Preliminary results from a microscopic examination on the effects of aluminium on the root tips of wheat

Wheeler, D. M.; Wild, David; Edmeades, D. C.

doi:10.1007/bf00011999

Cited by 2 publications

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References 7 publications

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“…The changes observed are consistent with those reported previously in wheat (Wheeler et al, 1992; Copeland, 1994) and in Zea mays L. (Bennet et al, 1985). The different wali messages were found to accumulate i n different areas of t h e root (Fig.…”

Section: Dlscusslonsupporting

confidence: 93%

Aluminum-Induced Genes (Induction by Toxic Metals, Low Calcium, and Wounding and Pattern of Expression in Root Tips)

1995

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We have investigated the response of four AI-induced genes (walil, -3, -4, and -5) from wheat (Triticum aestivum L.) to other stresses. The relative transcript levels of walil (encoding a plant metallothionein-like protein), wali3 and wali5 (putative BowmanBirk proteinase inhibitors), and wali4 (phenylalanine ammoniaiyase) increased in root tips of wheat after 2-d treatments with toxic levels of ali other metals tested (Cd, Fe, Zn, Cu, Ca, In, and La). l h e expression levels of walil, -3, -4, and -5 also increased in the root tips of plants grown in the presence of low levels of Ca (10 PM). The transcript levels of walil, -3, and -5 increased in wounded leaf and root tissue, whereas the transcript levels of wali4 increased only in wounded leaves. The site of expression of walil, -3, and -5 in root tips was identified using in situ hybridization. walil was expressed predominantly in the meristematic tissue of the root tip, whereas wali3 and wali5 were expressed predominantly in the cortical tissue of the root. Some changes in the site of expression of these genes were evident in the roots of AI-treated plants.A1 in soils becomes soluble under acidic conditions (below pH 51, causing an inhibition of root elongation and subsequently of plant growth (Clarkson, 1965). The mitotic activity of root tip cells decreases (Clarkson, 1965) and the root tip thickens, primarily due to an increase in the size of the cortical cells (Bennet et al., 1985). To further our understanding of how plants respond to Al, genes whose expression is affected by A1 toxicity have been identified.Previously we isolated seven cDNA clones (walil-wali7) whose transcripts accumulate with A1 treatment in wheat (Triticum aestivum L.) (Snowden and Gardner, 1993;Richards et al., 1994). Six of these genes show an Alinduced increase in transcript levels in two different wheat cultivars: Warigal (Al-sensitive) and Waalt (Al-tolerant). In contrast, A1 induction of the seventh gene, wali2, by A1 stress occurred only in Warigal.walil encodes a plant metallothionein-like protein, homologous to genes isolated from a number of other plant '

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Section: Dlscusslonsupporting

confidence: 93%

Aluminum-Induced Genes (Induction by Toxic Metals, Low Calcium, and Wounding and Pattern of Expression in Root Tips)

1995

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Interaction Between Silicon and Aluminum in Triticum Aestivum L. (Cv. Celtic)

et al. 1997

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Seedlings ofTriticum aestivumL. (cv. Celtic) were suspended in plastic tubs containing 500 μmol L−1Ca(NO3)2and 31 μmol L−1KC1 as background solution. A1C13(0 and 100 μmol L−1) and Na2SiO3.5H2O (0 and 2000 μmol; L−1) were added to this basal nutrient medium, and solution pH was set at 4.2 or 4.6. Tubs were aerated and supplied with a continuous flow of pH-adjusted test solution. Plants were grown for 4 d in a growth cabinet at 25 °C with a 16 h photoperiod. At pH 4.2 and 4.6 root length of the seedlings was inhibited at 100 μmol L−1Al. An amelioration of Al-induced toxicity symptoms was observed in the 100 μmol L−1A1/2000 μmol L−1Si treatment at pH 4.6, but not at pH 4.2. Both the shoot (S) and root (R) dry weight of seedlings treated with 100 μmol L−1Al were reduced when compared with controls. Treatment with Al increased S:R ratios, and this effect was ameliorated by Si, but only at pH 4.6.Al content of roots treated with 100 μmol L−1Al or 100 μmol L−1Al/2000 μmol L−1Si increased significantly when compared with controls. More Al accumulated in the roots of seedlings of the 100 μmol L−1Al/2000 μmol L−1Si treatment than in the 100 μmol L−1treatment. Al treatment reduced root and shoot K concentrations under both pH regimes, and Si did not ameliorate this effect. Al treatment had little effect on seedling Ca levels.Three treatments were selected for a microanalytical investigation of the basal third of the root, and the zone 3.5 mm behind the root tip: 2800 μmol L−1Si; 75 μmol Al; and a combination of the two. When plants were grown in 2800 μmol L−1Si the major silica deposition sites in the roots were the endodermal walls. In the 75 μmol L−1Al treatment, Al was mainly located in the epidermal and hypodermal walls. Al treatment caused a leakage of phosphorus into these cell walls. When both 2800 μmol L−1and 75 μmol L−1Al were present in the nutrient solution, only Si was deposited in the endodermal walls, while both elements were present in the epidermal walls. Leakage of phosphorus appeared to be prevented in the presence of Si.

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Preliminary results from a microscopic examination on the effects of aluminium on the root tips of wheat

Cited by 2 publications

References 7 publications

Aluminum-Induced Genes (Induction by Toxic Metals, Low Calcium, and Wounding and Pattern of Expression in Root Tips)

Aluminum-Induced Genes (Induction by Toxic Metals, Low Calcium, and Wounding and Pattern of Expression in Root Tips)

Interaction Between Silicon and Aluminum in Triticum Aestivum L. (Cv. Celtic)

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