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1.
PM Visscher 《遗传、选种与进化》1995,27(4):335-345
2.
F. Pax C. Blamey Maria C. Hernandez-Soriano Miaomiao Cheng Caixian Tang David J. Paterson Enzo Lombi Wei Hong Wang Kirk G. Scheckel Peter M. Kopittke 《Plant physiology》2015,169(3):2006-2020
Plant species differ in response to high available manganese (Mn), but the mechanisms of sensitivity and tolerance are poorly understood. In solution culture, greater than or equal to 30 µm Mn decreased the growth of soybean (Glycine max), but white lupin (Lupinus albus), narrow-leafed lupin (Lupin angustifolius), and sunflower (Helianthus annuus) grew well at 100 µm Mn. Differences in species’ tolerance to high Mn could not be explained simply by differences in root, stem, or leaf Mn status, being 8.6, 17.1, 6.8, and 9.5 mmol kg–1 leaf fresh mass at 100 µm Mn. Furthermore, x-ray absorption near edge structure analyses identified the predominance of Mn(II), bound mostly to malate or citrate, in roots and stems of all four species. Rather, differences in tolerance were due to variations in Mn distribution and speciation within leaves. In Mn-sensitive soybean, in situ analysis of fresh leaves using x-ray fluorescence microscopy combined with x-ray absorption near edge structure showed high Mn in the veins, and manganite [Mn(III)] accumulated in necrotic lesions apparently through low Mn sequestration in vacuoles or other vesicles. In the two lupin species, most Mn accumulated in vacuoles as either soluble Mn(II) malate or citrate. In sunflower, Mn was sequestered as manganite at the base of nonglandular trichomes. Hence, tolerance to high Mn was ascribed to effective sinks for Mn in leaves, as Mn(II) within vacuoles or through oxidation of Mn(II) to Mn(III) in trichomes. These two mechanisms prevented Mn accumulation in the cytoplasm and apoplast, thereby ensuring tolerance to high Mn in the root environment.Manganese (Mn) is an essential element for plant growth, but its availability differs greatly in space and time, depending largely on the nature and amount of Mn minerals present and on the soil’s pH and redox potential. With an elaborate chemistry, Mn forms complexes with many organic and inorganic ligands. In soils, Mn has three common oxidation states, Mn(II), Mn(III), and Mn(IV), which form hydrated oxides of mixed valency; Mn is present also as numerous carbonates, silicates, sulfates, and phosphates (Lindsay, 1979). Cationic Mn2+ is the most common form readily absorbed by plant roots (Clarkson, 1988). The toxicity of Mn occurs in acid or waterlogged soils high in Mn minerals.Many plants have mechanisms to accommodate the large differences in Mn2+ in soils. At low available Mn, uptake is increased in some Poaceae by excretion of phytosiderophores of the mugineic acid family (Takahashi et al., 2003), with root phytase exudation also potentially important for acquisition of Mn when Mn availability is limited (George et al., 2014). Mechanisms in other plants include the ability of roots to decrease rhizosphere pH or excrete organic ligands (Neumann and Romheld, 2012; Lambers et al., 2015). However, the relative importance of the many complexes on Mn uptake remains unclear. Toxicity results from high Mn in leaf cell walls (Wissemeier et al., 1992; Wissemeier and Horst, 1992) and through adverse effects on symplastic proteins (Führs et al., 2008). Many plants have mechanisms that limit the adverse effects of high Mn2+ in soils, with numerous ligands involved in its translocation and that of other essential cations (Haydon and Cobbett, 2007). Edwards and Asher (1982) classified a range of crop and pasture species based on their ability to deal with high Mn as those that (1) limit Mn from entering the roots, (2) retain Mn in the roots, or (3) tolerate high Mn in the shoots. At the extreme are plants that hyperaccumulate more than 10,000 mg Mn kg–1 on a dry mass (DM) basis in foliar tissues without metabolic damage (Fernando et al., 2013; van der Ent et al., 2013). Based on 15% DM of leaves, this equates to 12.1 mmol kg–1 on a fresh mass (FM) basis. Celosia argentia, a species adapted to growth on Mn-contaminated mine tailings, accumulated more than 20,000 mg kg–1 Mn in leaves (Liu et al., 2014). Tolerance of high Mn in shoots of some Mn hyperaccumulators has been found to occur through binding to ligands (such as malate or citrate) or sequestration in the vacuole (Fernando et al., 2010).Characteristic symptoms of Mn toxicity include chlorotic and distorted leaves with small necrotic lesions. These lesions have been shown in cowpea (Vigna unguiculata) to contain oxidized Mn and callose (Wissemeier et al., 1992), which forms as a reaction to high intracellular Ca (Kartusch, 2003). The necrotic lesions result mainly from oxidized phenolics (Wissemeier and Horst, 1992) and increased peroxidase activity in the apoplast (Horst et al., 1999). With a critical solution concentration for toxicity (10% growth reduction) of no more than 9 µm Mn, Edwards and Asher (1982) found that cotton (Gossypium hirsutum), bean (Phaseolus vulgaris), cowpea, and soybean (Glycine max) were the most sensitive species of 13 crop and pasture plants grown for 18 to 31 d at constant Mn in solution culture. By contrast, the critical concentration for sunflower (Helianthus annuus) was 7 times higher at 65 µm Mn. Sunflower was the first species found to tolerate high Mn through its sequestration in the trichomes on stems, petioles, and leaves (Blamey et al., 1986). The suspected accumulation of Mn was confirmed using wavelength dispersive x-ray spectroscopy with darkening inferred as due to insoluble higher oxides of Mn. Similarly, high Mn results in darkened trichomes of cucumber (Cucumis sativus) leaves due to oxidized Mn, as shown by the colorimetric benzidine test (Horiguchi, 1987). Watermelon (Citrullus lanatus; Elamin and Wilcox, 1986b), but not muskmelon (Citrullus melo; Elamin and Wilcox, 1986a), grown at high Mn also develops small dark spots around the leaf trichomes. Other species that sequester Mn in the trichomes include common nettle (Urtica dioica; Hughes and Williams, 1988) and Alyssum murale, a Ni hyperaccumulator (Broadhurst et al., 2009; McNear and Küpper, 2014). Thus, some plants in four families, Asteraceae, Cucurbitaceae, Urticaceae, and Brassicaceae, tolerate high Mn in shoots through Mn sequestration in or around the trichomes. The mechanisms may differ, however, because the high Mn present during development of common nettle stinging hairs decreases as plants mature (Hughes and Williams, 1988).Recently developed techniques, including those based on synchrotron radiation, allow investigations of the distribution and speciation of Mn in planta, with most research to date focused on Mn hyperaccumulators (Fernando et al., 2013). For example, Fernando et al. (2010) used x-ray absorption near-edge spectroscopy (XANES) to confirm the widely accepted view that Mn(II) predominates in seven Mn hyperaccumulators. Synchrotron-based x-ray fluorescence microspectroscopy (µ-XRF) was used by McNear and Küpper (2014) to show that the basal region of trichomes of A. murale plants grown at no more than 10 µm Mn contained Mn(II) complexed with phosphate. At 50 µm Mn in solution, however, the increased amount of Mn that had accumulated around the trichomes was present as Mn(III). Few studies, however, have used synchrotron-based techniques to investigate the mechanisms of Mn toxicity and tolerance in agronomic species despite their importance for food production in regions where soils are acidic or intermittently waterlogged. One study on cowpea, with a critical toxicity concentration of only 2 µm Mn (Edwards and Asher, 1982), has shown an accumulation of Mn-citrate in the root cap and associated mucigel within 5 min of exposure to 150 µm Mn (Kopittke et al., 2013).This study aimed to determine the distribution and speciation of Mn in fresh roots, stems, and leaves of four crop species, soybean, white lupin (Lupinus albus), narrow-leafed lupin (Lupinus angustifolius), and sunflower, which differ in tolerance to high Mn. It was hypothesized that Mn distribution and speciation would differ between Mn-sensitive soybean and the three other species. Furthermore, we considered it likely that the Mn tolerance mechanism of sunflower would differ from those of the two lupin species, which do not have darkened trichomes when grown at high Mn. 相似文献
3.
Paulo FP Pimenta Alessandra S Orfano Ana C Bahia Ana PM Duarte Claudia M Ríos-Velásquez Fabrício F Melo Felipe AC Pessoa Giselle A Oliveira Keillen MM Campos Luis Martínez Villegas Nilton Barnabé Rodrigues Rafael Nacif-Pimenta Rejane C Sim?es Wuelton M Monteiro Rogerio Amino Yara M Traub-Cseko José BP Lima Maria GV Barbosa Marcus VG Lacerda Wanderli P Tadei Nágila FC Secundino 《Memórias do Instituto Oswaldo Cruz》2015,110(1):23-47
In the Americas, areas with a high risk of malaria transmission are mainly located in
the Amazon Forest, which extends across nine countries. One keystone step to
understanding the Plasmodium life cycle in Anopheles species from the Amazon Region
is to obtain experimentally infected mosquito vectors. Several attempts to colonise
Ano- pheles species have been conducted, but with only short-lived success or no
success at all. In this review, we review the literature on malaria transmission from
the perspective of its Amazon vectors. Currently, it is possible to develop
experimental Plasmodium vivax infection of the colonised and field-captured vectors
in laboratories located close to Amazonian endemic areas. We are also reviewing
studies related to the immune response to P. vivax infection of Anopheles aquasalis,
a coastal mosquito species. Finally, we discuss the importance of the modulation of
Plasmodium infection by the vector microbiota and also consider the anopheline
genomes. The establishment of experimental mosquito infections with Plasmodium
falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide
interesting models for studying malaria in the Amazonian scenario is important.
Understanding the molecular mechanisms involved in the development of the parasites
in New World vectors is crucial in order to better determine the interaction process
and vectorial competence. 相似文献
4.
Little is known about Mg induced Ca deficiency in alkaline conditions, and the relationship between Mg induced Ca deficiency
and Na induced Ca deficiency. Dilute nutrient solutions (dominated by Mg) were used to investigate the effect of Ca activity
ratio (CAR) on the growth of mungbeans (Vigna radiata (L.) Wilczek cv. Emerald). At pH 9.0, root growth was reduced below a critical CAR of 0.050 (corresponding to 90% relative
root length). Root growth was found to be limited more in Mg solutions than had been previously observed for Na solutions.
Using a CAR equation modified with plasma membrane binding constants (to incorporate the differing antagonistic effects of
Mg and Na), new critical CAR values were calculated for both Na (0.56) and Mg (0.44) dominated solutions. This modified CAR
equation permits the calculation of CAR irrespective of the dominant salt present. 相似文献
5.
Rhizotoxic effects of many trace metals are known, but there is little information on recovery after exposure. Roots of 3-d-old cowpea (Vigna unguiculata (L.) Walp. cv. Caloona) seedlings were grown for 4 or 12 h in solutions of 960 μM Ca and 5 μM B at two concentrations (which reduce growth by 50 or 85%) of nine trace metals that rupture the outer layers of roots. Measured concentrations were 34 or 160 μM Al, 0.6 or 1.6 μM Cu, 2.2 or 8.5 μM ?Ga, 2.3 or 12 μM Gd, 0.8 or 1.9 μM Hg, 1.0 or 26 μM In, 2.4 or 7.3 μM La, 1.8 or 3.8 μM Ru, and 1.3 or 8.6 μM Sc. Roots were rinsed, transferred to solutions free of trace metals, and regrowth monitored for up to 48 h. Recovery from exposure to Hg occurred within 4 h, but regrowth was delayed for ≥?12 h with Al, Ga, or Ru. There was poor regrowth after 4 or 12 h exposure to Cu, Gd, In, La, or Sc. Roots recovered after being grown for 12 to 48 h in 170 μM Al, 5.1 μM? Ga, 2.0 μM Hg, or 1.4 μM Ru, but the extent of recovery was reduced with longer exposure time. Microscopy showed marked differences in symptoms on roots recovering from exposure to the various trace metals. Differences in (i) concentrations that are toxic, (ii) ability of roots to recover, (iii) time for recovery to occur, and (iv) symptoms that develop, suggest that each trace metal has a unique combination of rhizotoxic effects. 相似文献
6.
Shinichiro Maruyama Toshinobu Suzaki Andreas PM Weber John M Archibald Hisayoshi Nozaki 《BMC evolutionary biology》2011,11(1):105
Background
Euglenophytes are a group of photosynthetic flagellates possessing a plastid derived from a green algal endosymbiont, which was incorporated into an ancestral host cell via secondary endosymbiosis. However, the impact of endosymbiosis on the euglenophyte nuclear genome is not fully understood due to its complex nature as a 'hybrid' of a non-photosynthetic host cell and a secondary endosymbiont. 相似文献7.
A Maarten J Kootstra Hendrik H Beeftink Elinor L Scott Johan PM Sanders 《Biotechnology for biofuels》2009,2(1):31-14
Background
In this study, the dilute maleic acid pretreatment of wheat straw is optimized, using pretreatment time, temperature and maleic acid concentration as design variables. A central composite design was applied to the experimental set up. The response factors used in this study are: (1) glucose benefits from improved enzymatic digestibility of wheat straw solids; (2) xylose benefits from the solubilization of xylan to the liquid phase during the pretreatment; (3) maleic acid replenishment costs; (4) neutralization costs of pretreated material; (5) costs due to furfural production; and (6) heating costs of the input materials. For each response factor, experimental data were fitted mathematically. After data translation to €/Mg dry straw, determining the relative contribution of each response factor, an economic optimization was calculated within the limits of the design variables. 相似文献8.
Although it is well known that high Na concentrations induce Ca deficiency in acidic conditions, the effect of high pH on
this competitive mechanism is not so well understood. The effect of Ca activity ratio (CAR) and pH on the Ca uptake of mungbeans
(Vigna radiata (L.) Wilczek cv. Emerald) and Rhodes grass (Chloris gayana cv. Pioneer) in Na dominated solution cultures and in soil was investigated. Changes in pH in the alkaline range were shown
not to affect the critical CAR of 0.024 (corresponding to 90% relative root length) for mungbeans grown in solution culture.
Results from soil grown mungbeans confirmed those from solution culture, with a critical CAR of 0.025. A critical CAR of 0.034
was also established for soil grown Rhodes grass. The similarity of critical values established for mungbeans and Rhodes grass
in solution culture and soil justifies the use of both solution culture and soil solution measurement as techniques for studying
plant growth and limitations across plant species. 相似文献
9.
Peter M. Kopittke Enzo Lombi Brigid A. McKenna Peng Wang Erica Donner Richard I. Webb F. Pax C. Blamey Martin D. de Jonge David Paterson Daryl L. Howard Neal W. Menzies 《Physiologia plantarum》2013,147(4):453-464
The phytotoxicity of Mn is important globally due to its increased solubility in acid or waterlogged soils. Short‐term (≤24 h) solution culture studies with 150 µM Mn were conducted to investigate the in situ distribution and speciation of Mn in apical tissues of hydrated roots of cowpea [Vigna unguiculata (L.) Walp. cv. Red Caloona] using synchrotron‐based techniques. Accumulation of Mn was rapid; exposure to 150 µM Mn for only 5 min resulting in substantial Mn accumulation in the root cap and associated mucigel. The highest tissue concentrations of Mn were in the root cap, with linear combination fitting of the data suggesting that ≥80% of this Mn(II) was associated with citrate. Interestingly, although the primary site of Mn toxicity is typically the shoots, concentrations of Mn in the stele of the root were not noticeably higher than in the surrounding cortical tissues in the short‐term (≤24 h). The data provided here from the in situ analyses of hydrated roots exposed to excess Mn are, to our knowledge, the first of this type to be reported for Mn and provide important information regarding plant responses to high Mn in the rooting environment. 相似文献
10.