Biosynthesis of indole-3-acetic acid in tomato shoots: Measurement, mass-spectral identification and incorporation of ?2H from ?2H2O into indole-3-acetic acid, d- and l-tryptophan, indole-3-pyruvate and tryptamine

Cooney, Terrence P.; Nonhebel, Heather M.

doi:10.1007/bf00195339

Cited by 70 publications

(51 citation statements)

References 30 publications

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“…In our experiments, we noted 18.3% 2H incorporation, but we analyzed whole axes with roots, which were shown to incorporate much less 2H into IAA than shoots (26). Tomato shoots, excised from 1-month-old plants and incubated using the same concentration of 2H20, incorporated similar levels of 2H into their IAA, 17.3% after 10 h of incubation (17). The percentage of IAA molecules incorporating different numbers of 2H atoms as related to the total labeled molecules was practically the same for all three plants, i.e.…”

Section: Discussionmentioning

confidence: 73%

“…We used 2H20 in our studies because it is both a general label for which exact knowledge of the pathway of biosynthesis is not required and it is an invasive label not likely to be excluded specifically from any cellular compartments (25). 2H20 has been used before as a nonspecific tracer of de novo synthesis of the indole ring (17,21,27,31). The incorporation of 2H from 2H20 into any of five nonexchangeable positions, 2, 4, 5, 6, and 7, of the indole ring is an indication of de novo synthesis of IAA.…”

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confidence: 99%

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Auxin Biosynthesis during Seed Germination in Phaseolus vulgaris

1992

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The relative roles of de novo biosynthesis of indoleacetic acid (IAA) and IAA conjugates stored in mature seeds (Phaseolus vulgaris L.) in supplying auxin to germinating bean seedlings were studied. Using 2H oxide and 2,4,5,6,7-[2H1L-tryptophan as tracers of IAA synthesis, we have shown that de novo biosynthesis of IAA, primarily from tryptophan, is an important source of auxin for young bean seedlings. New synthesis of IAA was detected as early as the second day of germination, at which time the seedlings began to accumulate fresh weight intensively and the total content of free IAA began to increase steadily. IAA conjugates that accumulate in large amounts in cotyledons of mature seeds may thus be considered to be only one of the possible sources of IAA required for the growth of bean seedlings.It is believed that the major source of free IAA for young seedlings are IAA conjugates stored in the seeds during their maturation. This hypothesis was developed primarily for maize in which de novo biosynthesis of IAA in the seedlings of germinating kemels is not detectable and the major source of this hormone is ester conjugates (5,19,26). Bandurski and coworkers showed that the maize seedling is essentially a closed system, in which the level of IAA is regulated by transport from the endosperm, synthesis and hydrolysis of IAA conjugates, and IAA oxidation. However, even maize includes a few cultivars that may synthesize IAA de novo during seed germination (27); thus, the general applicability of the above hypothesis remains to be tested.In legumes, the major portion of total IAA present in mature seeds is found in amide-linked conjugates (3,9,13,18). In bean (Phaseolus vulgaris L.) seeds, amide conjugates account for more than 80% of the total IAA, and they consist predominantly of a series of immunologically related IAA peptides of 3 to 25 kD (6, 7, 16). We (11) showed that amidelinked IAA conjugates declined in bean cotyledons during the first 2 d of germination; however, as germination progressed, this decline slowed down and the level of IAA conjugates remained relatively high even after almost 1 week

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Section: Discussionmentioning

confidence: 73%

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confidence: 99%

Auxin Biosynthesis during Seed Germination in Phaseolus vulgaris

1992

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“…A tryptamine pathway, similar to that found in certain fungi, exists in tomato plants (Cooney & Nonhebel, 1991). Although TNH 2 is not a major endogenous precursor of IAA in tomato shoots, it is likely that a moderate TNH 2 influx from an external origin can trigger the synthesis of IAA, leading to increased tomato plant growth.…”

Section: Plant Growth Promotion Mediated By Tryptaminementioning

confidence: 87%

Pythium oligandrum: an example of opportunistic success

et al. 2012

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Pythium oligandrum, a non-pathogenic soil-inhabiting oomycete, colonizes the root ecosystem of many crop species. Whereas most members in the genus Pythium are plant pathogens, P. oligandrum distinguishes itself from the pathogenic species by its ability to protect plants from biotic stresses in addition to promoting plant growth. The success of P. oligandrum at controlling soilborne pathogens is partly associated with direct antagonism mediated by mycoparasitism and antimicrobial compounds. Interestingly, P. oligandrum has evolved with specific mechanisms to attack its prey even when these belong to closely related species. Of particular relevance is the question of how P. oligandrum distinguishes between self-and non-self cell wall degradation during the mycoparasitic process of pathogenic oomycete species. The ability of P. oligandrum to enter and colonize the root system before rapidly degenerating is one of the most striking features that differentiate it from all other known biocontrol fungal agents. In spite of this atypical behaviour, P. oligandrum sensitizes the plant to defend itself through the production of at least two types of microbe-associated molecular patterns, including oligandrin and cell wall protein fractions, which appear to be closely involved in the early events preceding activation of the jasmonic acid-and ethylene-dependent signalling pathways and subsequent localized and systemic induced resistance. The aim of this review is to highlight the expanding knowledge of the mechanisms by which P. oligandrum provides beneficial effects to plants and to explore the potential use of this oomycete or its metabolites as new disease management strategies.

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“…Subsequently, an IPA decarboxylase converts IPA to indole-3-acetaldehyde, and indole-3-acetaldehyde is oxidized to IAA. The IPA pathway is considered a major IAA biosynthetic pathway in plants, since potential intermediates have been isolated from different species (Sheldrake, 1973;Cooney and Nonhebel, 1991;Koga, 1995;Tam and Normanly, 1998). In addition, Trp transamination activity has been found in many plants (Gamborg, 1965;Forest and Wightman, 1972;Truelsen, 1973).…”

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confidence: 99%

TheTRANSPORT INHIBITOR RESPONSE2Gene Is Required for Auxin Synthesis and Diverse Aspects of Plant Development

et al. 2009

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The plant hormone auxin plays an essential role in plant development. However, only a few auxin biosynthetic genes have been isolated and characterized. Here, we show that the TRANSPORT INHIBITOR RESPONSE2 (TIR2) gene is required for many growth processes. Our studies indicate that the tir2 mutant is hypersensitive to 5-methyl-tryptophan, an inhibitor of tryptophan synthesis. Further, treatment with the proposed auxin biosynthetic intermediate indole-3-pyruvic acid (IPA) and indole-3-acetic acid rescues the tir2 short hypocotyl phenotype, suggesting that tir2 may be affected in the IPA auxin biosynthetic pathway. Molecular characterization revealed that TIR2 is identical to the TAA1 gene encoding a tryptophan aminotransferase. We show that TIR2 is regulated by temperature and is required for temperature-dependent hypocotyl elongation. Further, we find that expression of TIR2 is induced on the lower side of a gravitropically responding root. We propose that TIR2 contributes to a positive regulatory loop required for root gravitropism.

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Biosynthesis of indole-3-acetic acid in tomato shoots: Measurement, mass-spectral identification and incorporation of ?2H from ?2H2O into indole-3-acetic acid, d- and l-tryptophan, indole-3-pyruvate and tryptamine

Cited by 70 publications

References 30 publications

Auxin Biosynthesis during Seed Germination in Phaseolus vulgaris

Auxin Biosynthesis during Seed Germination in Phaseolus vulgaris

Pythium oligandrum: an example of opportunistic success

TheTRANSPORT INHIBITOR RESPONSE2Gene Is Required for Auxin Synthesis and Diverse Aspects of Plant Development

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