A thorough understanding of ionic detoxification and homeostasis is imperative for improvement of salt tolerance in crops. However, the homeostasis of elements and their relationship to metabolites ...under salt stress have not been fully elucidated in plants. In this study, Tibetan wild barley accessions, XZ16 and XZ169, differing in salt tolerance, and a salt-tolerant cultivar CM72 were used to investigate ionomic profile changes in tissues in response to 150 and 300 mM NaCl at the germination and seedling stages. At the germination stage, the contents of Ca and Fe significantly decreased in roots, while K and S contents increased, and Ca and Mg contents decreased in shoots, after 10 d of treatment. At the seedling stage, the contents of K, Mg, P and Mn in roots and of K, Ca, Mg and S in shoots decreased significantly after 21 d of treatment. Moreover, Na had a significant negative correlation with metabolites involved in glycolysis, α-ketoglutaric acid, maleic acid and alanine in roots, and metabolites associated with the tricarboxylic acid (TCA) cycle, sucrose, polyols and aspartate in leaves. The salt-tolerant genotypes XZ16 and CM72 showed a lower Na content in tissues, and less reduction in Zn and Cu in roots, of Ca, Mg and S in leaves, and shoot DW than the sensitive genotype XZ169, when exposed to a higher salt level. The results indicated that restriction of Na accumulation and rearrangement of nutrient elements and metabolites in barley tissues are possibly attributable to development of salt tolerance.
Sustainable food production in protected cropping is increasing rapidly in response to global climate change and population growth. However, there are significant knowledge gaps regarding energy ...consumption while achieving optimum environmental conditions for greenhouse crop production. A capsicum crop cultivated in a high-tech greenhouse facility in Australia was analysed in terms of relationships between key environmental variables and the comparative analysis of energy consumption during different seasons. We showed that daily energy consumption varied due to the seasonal nature of the external environment and maintenance of optimal growing temperatures. Total power consumption reported throughout the entire crop cycle for heating (gas hot water system) and cooling (pad and fan) was 12,503 and 5183 kWh, respectively; hence, heating consumed ca. 70% of the total energy requirement over the 8-month growing period (early spring to late autumn) in the greenhouse facility. Regressions of daily energy consumption within each season, designated either predominantly for heating or cooling, indicated that energy consumption was 14.62 kWh per 1 °C heating and 2.23 kWh per 1 °C cooling. Therefore, changing the planting date to late spring is likely to significantly reduce heating energy costs for greenhouse capsicum growers in Australia. The findings will provide useful guidelines to maximise the greenhouse production of capsicum with better economic return by taking into consideration the potential optimal energy saving strategy during different external environment conditions and seasons.
•HvEXPA1 is an Al-inducible expansin located in plasma membrane.•Novel expansin gene HvEXPA1 involved in root cell elongation.•Al-induced HvEXPA1 only found in root tips of Al-tolerant wild barley ...XZ16.•Silencing HvEXPA1 inhibits root cell elongation of XZ16 in the absence of Al.•HvEXPA1 silenced lines accumulated less Al in root cell wall of XZ16.
Acid soil and the associated aluminum (Al) toxicity are one of major abiotic stresses, costing global agriculture significant production loss in major crops such as barley. Expansins are known as cell wall loosening proteins that regulate the loosening process of plant cell wall. However, the functional relationship between expansins and Al stress in barley was still poorly understood. In this study, we functionally characterized an Al inducible expansin gene, HvEXPA1, using a range of molecular and physiological approaches. There was a significant genotypic difference in Al-induced gene expression of HvEXPA1, where both Al-tolerant genotypes of Tibetan wild barley XZ16 and cv. Dayton showed significant upregulation but not in Al-sensitive wild barley XZ61. In XZ16, a significant upregulation of HvEXPA1 is exclusively induced by Al in low pH (4.3) at root tips, but not by low pH (4.3), normal apoplastic pH (5.8) or other metals ions such as Cr or La. Subcellular localization analysis indicated that HvEXPA1 is located in the plasma membrane. Bioinformatic analysis indicated that HvEXPA1 carried 3 domains and conserved 3D structure among seven genera. Barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) of HvEXPA1 led to a significant decrease in root length and root dry weight under both of control and 200 μM Al treatments, but the inhibition in root cell length only recorded in control condition. Interestingly, reduced Al concentration via silencing of HvEXPA1 was recorded only in root cell wall but not in cell sap. Our results indicate that HvEXPA1 is an Al-inducible expansin gene, which participates in the root cell elongation and probably influences the Al content through regulating root cell wall loosening in barley.
Greenhouse horticulture (protected cropping) is essential in meeting increasing global food demand under climate change scenarios by ensuring sustainability, efficiency, and productivity. Recent ...advances in cover materials and photovoltaic technologies have been widely examined in greenhouses to improve light transmission and solar energy capture with promoting energy-saving. We review the studies on advanced greenhouse cover materials with variable light transmittance, the effects of which on leaf photosynthesis, physiology, and yield. We provide insights into the potential key biological processes of crops responding to these light changes, specifically light receptors, signal transduction, nutrient biosynthesis pathways (e.g., carotenoids, antioxidant compounds) during fruit development and ripening. A better understanding of greenhouse cover materials with a focus towards energy-efficient cover materials equipped in greenhouse is an opportunity for better yield and higher nutrient products production in vegetables in response to global climate challenges. Interdisciplinary research on the application of novel cover materials in greenhouses and biological investigation of light-induced physiology and nutrient formation in vegetables may promote yield and health attributes for protected cultivation of vegetables with energy use efficiency.
Wound healing is a complex and error‐prone process. Wound healing in adults often leads to the formation of scars, a type of fibrotic tissue that lacks skin appendages. Hypertrophic scars and keloids ...can also form when the wound‐healing process goes wrong. Leptin (Lep) and leptin receptors (LepRs) have recently been shown to affect multiple stages of wound healing. This effect, however, is paradoxical for scarless wound healing. On the one hand, Lep exerts pro‐inflammatory and profibrotic effects; on the other hand, Lep can regulate hair follicle growth. This paper summarises the role of Lep and LepRs on cells in different stages of wound healing, briefly introduces the process of wound healing and Lep and LepRs, and examines the possibility of promoting scarless wound healing through spatiotemporal, systemic, and local regulation of Lep levels and the binding of Lep and LepRs.
Consumption of rice (Oryza sativa L.) is one of the major pathways for heavy metal bioaccumulation in humans over time. Understanding the molecular responses of rice to heavy metal contamination in ...agriculture is useful for eco-toxicological assessment of cadmium (Cd) and its interaction with zinc (Zn). In certain crops, the impacts of Cd stress or Zn nutrition on the biophysical chemistry and gene expression have been widely investigated, but their molecular interactions at transcriptomic level, particularly in rice roots, are still elusive. Here, hydroponic investigations were carried out with two rice genotypes (Yinni-801 and Heizhan-43), varying in Cd contents in plant tissues to determine their transcriptomic responses upon Cd15 (15 µM) and Cd15+Zn50 (50 µM) treatments. High throughput RNA-sequencing analysis confirmed that 496 and 2407 DEGs were significantly affected by Cd15 and Cd15+Zn50, respectively, among which 1016 DEGs were commonly induced in both genotypes. Multitude of DEGs fell under the category of protein kinases, such as calmodulin (CaM) and calcineurin B-like protein-interacting protein kinases (CBL), indicating a dynamic shift in hormonal signal transduction and Ca2+ involvement with the onset of treatments. Both genotypes expressed a mutual regulation of transcription factors (TFs) such as WRKY, MYB, NAM, AP2, bHLH and ZFP families under both treatments, whereas genes econding ABC transporters (ABCs), high affinity K+ transporters (HAKs) and Glutathione-S-transferases (GSTs), were highly up-regulated under Cd15+Zn50 in both genotypes. Zinc addition triggered more signaling cascades and detoxification related genes in regulation of immunity along with the suppression of Cd-induced DEGs and restriction of Cd uptake. Conclusively, the effective integration of breeding techniques with candidate genes identified in this study as well as economically and technologically viable methods, such as Zn nutrient management, could pave the way for selecting cultivars with promising agronomic qualities and reduced Cd for sustainable rice production.
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•Zn helps to sustain physiological functions otherwise retarded by cadmium stress, such as transpiration and photosynthesis.•Strategic allocation of energy to cell survival mechanisms and lignification process along with other Cd-excluding tactics.•Up-regulation of cysteine and methionine metabolism and phyto-hormonal response distinguishes Zn-mediated Cd tolerance.•Co-ordinated up/downstream genes expression involved in Zn-instigated nutrient cross-talk elevates Cd toxicity.
Salinity stress affects global food producing areas by limiting both crop growth and yield. Attempts to develop salinity-tolerant rice varieties have had limited success due to the complexity of the ...salinity tolerance trait, high variation in the stress response and a lack of available donors for candidate genes for cultivated rice. As a result, finding suitable donors of genes and traits for salinity tolerance has become a major bottleneck in breeding for salinity tolerant crops. Twenty-two wild
relatives have been recognized as important genetic resources for quantitatively inherited traits such as resistance and/or tolerance to abiotic and biotic stresses. In this review, we discuss the challenges and opportunities of such an approach by critically analyzing evolutionary, ecological, genetic, and physiological aspects of
species. We argue that the strategy of rice breeding for better Na
exclusion employed for the last few decades has reached a plateau and cannot deliver any further improvement in salinity tolerance in this species. This calls for a paradigm shift in rice breeding and more efforts toward targeting mechanisms of the tissue tolerance and a better utilization of the potential of wild rice where such traits are already present. We summarize the differences in salinity stress adaptation amongst cultivated and wild
relatives and identify several key traits that should be targeted in future breeding programs. This includes: (1) efficient sequestration of Na
in mesophyll cell vacuoles, with a strong emphasis on control of tonoplast leak channels; (2) more efficient control of xylem ion loading; (3) efficient cytosolic K
retention in both root and leaf mesophyll cells; and (4) incorporating Na
sequestration in trichrome. We conclude that while amongst all wild relatives,
is arguably a best source of germplasm at the moment, genes and traits from the wild relatives,
,
, and
, should be targeted in future genetic programs to develop salt tolerant cultivated rice.
Aims
Cadmium (Cd) is a toxic metal in soils and its accumulation in plants poses severe problems to agricultural production and human health. Most of research has focused on the Cd toxicity to ...plants, but reports on Cd co-transport and regulation by the major counter ion Chloride (Cl) is limited. This study aims to understand the mechanisms of the interaction between soil Cl and phytol-toxicity of Cd.
Methods
We utilised soil chemical, plant physiological, biophysical, and molecular approaches to test the hypothesis that Cl transport increases the mobility and phytol-toxicity of Cd to barley.
Results
Cd-sensitive Gairdner utilised high amount of Cl
−
from soil for optimal growth and yield in the control, but this also caused higher tissue Cd uptake and significantly affected photosynthesis in treatments of Cd-Cl combinations. Net ion fluxes from the root mature zone in Cd treatments and relative expression of transporter genes exhibited striking difference between two genotypes. Our results also highlighted evidence that Cd sensitivity is related to higher Cl
−
and Cd
2+
uptake and lower capacity to regulate root ion homeostasis and gene expression.
Conclusions
We present a new finding that soil Cl
−
and Cd availability and Cd uptake and its interaction with other ions play a major role in barley Cd tolerance. These findings will guide future breeding for low Cl
−
uptake genotypes to reduce Cd accumulation for barley grown in Cd contaminated soils and for the economically sound and cleaner production of barley for the global feed, food and brewery industry.
Detrimental impacts of drought on crop yield have tripled in the last 50 years with climate models predicting that the frequency of such droughts will intensify in the future. Silicon (Si) ...accumulation, especially in Poaceae crops such as wheat (
Triticum aestivum
L.), may alleviate the adverse impacts of drought. We have very limited information, however, about whether Si supplementation could alleviate the impacts of drought under field conditions and no studies have specifically manipulated rainfall. Using field–based rain exclusion shelters, we determined whether Si supplementation (equivalent to 39, 78 and 117 kg ha
-1
) affected
T. aestivum
growth, elemental chemistry Si, carbon (C) and nitrogen (N), physiology (rates of photosynthesis, transpiration, stomatal conductance, and water use efficiency) and yield (grain production) under ambient and drought (50% of ambient) rainfall scenarios. Averaged across Si treatments, drought reduced shoot mass by 21% and grain production by 18%. Si supplementation increased shoot mass by up to 43% and 73% in ambient and drought water treatments, respectively, and restored grain production in droughted plants to levels comparable with plants supplied with ambient rainfall. Si supplementation increased leaf-level water use efficiency by 32–74%, depending on Si supplementation rates. Water supply and Si supplementation did not alter
concentrations
of C and N, but Si supplementation increased shoot C
content
by 39% and 83% under ambient and drought conditions, respectively. This equates to an increase from 6.4 to 8.9 tonnes C ha
-1
and from 4.03 to 7.35 tonnes C ha
-1
under ambient and drought conditions, respectively. We conclude that Si supplementation ameliorated the negative impacts of drought on
T. aestivum
growth and grain yield, potentially through its beneficial impacts on water use efficiency. Moreover, the beneficial impacts of Si on plant growth and C storage may render Si supplementation a useful tool for both drought mitigation and C sequestration.
Arid/semi-arid and coastal agricultural areas of the world are especially vulnerable to climate change-driven soil salinity. Salinity tolerance in plants is a complex trait, with salinity negatively ...affecting crop yield. Plants adopt a range of mechanisms to combat salinity, with many transporter genes being implicated in Na+-partitioning processes. Within these, the high-affinity K+ (HKT) family of transporters play a critical role in K+ and Na+ homeostasis in plants. Among HKT transporters, Type I transporters are Na+-specific. While Arabidopsis has only one Na + -specific HKT (AtHKT1;1), cereal crops have a multiplicity of Type I and II HKT transporters. AtHKT1; 1 (Arabidopsis thaliana) and HKT1; 5 (cereal crops) ‘exclude’ Na+ from the xylem into xylem parenchyma in the root, reducing shoot Na+ and hence, confer sodium tolerance. However, more recent data from Arabidopsis and crop species show that AtHKT1;1/HKT1;5 alleles have a strong genetic association with ‘shoot sodium accumulation’ and concomitant salt tolerance. The review tries to resolve these two seemingly contradictory effects of AtHKT1;1/HKT1;5 operation (shoot exclusion vs shoot accumulation), both conferring salinity tolerance and suggests that contrasting phenotypes are attributable to either hyper-functional or weak AtHKT1;1/HKT1;5 alleles/haplotypes and are under strong selection by soil salinity levels. It also suggests that opposite balancing mechanisms involving xylem ion loading in these contrasting phenotypes exist that require transporters such as SOS1 and CCC. While HKT1; 5 is a crucial but not sole determinant of salinity tolerance, investigation of the adaptive benefit(s) conferred by naturally occurring intermediate HKT1;5 alleles will be important under a climate change scenario.
•High-affinity K+ (HKT) family of transporters play a critical role in K+ and Na+ homeostasis in plants.•HKT1/HKT1;5 operate in both shoot Na + exclusion and shoot Na + accumulation.•Contrasting phenotypes are attributable to either hyper-functional or weak HKT1/HKT1;5 alleles/haplotypes.
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