The Effect of Ultraviolet Radiation and Sucrose on IAA Levels in Spirodela oligorhiza

Witztum, A.; Keren, O.; Even‐Chen, Zeev

doi:10.1093/oxfordjournals.aob.a085493

Cited by 20 publications

(4 citation statements)

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Section: Discussionmentioning

confidence: 81%

“…Whether the differences among plant types are due to developmental stage or to the state of growth of the plants remains to be determined. High auxin levels have previously been reported for members of the Lemnacea (26,29).While other mutant plants with increased levels of IAA have been isolated (14,16,28), the levels of IAA reported are much lower than that found in 45 d cultures of jsR,. High accumulation variants are rare and, in some cases, the analytical information provided was limited.…”

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confidence: 86%

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Levels of Indole-3-Acetic Acid in Lemna gibba G-3 and in a Large Lemna Mutant Regenerated from Tissue Culture

Slovin¹,

Cohen²

1988

Plant Physiol.

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Large changes in indole-3-acetic acid (IAA) levels occur during growth of Lemna gibba G-3 in sterile culture. The levels of IAA were measured in plants during a 45 day growth cycle using HPLC and isotope dilution analysis followed by selected ion current monitoring GC-MS analysis with 13C6-IAA as the internal standard. Even though the rate of plant growth remained constant over the entire growth period, IAA levels ranged from a high of 222 to a low of 6 nanograms per gram fresh weight. A Lemna mutant (jsR,) which has a giant phenotype was obtained by regeneration from primary callus cultures. Microspectrofluorometry of diamidino-2-phenylindole stained cells showed that jsR, has the same amount of DNA per nucleus as the parent line (PL). All jsR, cell types measured are about 1.5 times larger than in PL. The endogenous levels of IAA per gram fresh weight were higher in jsR, at several stages of the plant culture cycle as compared to PL. This difference ranged from 1.2 to over 100 times as much. While PL showed only one high peak at day 9, jsR, had IAA levels of 480 and 680 nanograms per gram fresh weight at days 9 and 45, respectively. Throughout the midculture stage of the growth cycle (20-28 days) both jsR, and PL had IAA levels in the range of 9 to 14 nanograms per gram fresh weight. In contrast to PL, at day 45, jsR, had no detectable ester or amide conjugates of IAA. These changes in IAA levels were determined in sterile plant cultures and thus cannot be attributed to bacterial or fungal activity. sist of cloned vegetative plants. Our cultures of Lemna gibba G-3 increase in frond2 number and fresh weight at a logrithmic rate throughout a 45 d culture cycle. In this report we show that, during the culture cycle, endogenous IAA levels vary from only a few ng/g FW3 to several hundred ng/g FW.Size variation in selected varieties of higher plants has been attributed to a variety of genetic determinants such as ploidy level (3), root physiology (20), and hormonal variations (20,22 injector was at 260°C and the oven was programmed with a 2 min isothermal hold at 140°C then increased at 5°C/min. Ultrapure He, after passage through an oxygen trap and through a molecular sieve (Linde 4A), was used as carrier gas at a flow rate of 1 ml/min.Ester and amide conjugates were determined by using selective base hydrolysis as previously described (12). Data presented are the average of four replicate experiments. RESULTSGrowth Characteristics. L. gibba G-3 is an aquatic angio §perm that grows well in sterile culture on minimal media. Under short day conditions propagation is entirely vegetative. Using E media, which consists of salts and contains 1% sucrose, flasks planted with Lemna support plant growth at a logrithmic rate for over 45 d, with no apparent lag phase or plateau (Fig. 2). Growth rate does not account for the difference in size of PL and jsR,.Lemna fronds exhibit a determinant growth characteristic. Each frond will produce approximately 15 daughter fronds and then the mother frond senesces. In our cultu...

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Section: Discussionmentioning

confidence: 81%

mentioning

confidence: 86%

Levels of Indole-3-Acetic Acid in Lemna gibba G-3 and in a Large Lemna Mutant Regenerated from Tissue Culture

Slovin¹,

Cohen²

1988

Plant Physiol.

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“…The levels of IAA in members of the Lemnacea have been described in early work by Thimann et al (29) who used bioassays to show that auxin was present in bound and free forms in Lemna minor and, in later work, by Witztum et al (30), who used a spectrofluorometric method that indicated that there was greater than 2 ug free IAA per g fresh weight of Spirodela oligorhiza. Our finding of 6.62 ng of free IAA per g fresh weight of Lemna gibba grown under conditions similar to those in the study by Witztum et al (30) suggests either that there is a significant problem with the spectrofluorometric technique that they employed, that there is dramatic species heterogeneity within this taxonomic family, or that members of this family undergo dramatic changes in their IAA and 96.5%. …”

Section: Methodsmentioning

confidence: 97%

¹³C₆-[Benzene Ring]-Indole-3-Acetic Acid

Cohen¹,

Baldi²,

Slovin³

1986

Plant Physiol.

231

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Indole-3-acetic acid (IAA) labeled with 13C in the six carbons of the benzene ring is described for use as an internal standard for quantitative mass spectral analysis of IAA by gas chromatography/selected ion mon-itoring. ['3C6jIAA was compared to the available deuterium labeled compounds and shown to offer the advantages of nonexchangeability of the isotope label, high isotopic enrichment, and chromatographic properties identical to that of the unlabeled compound. The utility of I'3C46IAA for measurement of endogenous IAA levels was demonstrated by analysis of IAA in Lemna gibba G-3.Techniques for identification and quantitative analysis of endogenous plant hormones are important for studies of the physiology and biochemistry of these regulatory messengers of higher plants. The use of combined GC-MS for both identification and quantification has proven to be the most accurate and certain method for plant hormone analysis. Even MS has its limitations and a major difficulty in the application of GC-MS to plant hormone analysis has been the limited availability of the appropriate stable isotope labeled 'heavy' internal standards.Various internal standards have been utilized for the analysis of IAA. For example, 5-methyl-IAA (26), indole-3-butyric acid (20), and indole-3-propionic acid (24) (15) synthesized two ring labeled compounds. The most effective of the two compounds described was 4,5,6,7-d4-IAA, and this internal standard has been used for a number of investigations (5, 12,13, 19,23 MATERIALS AND METHODS Apparatus. All mass spectra and GC-SIM2-MS were obtained on a Hewlett-Packard3 5992A GC-MS. The instrument was modified as follows: HPl 8740B capillary inlet system, direct capillary connection, improved ion source, Edwards E2M2 roughing pump, and a 'B' type diffusion pump. SIM analysis was done using a 4 ion program dwelling on each ion for 400 ms. For methyl esters using ['3C6JIAA as the internal standard, the ions at m/z 130, 136, 189, and 195 were monitored. The GC-MS was operated for SIM using underresolved peaks ('fat peak monitoring') and a window size of 0.30 atomic mass unit. All work was performed on WCOT fused silica columns. Two types were used: a 12 meter cross-linked methyl silicone column with a film thickness of 0.33 ,um and an internal diameter of 0.20 mm (Hewlett-Packard 19091-60312) and an 11 meter midpolarity bonded phase column of CP Sil 19 CB with a film thickness of 0.18 Am and an internal diameter of 0.31 mm (Chrompack 7732-214620). The injector was at 250°C and He at 1 ml/min was the carrier gas. With the Hewlett-Packard column the oven was at 1 60°C for 2 min followed by temperature programming at 10°C/min. The Chrompack column was held at 140°C for 2 min followed by temperature programming at 5°C/ min. Injections were made in the splitless mode with the column vented for the first 1.5 min.Fourier transform IR spectra were obtained in KBr on a Nicolet 60SX instrument.Reagents. Stable isotope labeled compounds were obtained as follows: Indole-3-acetic-2,2-d2 acid (MD-170...

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“…IAA absorbs in the UV-B region and can be converted in vitro and in vivo to different photo-oxidation products . Increased UV-B radiation has been shown to reduce the concentration of auxin in fronds of Spirodella oligorhiza (Wiztum et al, 1978) and in the hypocotyls of sunflower seedlings .…”

Section: Changes In Plant Growth and Development With Uv-b Radiamentioning

confidence: 99%

Ultraviolet-B Radiation and Photosynthesis

Teramura

Ziska

Photosynthesis and the Environment

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The Effect of Ultraviolet Radiation and Sucrose on IAA Levels in Spirodela oligorhiza

Cited by 20 publications

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Levels of Indole-3-Acetic Acid in Lemna gibba G-3 and in a Large Lemna Mutant Regenerated from Tissue Culture

Levels of Indole-3-Acetic Acid in Lemna gibba G-3 and in a Large Lemna Mutant Regenerated from Tissue Culture

¹³C₆-[Benzene Ring]-Indole-3-Acetic Acid

Ultraviolet-B Radiation and Photosynthesis

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The Effect of Ultraviolet Radiation and Sucrose on IAA Levels in Spirodela oligorhiza

Cited by 20 publications

References 0 publications

Levels of Indole-3-Acetic Acid in Lemna gibba G-3 and in a Large Lemna Mutant Regenerated from Tissue Culture

Levels of Indole-3-Acetic Acid in Lemna gibba G-3 and in a Large Lemna Mutant Regenerated from Tissue Culture

13C6-[Benzene Ring]-Indole-3-Acetic Acid

Ultraviolet-B Radiation and Photosynthesis

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¹³C₆-[Benzene Ring]-Indole-3-Acetic Acid