.

Plant growth-promoting rhizobacteria (PGPR) increase the viability and health of host plants when they colonize roots and engage in associative symbiosis (Bashan et al. 2004). In return, PGPR viability is increased by host plant roots by the provision of nutrients and a more protective environment (Richardson et al. in Plant Soil 321:305–339, 2009). The PGPR have great potential in agriculture since the combination of certain microorganisms and plants can increase crop production and increase protection against frost, salinity, drought and other environmental stresses such as the presence of xenobiotic pollutants. But there is a great challenge in combining plants and microorganisms without compromising the viability of either microorganisms or seeds. In this paper, we review how anhydrobiotic engineering can be used for the formulation of biotechnological tools that guarantee the supply of both plants and microorganisms in the dry state. We also describe the application of this technology for the selection of desiccation-tolerant PGPR for polycyclic aromatic hydrocarbons bioremediation, in soils subjected to seasonal drought, by the rhizoremediation process.

Plant acclimation to stress is associated with profound changes in proteome composition. Since proteins are directly involved in plant stress response, proteomics studies can significantly contribute to unravel the possible relationships between protein abundance and plant stress acclimation. In this review, proteomics studies dealing with plant response to a broad range of abiotic stress factors — cold, heat, drought, waterlogging, salinity, ozone treatment, hypoxia and anoxia, herbicide treatments, inadequate or excessive light conditions, disbalances in mineral nutrition, enhanced concentrations of heavy metals, radioactivity and mechanical wounding are discussed. Most studies have been carried out on model plants Arabidopsis thaliana and rice due to large protein sequence databases available; however, the variety of plant species used for proteomics analyses is rapidly increasing. Protein response pathways shared by different plant species under various stress conditions (glycolytic pathway, enzymes of ascorbate–glutathione cycle, accumulation of LEA proteins) as well as pathways unique to a given stress are discussed. Results from proteomics studies are interpreted with respect to physiological factors determining plant stress response. In conclusion, examples of application of proteomics studies in search for protein markers underlying phenotypic variation in physiological parameters associated with plant stress tolerance are given.

Extreme weather conditions with prolonged dry periods and high temperatures as well as heavy rain events can severely influence grapevine physiology and grape quality. The present study evaluates the effects of severe drought stress on selected primary metabolites, polyphenols and volatile metabolites in grapevine leaves. Among the 11 primary metabolites, 13 polyphenols and 95 volatiles which were analyzed, a significant discrimination between control and stressed plants of 7 primary metabolites, 11 polyphenols and 46 volatile metabolites was observed. As single parameters are usually not specific enough for the discrimination of control and stressed plants, an unsupervised (PCA) and a supervised (PLS-DA) multivariate approach were applied to combine results from different metabolic groups. In a first step a selection of five metabolites, namely citric acid, glyceric acid, ribose, phenylacetaldehyde and 2-methylbutanal were used to establish a calibration model using PLS regression ...

Photosynthesis is one of the key processes to be affected by water deficits, via decreased CO2 diffusion to the chloroplast and metabolic constraints. The relative impact of those limitations varies with the intensity of the stress, the occurrence (or not) of superimposed stresses, and the species we are dealing with. Total plant carbon uptake is further reduced due to the concomitant or even earlier inhibition of growth. Leaf carbohydrate status, altered directly by water deficits or indirectly (via decreased growth), acts as a metabolic signal although its role is not totally clear. Other relevant signals acting under water deficits comprise: abscisic acid (ABA), with an impact on stomatal aperture and the regulation at the transcription level of a large number of genes related to plant stress response; other hormones that act either concurrently (brassinosteroids, jasmonates, and salycilic acid) or antagonistically (auxin, cytokinin, or ethylene) with ABA; and redox control of the energy balance of photosynthetic cells deprived of CO2 by stomatal closure. In an attempt to systematize current knowledge on the complex network of interactions and regulation of photosynthesis in plants subjected to water deficits, a meta-analysis has been performed covering >450 papers published in the last 15 years. This analysis shows the interplay of sugars, reactive oxygen species (ROS), and hormones with photosynthetic responses to drought, involving many metabolic events. However, more significantly it highlights (i) how fragmented and often non-comparable the results are and (ii) how hard it is to relate molecular events to plant physiological status, namely photosynthetic activity, and to stress intensity. Indeed, the same data set usually does not integrate these different levels of analysis. Considering these limitations, it was hard to find a general trend, particularly concerning molecular responses to drought, with the exception of the genes ABI1 and ABI3. These genes, irrespective of the stress type (acute versus chronic) and intensity, show a similar response to water shortage in the two plant systems analysed (Arabidopsis and barley). Both are associated with ABA-mediated metabolic responses to stress and the regulation of stomatal aperture. Under drought, ABI1 transcription is up-regulated while ABI3 is usually down-regulated. Recently ABI3 has been hypothesized to be essential for successful drought recovery.