Showing papers on "Shoot published in 2007"
[...]
TL;DR: The dominant fluxes of Zn in the soil-root-shoot continuum are described, including Zn inputs to soils, the plant availability of soluble Zn(2+) at the root surface, and plant uptake and accumulation of ZN.
Abstract: Zinc (Zn) is an essential component of thousands of proteins in plants, although it is toxic in excess. In this review, the dominant fluxes of Zn in the soil-root-shoot continuum are described, including Zn inputs to soils, the plant availability of soluble Zn(2+) at the root surface, and plant uptake and accumulation of Zn. Knowledge of these fluxes can inform agronomic and genetic strategies to address the widespread problem of Zn-limited crop growth. Substantial within-species genetic variation in Zn composition is being used to alleviate human dietary Zn deficiencies through biofortification. Intriguingly, a meta-analysis of data from an extensive literature survey indicates that a small proportion of the genetic variation in shoot Zn concentration can be attributed to evolutionary processes whose effects manifest above the family level. Remarkable insights into the evolutionary potential of plants to respond to elevated soil Zn have recently been made through detailed anatomical, physiological, chemical, genetic and molecular characterizations of the brassicaceous Zn hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri.
1,691 citations
TL;DR: Investigation of variation in the assimilation and translocation of arsenic in commercially farmed temperate rice, wheat, and barley found that the risk posed by As in the human food-chain needs to be considered in the context of anaerobic verses aerobic ecosystems.
Abstract: Paired grain, shoot, and soil of 173 individual sample sets of commercially farmed temperate rice, wheat, and barley were surveyed to investigate variation in the assimilation and translocation of arsenic (As). Rice samples were obtained from the Carmargue (France), Donana (Spain), Cadiz (Spain), California, and Arkansas. Wheat and barleywere collected from Cornwall and Devon (England) and the east coast of Scotland. Transfer of As from soil to grain was an order of magnitude greater in rice than for wheat and barley, despite lower rates of shoot-to-grain transfer. Rice grain As levels over 0.60 microg g(-1) d. wt were found in rice grown in paddy soil of around only 10 microg g(-1) As, showing that As in paddy soils is problematic with respect to grain As levels. This is due to the high shoot/soil ratio of approximately 0.8 for rice compared to 0.2 and 0.1 for barley and wheat, respectively. The differences in these transfer ratios are probably due to differences in As speciation and dynamics in anaerobic rice soils compared to aerobic soils for barley and wheat. In rice, the export of As from the shoot to the grain appears to be under tight physiological control as the grain/shoot ratio decreases by more than an order of magnitude (from approximately 0.3 to 0.003 mg/kg) and as As levels in the shoots increase from 1 to 20 mg/kg. A down regulation of shoot-to-grain export may occur in wheat and barley, but it was not detected at the shoot As levels found in this survey. Some agricultural soils in southwestern England had levels in excess of 200 microg g(-1) d. wt, although the grain levels for wheat and barley never breached 0.55 microg g(-1) d. wt. These grain levels were achieved in rice in soils with an order of magnitude lower As. Thus the risk posed by As in the human food-chain needs to be considered in the context of anaerobic verses aerobic ecosystems.
665 citations
TL;DR: In this article, the authors show that the shoot response to limited soil water supply is not affected by the capacity to generate ABA in the root; however, the response does require ABA biosynthesis and signalling in the shoot.
Abstract: Photosynthesis and biomass production of plants are controlled by the water status of the soil. Upon soil drying, plants can reduce water consumption by minimizing transpiration through stomata, the closable pores of the leaf. The phytohormone abscisic acid (ABA) mediates stomatal closure, and is the assigned signal for communicating water deficit from the root to the shoot. However, our study does not support ABA as the proposed long-distance signal. The shoot response to limited soil water supply is not affected by the capacity to generate ABA in the root; however, the response does require ABA biosynthesis and signalling in the shoot. Soil water stress elicits a hydraulic response in the shoot, which precedes ABA signalling and stomatal closure. Attenuation of the hydraulic response in various plants prevented long-distance signalling of water stress, consistent with root-to-shoot communication by a hydraulic signal.
498 citations
TL;DR: It is suggested conclusively, that protection against the heavy metals toxicity is rendered by these bacterial strains by reducing their uptake and further translocation to shoots in plants and promote the plant growth by other PGP characteristics.
395 citations
TL;DR: The results indicate that mycorrhizal fungus alleviates deleterious effects of saline soils on plant growth that could be primarily related to improved P nutrition.
Abstract: A pot experiment was conducted to examine the effect of arbuscular mycorrhizal fungus, Glomus fasciculatum, and salinity on the growth of Acacia nilotica. Plants were grown in soil under different salinity levels (1.2, 4.0, 6.5, and 9.5 dS m−1). In saline soil, mycorrhizal colonization was higher at 1.2, 4.0, and 6.5 dS m−1 salinity levels in AM-inoculated plants, which decreased as salinity levels further increased (9.5 dS m−1). Mycorrhizal plants maintained greater root and shoot biomass at all salinity levels compared to nonmycorrhizal plants. AM-inoculated plants had higher P, Zn, and Cu concentrations than uninoculated plants. In mycorrhizal plants, nutrient concentrations decreased with the increasing levels of salinity, but were higher than those of the nonmycorrhizal plants. Mycorrhizal plants had greater Na concentration at low salinity levels (1.2, 4.0 dS m−1), which lowered as salinity levels increased (6.5, 9.5 dS m−1), whereas Na concentration increased in control plants. Mycorrhizal plants accumulated a higher concentration of K at all salinity levels. Unlike Na, the uptake of K increased in shoot tissues of mycorrhizal plants with the increasing levels of salinity. Our results indicate that mycorrhizal fungus alleviates deleterious effects of saline soils on plant growth that could be primarily related to improved P nutrition. The improved K/Na ratios in root and shoot tissues of mycorrhizal plants may help in protecting disruption of K-mediated enzymatic processes under salt stress conditions.
374 citations
TL;DR: Drought successively induced shoot growth cessation, stomatal closure, moderate increases in oxidative stress-related compounds, loss of CO2 assimilation, and root growth reduction, indicating that acclimation was dominant over injury.
Abstract: The responses of Populus euphratica Oliv. plants to soil water deficit were assessed by analyzing gene expression, protein profiles, and several plant performance criteria to understand the acclimation of plants to soil water deficit. Young, vegetatively propagated plants originating from an arid, saline field site were submitted to a gradually increasing water deficit for 4 weeks in a greenhouse and were allowed to recover for 10 d after full reirrigation. Time-dependent changes and intensity of the perturbations induced in shoot and root growth, xylem anatomy, gas exchange, and water status were recorded. The expression profiles of approximately 6,340 genes and of proteins and metabolites (pigments, soluble carbohydrates, and oxidative compounds) were also recorded in mature leaves and in roots (gene expression only) at four stress levels and after recovery. Drought successively induced shoot growth cessation, stomatal closure, moderate increases in oxidative stress-related compounds, loss of CO2 assimilation, and root growth reduction. These effects were almost fully reversible, indicating that acclimation was dominant over injury. The physiological responses were paralleled by fully reversible transcriptional changes, including only 1.5% of the genes on the array. Protein profiles displayed greater changes than transcript levels. Among the identified proteins for which expressed sequence tags were present on the array, no correlation was found between transcript and protein abundance. Acclimation to water deficit involves the regulation of different networks of genes in roots and shoots. Such diverse requirements for protecting and maintaining the function of different plant organs may render plant engineering or breeding toward improved drought tolerance more complex than previously anticipated.
364 citations
01 Jan 2007
TL;DR: This chapter provides an overview of the physiological mechanisms by which growth and development of crop plants are affected by salinity, and reproductive development is considered less sensitive to salt stress than vegetative growth.
Abstract: Plant growth and development are adversely affected by salinity – a major environmental stress that limits agricultural production. This chapter provides an overview of the physiological mechanisms by which growth and development of crop plants are affected by salinity. The initial phase of growth reduction is due to an osmotic effect, is similar to the initial response to water stress and shows little genotypic differences. The second, slower effect is the result of salt toxicity in leaves. In the second phase a salt sensitive species or genotype differs from a more salt tolerant one by its inability to prevent salt accumulation in leaves to toxic levels. Most crop plants are salt tolerant at germination but salt sensitive during emergence and vegetative development. Root and shoot growth is inhibited by salinity; however, supplemental Ca partly alleviates the growth inhibition. The Ca effect appears related to the maintenance of plasma membrane selectivity for K over Na. Reproductive development is considered less sensitive to salt stress than vegetative growth, although in wheat salt stress can hasten reproductive growth, inhibit spike development and decrease the yield potential, whereas in the more salt sensitive rice, low yield is primarily associated with reduction in tillers, and by sterile spikelets in some cultivars.
364 citations
TL;DR: There was a significant difference in early growth, dry matter accumulation, pigment, biochemical constituents and proline metabolism among the five varieties of Sunflower (Helianthus annuus L.) plants.
322 citations
TL;DR: It is concluded that compensating for the loss of natural cytokinins in droughted plants interferes with the suppression of shoot growth and the enhancement of root elongation normally seen in d droughtted plants.
Abstract: Cytokinins can promote stomatal opening, stimulate shoot growth and decrease root growth. When soil is drying, natural cytokinin concentrations decrease in association with stomatal closure and a redirection of growth away from the shoots to the roots. We asked if decreased cytokinin concentrations mediate these adaptive responses by lessening water loss and promoting root growth thereby favouring exploration for soil water. Our approach was to follow the consequences for 12-d-old lettuce seedlings of inoculating the growing medium with cytokinin-producing bacteria under conditions of water sufficiency and deficit. Inoculation increased shoot cytokinins as assessed by immunoassay and mass spectrometry. Inoculation also promoted the accumulation of shoot mass and shortened roots while having a smaller effect on root mass. Inoculation did not raise stomatal conductance. The possible promoting effect of these cytokinins on stomatal conductance was seemingly hampered by increases in shoot ABA that inoculation also induced. Inoculation lowered root/shoot ratios by stimulating shoot growth. The effect was greater in non-droughted plants but remained sufficiently strong for shoot mass of inoculated droughted plants to exceed that of well-watered non-inoculated plants. We conclude that compensating for the loss of natural cytokinins in droughted plants interferes with the suppression of shoot growth and the enhancement of root elongation normally seen in droughted plants.
312 citations
TL;DR: It was found that germination was delayed at lower salinity levels and inhibited at higher salinity regimes, and the activity of proline oxidase (PROX) decreased and the γ-glutamyl kinase (γ-GK) activity increased.
288 citations
TL;DR: Based on results, the AM inoculation helps the growth of soybean plants grown in saline conditions when the AM fungus was pre-treated with NaCl with a gradual increase of concentration, and then exposed to a sudden salt stress, their efficiency was increased.
TL;DR: The results indicate the importance of intercropping systems as a promising management practice to alleviate Fe deficiency stress and contributes to better nutrition of plants with Zn, P and K, most probably by affecting biological and chemical process in the rhizosphere.
TL;DR: Seed inoculation with Rhizobium, Bacillus subtilis and Bacillus megaterium, especially dual and triple combinations, may substitute costly NP fertilizers in chickpea production even in cold highland areas such as in Erzurum.
Abstract: Drawbacks of intensive farming practices and environmental costs of nitrogen (N) and phosphorus (P) fertilizers have renewed interest in biofertilizers. A study was conducted in order to investigate seed inoculation of chickpea with Rhizobium, N2-fixing Bacillus subtilis (OSU-142) and P-solubilizing Bacillus megaterium (M-3) in comparison to control and mineral fertilizer application in controlled environment and in field conditions in 2003 and 2004 in Erzurum (29° 55′ N and 41° 16′ E with an altitude of 1950 m), Turkey. In the controlled environment and in the field trials, single, dual, and triple inoculations with Rhizobium, OSU-142, and M-3 significantly increased all the parameters investigated (plant height, shoot, root and nodule dry weight, N%, chlorophyll content, pod number, seed yield, total biomass yield, and seed protein content) compared with the control treatment, equal to or higher than N, P, and NP treatments. In the field all the combined treatments containing Rhizobium were bet...
TL;DR: Based on biomass production, water relations, leaf ions accumulation, leaf and root abscisic acid and stomatal conductance measurements, a specific EC value was identified at which a sharp increase of the shoot and root ABA levels coincided with a decreased sensitivity ofStomatal response to ABA.
TL;DR: It is suggested that the water movement across tonoplast (via AQP) represents a rate-limiting factor for plant vigor under favorable growth conditions and also significantly affect responses of plant to drought, salt and cold stresses.
Abstract: Water movement across cellular membranes is regulated largely by a family of water channel proteins called aquaporins (AQPs). Since several abiotic stresses such as, drought, salinity and freezing, manifest themselves via altering water status of plant cells and are linked by the fact that they all result in cellular dehydration, we overexpressed an AQP (tonoplast intrinsic protein) from Panax ginseng, PgTIP1, in transgenic Arabidopsis thaliana plants to test its role in plant's response to drought, salinity and cold acclimation (induced freezing tolerance). Under favorable conditions, PgTIP1 overexpression significantly increased plant growth as determined by the biomass production, and leaf and root morphology. PgTIP1 overexpression had beneficial effect on salt-stress tolerance as indicated by superior growth status and seed germination of transgenic plants under salt stress; shoots of salt-stressed transgenic plants also accumulated greater amounts of Na(+) compared to wild-type plants. Whereas PgTIP1 overexpression diminished the water-deficit tolerance of plants grown in shallow (10 cm deep) pots, the transgenic plants were significantly more tolerant to water stress when grown in 45 cm deep pots. The rationale for this contrasting response, apparently, comes from the differences in the root morphology and leaf water channel activity (speed of dehydration/rehydration) between the transgenic and wild-type plants. Plants overexpressed with PgTIP1 exhibited lower (relative to wild-type control) cold acclimation ability; however, this response was independent of cold-regulated gene expression. Our results demonstrate a significant function of PgTIP1 in growth and development of plant cells, and suggest that the water movement across tonoplast (via AQP) represents a rate-limiting factor for plant vigor under favorable growth conditions and also significantly affect responses of plant to drought, salt and cold stresses.
TL;DR: The lower Cu accumulation in leaves and higher antioxidant enzyme activities in 31G98 suggested an enhanced tolerance capacity of this cultivar to protect the plant from oxidative damage.
TL;DR: There was higher production of RA and CA in the shoots of AM plants, which was not solely due to better P nutrition, so AMF potentially represent an alternative way of promoting growth of this important medicinal herb.
Abstract: The potential of three arbuscular mycorrhizal fungi (AMF) to enhance the production of antioxidants (rosmarinic and caffeic acids, RA and CA) was investigated in sweet basil (Ocimum basilicum). After adjusting phosphorus (P) nutrition so that P concentrations and yield were matched in AM and non-mycorrhizal (NM) plants we demonstrated that Glomus caledonium increased RA and CA production in the shoots. Glomus mosseae also increased shoot CA concentration in basil under similar conditions. Although higher P amendments to NM plants increased RA and CA concentrations, there was higher production of RA and CA in the shoots of AM plants, which was not solely due to better P nutrition. Therefore, AMF potentially represent an alternative way of promoting growth of this important medicinal herb, as natural ways of growing such crops are currently highly sought after in the herbal industry.
TL;DR: The results of this study suggest that Bacillus M3 and/or OSU-142 and/ or Microbacterium FS01 in combination have the potential to increase the yield, growth and nutrition of apple trees.
TL;DR: Plant growth responses were variable and dependent on bacterial strains, rootstock and cultivar and growth parameters evaluated of young apple trees, suggesting PGPR strains tested in this study have potential to be used for the sustainable and environmentally benign horticultural production.
TL;DR: The long term effects of SA under stress conditions are reported and it is revealed that SA was not as effective as in alleviating abiotic stress as reported in the literature conducted with short-term studies.
TL;DR: The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.
Abstract: The effects of arsenic (As) were investigated on seed germination, root and shoot length and their biomass and some other factors to elucidate the toxicity of As. The results showed low concentrations of As (0–1 mg/kg) stimulated seed germination and the growth of root and shoot, however, these factors all decreased gradually at high concentrations of As (5–20 mg/kg). The contents of O 2 .− , MDA, soluble protein and peroxidase (POD) activity all increased with increasing As concentrations. Soluble sugar content, ascorbate peroxidase (APX), and superoxide dismutase (SOD) activities decreased at low concentrations of As, and increased at high concentrations of As. While acetylsalicylic acid (ASA) and chlorophyll contents, catalase (CAT) activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg, and then decreasing trend. By polyacrylamide gel electrophoresis (PAGE), As induced the expression of POD isozymes of wheat seedlings. As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg. However, As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg. The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.
TL;DR: In this article, the use of a vegetation cover for the management of heavy metal contaminated soils needs prior investigations on the plant species the best sustainable, and behaviors of Trifolium repens and Lolium perenne, growing in a metal-polluted field located near a closed lead smelter, were investigated through Cd, Pb and Zn-plant metal concentrations and their phytotoxicity.
TL;DR: Red redistribution of biomass among vegetative vine parts was significantly related to different indicators of the vine C:N status measured either at the whole-plant (N concentration) or at the organ level (TNC:FAA ratio), suggesting that root-to-shoot biomass partitioning was controlled by some aspect of plant C: N balance.
TL;DR: It is demonstrated that Os BOR1 is required both for efficient B uptake and for xylem loading of B.
Abstract: We describe a boron (B) transporter, Os BOR1, in rice (Oryza sativa). Os BOR1 is a plasma membrane–localized efflux transporter of B and is required for normal growth of rice plants under conditions of limited B supply (referred to as -B). Disruption of Os BOR1 reduced B uptake and xylem loading of B. The accumulation of Os BOR1 transcripts was higher in roots than that in shoots and was not affected by B deprivation; however, Os BOR1 was detected in the roots of wild-type plants under -B conditions, but not under normal conditions, suggesting regulation of protein accumulation in response to B nutrition. Interestingly, tissue specificity of Os BOR1 expression is affected by B treatment. Transgenic rice plants containing an Os BOR1 promoter–β-glucuronidase (GUS) fusion construct grown with a normal B supply showed the strongest GUS activity in the steles, whereas after 3 d of -B treatment, GUS activity was elevated in the exodermis. After 6 d of -B treatment, GUS activity was again strong in the stele. Our results demonstrate that Os BOR1 is required both for efficient B uptake and for xylem loading of B. Possible roles of the temporal changes in tissue-specific patterns of Os BOR1 expression in response to B condition are discussed.
TL;DR: The results showed that germination percentage, germination index, and vigour index of lucerne seeds primed with brassinolide were significantly higher than those of the non-primed seeds under salinity stress in each variety, suggesting that primingLucerne seed with brass inolide at a suitable concentration can improve germination and seedling growth under high-saline soils.
Abstract: Salt stress is an important constraint to lucerne (Medicago sativa L.) production in many parts of the world. Seeds of 3 lucerne varieties, cvv. Victoria, Golden Empress, and Victor, were used to investigate the effects of seed priming with 5 µm/L brassinolide on germination and seedling growth under a high level of salt stress (13.6 dS/m NaCl solution). The results showed that germination percentage, germination index, and vigour index of lucerne seeds primed with brassinolide were significantly higher than those of the non-primed seeds under salinity stress in each variety. Seed priming with brassinolide significantly increased the shoot fresh weight, shoot dry weight, and root dry weight in 2 varieties, and significantly increased the root length and root vigour in each variety. It also significantly increased the activities of antioxidant enzymes, peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), in Victoria and Victor seedlings. During seedling growth, the primed seeds significantly reduced the malondialdehyde (MDA) accumulation. This suggests that priming lucerne seed with brassinolide at a suitable concentration can improve germination and seedling growth under high-saline soils.
TL;DR: Sixteen wheat genotypes including local varieties were tested in completely randomized design with three repeats, showing highly significant differences for all traits in response to the moisture stress.
Abstract: Sixteen wheat genotypes including local varieties were tested in completely randomized design with three repeats. Data were recorded at four different moisture levels by using polyethylene glycol (PEG) 6000 on germination percentage, germination rate index, shoot length, root length, fresh weight of shoot, dry weight of shoot, fresh weight of root, dry weight of root, shoot/root ratio and analysed for significance. The genotypes differ significantly in response to the moisture stress. There were highly significant differences for all traits. PK-18199 gave the maximum germination percentage, germination rate index, shoot length root length, coleoptile length, fresh shoot weight, dry shoot weight, fresh root weight, dry root weight and root/shoot ratio under all four moisture stresses. PK-18175 showed maximum resistance against moisture stress while WAFAQ 2001 showed minimum resistance. AS-2002 and KC033 also gave the better performance under all four moisture levels for most of the traits at seedling stage. 99FJ03 gave maximum root/shoot length ratio while PK 18199 gave minimum value of root/shoot length ratio showing resistance against water stress.
TL;DR: Observations suggest that OsCOW1-mediated IAA biosynthesis plays an important role in maintaining root to shoot ratios and, in turn, affects water homeostasis in rice.
Abstract: Increasing its root to shoot ratio is a plant strategy for restoring water homeostasis in response to the long-term imposition of mild water stress. In addition to its important role in diverse fundamental processes, indole-3-acetic acid (IAA) is involved in root growth and development. Recent extensive characterizations of the YUCCA gene family in Arabidopsis and rice have elucidated that member’s function in a tryptophan-dependent IAA biosynthetic pathway. Through forward- and reverse-genetics screening, we have isolated Tos17 and T-DNA insertional rice mutants in a CONSTITUTIVELY WILTED1 (COW1) gene, which encodes a new member of the YUCCA protein family. Homozygous plants with either a Tos17 or T-DNA-inserted allele of OsCOW1 exhibit phenotypes of rolled leaves, reduced leaf widths, and lower root to shoot ratios. These phenotypes are evident in seedlings as early as 7–10 d after germination, and remain until maturity. When oscow1 seedlings are grown under low-intensity light and high relative humidity, the rolled-leaf phenotype is greatly alleviated. For comparison, in such conditions, the transpiration rate for WT leaves decreases approx. 5- to 10-fold, implying that this mutant trait results from wilting rather than being a morphogenic defect. Furthermore, a lower turgor potential and transpiration rate in their mature leaves indicates that oscow1 plants are water-deficient, due to insufficient water uptake that possibly stems from that diminished root to shoot ratio. Thus, our observations suggest that OsCOW1-mediated IAA biosynthesis plays an important role in maintaining root to shoot ratios and, in turn, affects water homeostasis in rice.
TL;DR: It is demonstrated that seed germination of warm-season grasses is significantly responsive to oxidative conditions and highlights the complex interplay between seed redox status, ABA, ROS and NO in this system.
Abstract: Hydrogen peroxide (H2O2) as a source of reactive oxygen species (ROS) signiWcantly stimulated ger- mination of switchgrass (Panicum virgatum L.) seeds with an optimal concentration of 20 mM at both 25 and 35°C. For non-dormant switchgrass seeds exhibiting diVerent levels of germination, treatment with H 2 O 2 resulted in rapid germination (<3 days) of all germinable seeds as compared to seeds placed on water. Exposure to 20 mM H 2 O 2 elicited simultaneous growth of the root and shoot system, resulting in more uniform seedling development. Seeds of big bluestem (Andropogon gerardii Vitman) and indiangrass (Sorghastrum nutans (L.) Nash) also responded positively to H2O2 treatment, indicating the universality of the eVect of H 2 O 2 on seed germination in warm-season prairie grasses. For switchgrass seeds, abscisic acid (ABA) and the NADPH-oxidase inhibitor, diphenyleneiodonium (DPI) at 20 M retarded germination (radicle emergence), stunted root growth and partially inhibited NADPH-oxidase activ- ity in seeds. H2O2 reversed the inhibitory eVects of DPI and ABA on germination and coleoptile elongation, but did not overcome DPI inhibition of root elongation. Treatment with H 2 O 2 appeared to enhance endogenous production of nitric oxide, and a scavenger of nitric oxide abolished the perox- ide-responsive stimulation of switchgrass seed germination. The activities and levels of several proteins changed earlier in seeds imbibed on H 2 O 2 as compared to seeds maintained on water or on ABA. These data demonstrate that seed ger- mination of warm-season grasses is signiWcantly responsive to oxidative conditions and highlights the complex inter- play between seed redox status, ABA, ROS and NO in this system.
TL;DR: Results indicate that constitutive expression of OsZip4 changes the Zn distribution within rice plants, and that OsZIP4 is a critical Zn transporter that must be strictly regulated.
Abstract: Zinc (Zn), an essential nutrient in cells, plays a vital role in controlling cellular processes such as growth, development, and differentiation. Although the mechanisms of Zn translocation in rice plants (Oryza sativa) are not fully understood, it has recently received increased interest. OsZIP4 is a Zn transporter that localizes to apical cells. Transgenic rice plants overexpressing the OsZIP4 gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter were produced. The Zn concentration in roots of 35S-OsZIP4 transgenic plants was 10 times higher than in those of vector controls, but it was five times lower in shoots. The Zn concentration in seeds of 35S-OsZIP4 plants was four times lower compared with vector controls. Northern blot analysis and quantitative real-time reverse transcription-PCR revealed transcripts of OsZIP4 expression driven by the CaMV 35S promoter in roots and shoots of 35S-OsZIP4 plants, but levels of endogenous OsZIP4 transcripts were low in roots and high in shoots compared with vector controls. Microarray analysis revealed that the genes expressed in shoots of 35S-OsZIP4 plants coincided with those induced in shoots of Zn-deficient plants. These results indicate that constitutive expression of OsZIP4 changes the Zn distribution within rice plants, and that OsZIP4 is a critical Zn transporter that must be strictly regulated.
TL;DR: Salinity had adverse effects not only on the biomass yield and relative growth rate (RGRt), but also on other morphological parameters such as plant height, number of leaves, root length and shoot/root weight ratio.
Abstract: The effect of salinity stress on five cultivars of common bean: Bassbeer, Beladi, Giza 3, HRS 516 and RO21 were evaluated on a sand/peat medium with different salinity levels (0, 50 and 100 mM NaCl) applied 3 weeks after germination for duration of 10 days. Salinity had adverse effects not only on the biomass yield and relative growth rate (RGRt), but also on other morphological parameters such as plant height, number of leaves, root length and shoot/root weight ratio. Photosynthesis, transpiration rate and stomatal conductance were adversely affected in all cultivars. Leaf osmotic potential and leaf turgor varied significantly among cultivars and salt levels. The interaction between cultivars and salt levels for photosynthesis, leaf osmotic potential and leaf turgor was highly significant at day 10 of salt treatment. The Na uptake among the cultivars varied in the order: HRS 516 highest survival rate and no symptoms of salt stress. RO21 was the most susceptible to salinity as it showed severe symptoms of salt stress and very low survival rate.