Functional Plant Biology

Water deficit stress is a major constraint to chickpea yield and there is need to identify the physiological and biochemical indices of drought tolerance. Water deficit stress tolerance in chickpea is mediated by antioxidative defence mechanisms in different underground (roots and nodules) and aboveground (leaves, pod walls and seeds) tissues. The study can be used for enhancing the sustainability of agricultural practices in low-moisture soils.

Increased precipitation during warmer winters may lead to low-temperature waterlogging. The aim of the study was to evaluate the effects of cold waterlogging on photosynthesis: it was shown that different photosynthetic acclimation systems are activated. The results indicate that the predicted climatic changes may modify cold acclimation process in plants.

Nitric oxide (NO) is an endogenous signaling molecule mediating plant responses to environmental constraints. The effect of exogenous NO was investigated in Cakile maritima seedlings under water deficit stress, using sodium nitroprusside as NO donor. NO supply mitigated the impact of water deficit stress on C. maritima by the stimulation of proline biosynthesis and the reduction of oxidative damage.

Responses to salinity and drought were analysed in three rush species with different degrees of salt tolerance. The most tolerant species – sea rush and spiny rush – were more efficient in inhibition of the transport of toxic ions to the aerial part of the plants, activate potassium transport at high external salt concentrations, and accumulated much higher levels of proline as an osmoprotectant. These findings contribute to elucidate relevant stress tolerance mechanisms in Juncus species.

The effects of high temperature on reproductive growth have been a focus in climate change research. However, concomitant increases in air and soil temperatures will substantially reduce coleoptile elongation, limiting wheat establishment, particularly when wheat is sown early into deeper soil moisture. Improved management, together with selection of new and existing alleles for greater coleoptile length, will be required to avoid crop establishment failures in future climates.

Cadmium (Cd) is the main heavy metal that limits plant productivity worldwide. Antioxidant mechanisms of the four citrus rootstocks exposed to environmentally-realistic concentrations of Cd were characterised. We found that roots differ in the ability to cope Cd-induced oxidative stress through differences in metabolic and antioxidant events involving carbohydrates, soluble and polymerised phenolics, lipid peroxidation and reactive oxygen species accumulation. We propose a hypothetical model to explain differences observed in this study.

Vegetative and reproductive growth of many plant species is detrimentally affected by high temperatures, but it is not known just how high the temperatures have to be to cause damage. In this work, a hydrocooling system was used to control grapevine canopy temperatures at set points. The results showed many processes such as dry matter accumulation were optimal at 30°C, therefore, where some depreciation was evident suggested a threshold temperature was 35°C and exposure to 40°C was distinctly detrimental.

Plants exhibiting crassulacean acid metabolism are highly heat sensitive in the dark when malic acid has accumulated in cell vacuoles overnight. The present investigation on Clusia and Agave shows that light effectively eliminates the increased heat sensitivity seen at high acid levels. It is concluded that in the dark, heat-induced efflux of malic acid from vacuoles causes damage to leaf tissue, particularly to chloroplasts, whereas under illumination, damage is avoided by turnover of the acid during photosynthetic metabolism.

This paper investigates effect of salinity stress and K⁺ nutrition on photosynthetic parameters of isolated chloroplasts and shows that chloroplasts’ ability to regulate ion transport across the envelope and thylakoid membranes play a critical role in leaf photosynthetic performance under salinity.

Very little is known about the adaptation mechanism of A. littoralis under saline conditions. In this study, we investigated salt tolerance mechanisms adopted by this halophyte. Proteomic analyses revealed that the reduction of proteins related to photosynthesis and induction of proteins involved in glycolysis activity and TCA cycle and energy metabolism could be the main mechanisms for salt tolerance in A. littoralis.

In this work, we demonstrated the natural variation in mechanisms for protection against salt stress in pepper varieties. NaCl-induced K⁺ and H⁺ efflux in roots was also studied by ion-selective microelectrodes under application of pharmacological agents. Pharmacological analysis indicated that the NaCl-induced K⁺ leakage was mediated by TEA+-sensitive KOR channels but not by NSCC channels and we present evidence for participation of proline, and HAK K⁺ transporter for maintaining K⁺ homeostasis under salt stress.

Salt stress has a high impact on crop yield, with current global annual losses being around US$27 billion. Among horticulture crops, cucumber (Cucumis sativus) is considered a moderately salt-sensitive species. Here, we report a study on two cultivars of cucumber with different tolerance to salt. The ability of roots to retain K and produce reactive O species is important for salt tolerance screening and plant breeding programmes.

Dehydrin proteins play a key role in stress tolerance in plants. The aim of this work was to highlight the role of the different conserved domains of a wheat dehydrin (DHN-5) overexpressed in Arabidopsis transgenic plants. We showed that DHN-5 via its K-segments may play a role in the improvement of tolerance to abiotic and biotic stress. It remains to be seen the effect of the over-expressing of DHN-5 in the development of crops with multiple stress tolerances.

In this study we isolated the SlBAH1 gene from tomato. SlBAH1 possesses E3 ubiquitin ligase enzyme activity. SlBAH1 was localised in the nucleus, cytoplasm and plasma membrane. SlBAH1-silencing enhanced resistance to Botrytis cinerea.

The next step in wheat climate change adaptation research is to evaluate responses of individual cultivars to elevated CO₂. This will require the evaluation of large numbers of genotypes, and for practical reasons, preliminary studies are most likely to be conducted in controlled environments with container-grown plants. However, this might create problems or reduce the ability to detecting true cultivar responses.

Understanding how crops respond to environmental stress will expand our capacity to improve production. We explore the physiological and chemical responses of Phaseolus vulgaris L. to different stresses, identifying changes in the abundance of protective metabolites. We identify shifts in C allocation among metabolite pools and, through measuring compound-specific isotope abundance, identify the potential for changes in biochemical fractionation that may impact predictions of intrinsic water use efficiency. Our findings indicate biochemical traits that could help improve strategies to develop crops that can withstand adverse conditions.

As crops are permanently threatened by pests and pathogens, breeding of resistant varieties is an important strategy to control these risks. During the breeding processes, an effective and reliable evaluation of promising candidates is necessary, but often difficult and laborious; therefore, a sensor-based method was used, revealing spatial and temporal differences in Cercospora leaf spot resistance of sugar beet lines with closely related genetic backgrounds. The method proved to be highly sensitive to quantitative differences in resistance and may improve resistance breeding.

Micro-scale phenotyping analysis of vascular bundles is valuable for phenotypic identification of germplasm resources. We developed a sample preparation protocol for micro-CT imaging of corn stalks, and designed an automatic image processing pipeline for phenotyping analysis of vascular bundles. These methods have potential to improve the throughput and quality of micro-scale phenotypic traits, and are expected to be useful in genetic and physiological studies to discover links between stalk anatomy and functions such as water transportation efficiency, mechanical properties.

The greenbug can cause significant economic damage to several cultivated grasses. Peroxidases are a class of plant enzymes that have been associated with resistance to aphids. An equivalent region of genomes of three cultivated grasses contained evolutionarily-related peroxidase genes that were induced in response to greenbug herbivory, potentially linking this genomic hotspot to insect resistance.

The need for increased crop yields is becoming urgent as the amount of arable land available is reduced and environmental factors worsen, however, plant phenotyping has been identified as a key bottleneck in the process of improving crop yields. Here we review approaches to 3D shoot reconstruction to improve phenotyping using image-based methods. An automated system capable of producing three-dimensional (3D) models of plants would significantly aid phenotyping practice, increase accuracy and repeatability of measurements and potentially aid the process of improved crop yields.

Cereal yield is limited by the rate of starch biosynthesis and previous experiments have focussed on increasing starch in leaves or seeds. This study demonstrates that increasing leaf and seed starch simultaneously by using tissue specific overexpression of AGPase enhances yield more than with leaf or seed starch alone. Our results demonstrate that maximum yield in cereals are achievable with high level overexpression of rate-limiting enzymes in more than one tissue.

Plant phenotyping platforms allow high-throughput experiments, and facilitate the study of plant growth to precisely monitored watering conditions. This study describes the disturbing effect of pot size on oilseed rape responses to water deficit. Our results raise the awareness of the need to carefully consider the pot size when designing protocols of high-throughput phenotyping experiments.

Co-ordination between leaf vein and stomatal densities is required to achieve maximum photosynthetic yield. In this work we tested the generality of this co-ordination and found a weak correlation between vein and stomatal densities across 105 angiosperm tree species across altitudes from 800 to 2600 m in South-west China. This reveals decoupled adaptation in leaf venation and stomatal characteristics along a large altitudinal gradient.

Leaf trait correlations are important for understanding carbon–water–nutrient couplings in plant functional biology. We investigated leaf hydraulics and economic traits for 10 Chinese temperate tree species, and found a tight co-ordination between these two suits of traits. This co-ordinated performance plays an important role in determining plant ecological strategies and supports the ‘fast–slow’ leaf economics spectrum.

Iron toxicity is harmful to plants. The aim of this study was to characterise the mechanisms underlying differential Fe-toxicity tolerance in wheat. From our results we propose that Fe-toxicity tolerance in wheat is shoot based and is mainly associated with the regulation of translocation and chelation of Fe together with increased antioxidant defence in shoots.