Auxin regulation of gibberellin biosynthesis in the roots of pea (Pisum sativum)

Weston, Diana E.; Reid, James B.; Ross, John J.

doi:10.1071/fp08301

Cited by 26 publications

(23 citation statements)

References 25 publications

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“…Interestingly, even though gibberellins are implicated in a wide range of processes critical for plant yield, including root growth, seed development, and nodulation (e.g., Ferguson et al 2011;Ross et al 2011), Mendel's le-1 mutation has been used in agriculture for many centuries. This appears to have been possible because the LE gene is only one of a family of GA 3-oxidase genes, with at least one other member having greater expression in the roots and seeds and compensating for any loss of 3-oxidase activity in le-1 plants (Weston et al 2009). …”

Section: Stem Lengthmentioning

confidence: 99%

Mendel’s Genes: Toward a Full Molecular Characterization

Reid

Ross

2011

Genetics

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The discipline of classical genetics is founded on the hereditary behavior of the seven genes studied by Gregor Mendel. The advent of molecular techniques has unveiled much about the identity of these genes. To date, four genes have been sequenced: A (flower color), LE (stem length), I (cotyledon color), and R (seed shape). Two of the other three genes, GP (pod color) and FA (fasciation), are amenable to candidate gene approaches on the basis of their function, linkage relationships, and synteny between the pea and Medicago genomes. However, even the gene (locus) identity is not known for certain for the seventh character, the pod form, although it is probably V. While the nature of the mutations used by Mendel cannot be determined with certainty, on the basis of the varieties available in Europe in the 1850s, we can speculate on their nature. It turns out that these mutations are attributable to a range of causes-from simple base substitutions and changes to splice sites to the insertion of a transposon-like element. These findings provide a fascinating connection between Mendelian genetics and molecular biology that can be used very effectively in teaching new generations of geneticists. Mendel's characters also provide novel insights into the nature of the genes responsible for characteristics of agronomic and consumer importance.

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Section: Stem Lengthmentioning

confidence: 99%

Mendel’s Genes: Toward a Full Molecular Characterization

Reid

Ross

2011

Genetics

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“…However, in roots the auxin action inhibitor PCIB caused significantly less inhibition of elongation in la cry-s plants than in phenotypically wild type plants, although this does not distinguish between the effect of auxin on GA synthesis or an effect on the GA response pathway. 15 Likewise, decapitation did not reduce the elongation of young expanding internodes in the DELLA-deficient pea mutant la cry-s (at this stage of development) as it does in plants with a wild-type phenotype (Table 1, p < 0.01). This presumably occurs since GA 1 levels and hence auxin levels are not important for elongation in the absence of the growth-inhibiting DELLA proteins.…”

Section: Ecological Implicationsmentioning

confidence: 98%

“…For example, with respect to GA 1 synthesis, the shoot-expressed GA20ox1 gene seems to be only marginally upregulated in pea shoots, with the main effect attributable to the upregulation of Mendel's GA 3-oxidase gene, LE. 12,15 However, in tobacco GA 20-oxidation is strongly upregulated. 14 The reason for this difference is not clear, although at least two hypotheses can be suggested.…”

Section: Generality Of the Auxin-ga Interactionmentioning

confidence: 99%

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Auxin acts independently of DELLA proteins in regulating gibberellin levels

Reid

Davidson

Ross

2011

Plant Signaling & Behavior

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Shoot elongation is a vital process for plant development and productivity, in both ecological and economic contexts. Auxin and bioactive gibberellins (GAs), such as GA 1 , play critical roles in the control of elongation, 1-3 along with environmental and endogenous factors, including other hormones such as the brassinosteroids.4,5 The effect of auxins, such as indole-3-acetic acid (IAA), is at least in part mediated by its effect on GA metabolism, 6 since auxin upregulates biosynthesis genes such as GA 3-oxidase and GA 20-oxidase and downregulates GA catabolism genes such as GA 2-oxidases, leading to elevated levels of bioactive GA 1 . 7 In our recent paper, 1 we have provided evidence that this action of IAA is largely independent of DELLA proteins, the negative regulators of GA action, 8,9 since the auxin effects are still present in the DELLA-deficient la cry-s genotype of pea. This was a crucial issue to resolve, since like auxin, the DELLAs also promote GA 1 synthesis and inhibit its deactivation. DELLAs are deactivated by GA, and thereby mediate a feedback system by which bioactive GA regulates its own level.10 However, our recent results, 1 in themselves, do not show the generality of the auxin-GA relationship across species and phylogenetic groups or across different tissue types and responses. Further, they do not touch on the ecological benefits of the auxin-GA interaction. These issues are discussed below as well as the need for the development of suitable experimental systems to allow this process to be examined.

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“…GA19, GA20, GA1, GA29 and GA8 have also been found in P. sativum roots via Gas Chromatography/Mass Spectrometry using Selected Ion Monitoring (GC/MS-SIM) (Weston et al, 2009).…”

Section: A Possible Role For Ga In Nodulationmentioning

confidence: 99%

Molecular genetic and biochemical analysis of gibberellic acid involvement in the stages of soybean (Glycine max L.) nodule development

Potten¹

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This thesis aimed to characterise four genes identified to be involved in early nodulation in Glycine max (soybean). The first gene studied was a GmTIR-NBS-LRR gene, a Toll/Interleukin 1 receptor -Nucleotide Binding Site -Leucine-Rich Repeat (TIR-NBS-LRR) suspected of being involved in host specificity in regards to rhizobia. Over-expression, silencing and histochemical promoter studies of this gene saw no phenotypic changes. This is due to the previously unknown existence of a transcript variant (TV) of the gene as well as the likely existence of alternative promoter(s) (AP). Future characterisation work will focus on understanding and identifying the TVs and possible APs of GmTIR-NBS-LRR.The remaining three early nodulation genes are involved in GA biosynthesis, a plant hormone whose role in nodulation is still unclear. The genes GmGA20ox a, GmGA2ox and GmGA3ox 1a were analysed through silencing and histochemical promoter studies, over-expression and phytogenic analysis and histochemical promoter studies, respectably. Additionally, measurement of endogenous GAs in G. max roots which had yet to be reported was carried out.No phenotypic changes were observed following either silencing or over-expression for any of the GA biosynthesis genes. The histochemical promoter studies of GmGA20ox a highlighted likely role in facilitating infection thread formation and early nodule development in the cortical cells. GmGA3ox 1a appeared to be more general, but still NF dependent in its expression, through its widespread presence in the phloem during early nodulation.Successful measurement of endogenous GA has shown that independent of nodulation, GA3 is the more abundant bioactive GA in soybean compared to GA1. This differs from Pisum sativum (pea) roots where GA3 was not detected and GA1 is most abundant.The recent availability of G. max mutants of many of these genes through Soybase (http://soybase.org), coupled with the new method for measuring endogenous GA in G. max roots, opens up many pathways for further effective characterisation of these nodulation specific genes and thus, a better understanding of nodulation as a whole.

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Auxin regulation of gibberellin biosynthesis in the roots of pea (Pisum sativum)

Cited by 26 publications

References 25 publications

Mendel’s Genes: Toward a Full Molecular Characterization

Mendel’s Genes: Toward a Full Molecular Characterization

Auxin acts independently of DELLA proteins in regulating gibberellin levels

Molecular genetic and biochemical analysis of gibberellic acid involvement in the stages of soybean (Glycine max L.) nodule development

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