Gibberellin Biosynthesis Mutations and Root Development in Pea

Yaxley, Julian R.; Ross, John J.; Sherriff, Leanne J.; Reid, James B.

doi:10.1104/pp.125.2.627

Cited by 129 publications

(110 citation statements)

References 27 publications

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“…Several examples of the effects of gibberellins applied directly to roots have been reported (Tanimoto, 1994;Yaxley et al, 2001). In the present study, gibberellins applied to the shoot affected XSP30 gene expression in roots (Figs.…”

Section: Possible Physiological Function(s) Of Xsp30supporting

confidence: 52%

Possible Involvement of Leaf Gibberellins in the Clock-Controlled Expression of XSP30, a Gene Encoding a Xylem Sap Lectin, in Cucumber Roots

et al. 2003

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Root-produced organic compounds in xylem sap, such as hormones and amino acids, are known to be important in plant development. Recently, biochemical approaches have revealed the identities of several xylem sap proteins, but the biological functions and the regulation of the production of these proteins are not fully understood. XYLEM SAP PROTEIN 30 kD (XSP30), which is specifically expressed in the roots of cucumber (Cucumis sativus), encodes a lectin and is hypothesized as affecting the development of above-ground organs. In this report, we demonstrate that XSP30 gene expression and the level of XSP30 protein fluctuate in a diurnal rhythm in cucumber roots. The rhythmic gene expression continues for at least two or three cycles, even under continuous light or dark conditions, demonstrating that the expression of this gene is controlled by a circadian clock. Removal of mature leaves or treatment of shoots with uniconazole-P, an inhibitor of gibberellic acid (GA) biosynthesis, dampens the amplitude of the rhythmic expression; the application of GA negates these effects. These results suggest that light signals perceived by above-ground organs, as well as GA that is produced, possibly, in mature leaves, are important for the rhythmic expression of XSP30 in roots. This is the first demonstration of the regulation of the expression of a clock-controlled gene by GA.The higher plant body consists of functionally specialized organs such as the leaf, stem, flower, and root. Because plants grow in changing environments, it is essential for different organs to interact to ensure that the plant body develops and functions properly. Information transfer between organs is essential for synchronized plant development (Bernier, 1988;Kolek and Kozinka, 1991). A major route for the transfer of materials between organs consists of the vascular bundles, which are composed mainly of the xylem and phloem. Numerous materials are translocated over long distances through these bundles. The xylem is composed mainly of xylem vessels, which form a type of apoplastic space. Organic nutrients, such as amino acids, sugars, and organic acids, as well as water and inorganic nutrients, are transported through the xylem to the aboveground organs (Schurr and Schulze, 1995;Zornoza et al., 1996;Satoh et al., 1998). Interestingly, the roots control aspects of the development of aerial organs, possibly acting via growth-related compounds in the xylem sap (Kinet et al., 1993;Satoh, 1996). For example, cytokinin, abscisic acid, and other growth-related compounds that are synthesized in root tissues are involved in stomatal responses (Else et al., 1995;Liang et al., 1997), leaf senescence (Nooden et al., 1990;Soejima et al., 1992), lateral bud development (Bangerth, 1994; Beveridge et al., 1997), flower bud formation (Kinet et al., 1993), leaf greening , and adventitious root formation (Kuroha et al., 2002).Recently, macromolecules have been found in xylem sap, including oligo-and polysaccharides (Satoh et al., 1992; Campbell et al., 1995) and protei...

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Section: Possible Physiological Function(s) Of Xsp30supporting

confidence: 52%

Possible Involvement of Leaf Gibberellins in the Clock-Controlled Expression of XSP30, a Gene Encoding a Xylem Sap Lectin, in Cucumber Roots

et al. 2003

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“…The reasoning for this was that the roots of the GA biosynthesis mutants le-1 and le-2 (null) are phenotypically similar to wild type and contain similar levels of endogenous GA 20 and GA 1 to wild type, in contrast to their dwarf shoot phenotype (Yaxley et al, 2001). It was therefore expected that another GA 3-oxidase must carry out substantial 3-oxidation in the roots (Yaxley et al, 2001). Indeed, another pea GA 3-oxidase gene, PsGA3ox2 (Supplemental Fig.…”

Section: La and Cry Encode Della Proteinsmentioning

confidence: 99%

“…The na-1 mutant has been crucial for establishing a role for GAs in root development (Yaxley et al, 2001). This mutant has an extremely short shoot phenotype, termed nana, and roots that are shorter, thicker, and less ramified than those of wild-type plants (Yaxley et al, 2001). We found (Fig.…”

Section: La and Cry Encode Della Proteinsmentioning

confidence: 99%

“…For example, the application of bioactive GA to roots treated with the growth inhibitor ancymidol completely restored growth to that of the untreated plants (Tanimoto, 1991). Yaxley et al (2001) established the importance of GAs for root growth in peas (Pisum sativum) by using a variety of GA-deficient mutant plants. In the na-1 mutant, for example, root GA 1 levels, and root elongation, were significantly reduced compared with wild-type plants, and when the GA 1 content was restored to wild-type levels, so too was root elongation.…”

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confidence: 99%

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The Pea DELLA Proteins LA and CRY Are Important Regulators of Gibberellin Synthesis and Root Growth

et al. 2008

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The theory that bioactive gibberellins (GAs) act as inhibitors of inhibitors of plant growth was based originally on the slender pea (Pisum sativum) mutant (genotype la cry-s), but the molecular nature of this mutant has remained obscure. Here we show that the genes LA and CRY encode DELLA proteins, previously characterized in other species (Arabidopsis [Arabidopsis thaliana] and several grasses) as repressors of growth, which are destabilized by GAs. Mutations la and cry-s encode nonfunctional proteins, accounting for the fact that la cry-s plants are extremely elongated, or slender. We use the la and cry-s mutations to show that in roots, DELLA proteins effectively promote the expression of GA synthesis genes, as well as inhibit elongation. We show also that one of the DELLAregulated genes is a second member of the pea GA 3-oxidase family, and that this gene appears to play a major role in pea roots.It is well known that primary root growth is strongly influenced by the plant hormone GA (Davies, 2004). For example, the application of bioactive GA to roots treated with the growth inhibitor ancymidol completely restored growth to that of the untreated plants (Tanimoto, 1991). Yaxley et al. (2001) established the importance of GAs for root growth in peas (Pisum sativum) by using a variety of GA-deficient mutant plants. In the na-1 mutant, for example, root GA 1 levels, and root elongation, were significantly reduced compared with wild-type plants, and when the GA 1 content was restored to wild-type levels, so too was root elongation.The GAs act by destabilizing the growth inhibitory DELLA proteins (Peng et al., 1997;Harberd et al., 1998;Silverstone et al., 2001;Alvey and Harberd, 2005). In other words, GA acts as an ''inhibitor of an inhibitor '' (Harberd et al., 1998). Interestingly, there is also evidence that DELLA proteins promote the biosynthesis of active GAs. For example, in the Arabidopsis (Arabidopsis thaliana) DELLA mutant rga, the expression of the biosynthesis gene GA4 is reduced, indicating that high DELLA protein levels are associated with an up-regulation of GA synthesis genes (Silverstone et al., 2001 (Silverstone et al., 1998;Gubler et al., 2002). However, the available evidence indicates greater redundancy in dicots compared with monocots (Ikeda et al., 2001;Thomas and Hedden, 2006). There have been five DELLA genes isolated from Arabidopsis (GAI, RGA, RGL1, RGL2, and RGL3), yet only one in rice (SLR1), barley (SLN1), and maize (Zea mays; D8; Peng et al., 1997Peng et al., , 1999Silverstone et al., 1998;Ikeda et al., 2001;Chandler et al., 2002;Gubler et al., 2002), with the possibility of another DELLA gene in maize (D9; accession no. ABI84225). It should be noted, however, that DELLAs have been studied in fewer dicot model species than in monocot species. To date, DELLA-encoding genes from pea have not been reported, even though observations on the slender phenotype of pea triggered the early suggestion that GA acts an inhibitor of an inhibitor (Brian, 1957). The elongated slender phenotype, con...

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“…PsKO1 is expressed in the roots (Fig. 7), and the roots of lh-2 mutant seedlings have decreased tap root length (Batge et al, 1999;Yaxley et al, 2001) and lateral root length (Yaxley et al, 2001), coinciding with reduced GA 1 and GA 19 levels in the root (Yaxley et al, 2001). PsKO1 is also expressed in the pod (Fig.…”

Section: The Pea Gene Lh Encodes Psko1mentioning

confidence: 99%

The Pea Gene LH Encodes ent-Kaurene Oxidase

et al. 2004

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The pea (Pisum sativum) homolog, PsKO1, of the Arabidopsis GA3 gene was isolated. It codes for a cytochrome P450 from the CYP701A subfamily and has ent-kaurene oxidase (KO) activity, catalyzing the three step oxidation of ent-kaurene to ent-kaurenoic acid in the gibberellin (GA) biosynthetic pathway when expressed in yeast (Saccharomyces cerevisiae). PsKO1 is encoded by the LH gene because in three independent mutant alleles, lh-1, lh-2, and lh-3, PsKO1 has altered sequence, and the lh-1 allele, when expressed in yeast, failed to metabolize ent-kaurene. The lh mutants of pea are GA deficient and have reduced internode elongation and root growth. One mutant (lh-2) also causes a large increase in seed abortion. PsKO1 (LH) is expressed in all tissues examined, including stems, roots, and seeds, and appears to be a single-copy gene. Differences in sensitivity to the GA synthesis inhibitor, paclobutrazol, between the mutants appear to result from the distinct nature of the genetic lesions. These differences may also explain the tissue-specific differences between the mutants.

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Gibberellin Biosynthesis Mutations and Root Development in Pea

Cited by 129 publications

References 27 publications

Possible Involvement of Leaf Gibberellins in the Clock-Controlled Expression of XSP30, a Gene Encoding a Xylem Sap Lectin, in Cucumber Roots

Possible Involvement of Leaf Gibberellins in the Clock-Controlled Expression of XSP30, a Gene Encoding a Xylem Sap Lectin, in Cucumber Roots

The Pea DELLA Proteins LA and CRY Are Important Regulators of Gibberellin Synthesis and Root Growth

The Pea Gene LH Encodes ent-Kaurene Oxidase

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