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R Bottini

Publications and source records attributed to R Bottini.

8 recordsLinked to original sources
PubMed2001

Azospirillum spp. metabolize [17,17-2H2]gibberellin A20 to [17,17-2H2]gibberellin A1 in vivo in dy rice mutant seedlings.

Azospirillum spp. are endophytic bacteria with beneficial effects on cereals--effects partially attributed to gibberellin production by the microorganisms. Azospirillum lipoferum and Azospirillum brasilense inoculated to rice dy mutant reversed dwarfism in seedlings incubated with [17,17-2H2]GA20 with formation of [17,17-2H2]GA1, showing the in vivo capacity to perform the 3beta-hydroxylation. When prohexadione-Ca, an inhibitor of late steps in gibberellin biosynthesis, was added to the culture medium, no complementation was observed and no [17,17-2H2]GA1 was produced. The latter suggests that the bacterial operating enzyme may be a 2-oxoglutarate-dependent dioxygenase, similar to those of plants.

Azospirillum↗
PubMed2001

Azospirillum brasilense and Azospirillum lipoferum hydrolyze conjugates of GA20 and metabolize the resultant aglycones to GA1 in seedlings of rice dwarf mutants.

Azospirillum species are plant growth-promotive bacteria whose beneficial effects have been postulated to be partially due to production of phytohormones, including gibberellins (GAs). In this work, Azospirillum brasilense strain Cd and Azospirillum lipoferum strain USA 5b promoted sheath elongation growth of two single gene GA-deficient dwarf rice (Oryza sativa) mutants, dy and dx, when the inoculated seedlings were supplied with [17,17-2H2]GA20-glucosyl ester or [17,17- 2H2]GA20-glucosyl ether. Results of capillary gas chromatography-mass spectrometry analysis show that this growth was due primarily to release of the aglycone [17,17-2H2]GA20 and its subsequent 3beta-hydroxylation to [17,17-2H2]GA1 by the microorganism for the dy mutant, and by both the rice plant and microorganism for the dx mutant.

Azospirillum↗
PubMed2001

Morphological changes in garlic (Allium sativum L.) microbulblets during dormancy and sprouting as related to peroxidase activity and gibberellin A3 content.

The aim of this work was to study the physiological mechanisms of dormancy and sprouting during post-harvest of garlic (Allium sativum L.) microbulblets produced by meristem culture of garlic seed cloves. The morphological changes occurring in garlic microbulblets were assessed from harvest till sprouting in relation with peroxidase activity and levels of gibberellins. Also the effect of a cold treatment (30 days at 4 degrees C) given 30 days after harvest was studied. The results showed that during the state of dormancy in garlic microbulblets formation of the leaf primordia and vascular differentiation of the storage leaf occurred, while increases of peroxidase activity and low levels of GA3 (the only active gibberellin identified) were found. At the end of dormancy the sprouting channel was formed, vascular differentiation established, and peaks of soluble peroxidase activity as well as of GA3 were observed. At day 90 post-harvest, garlic microbulblets showed physiologically mature and able to sprout. Further on, bud expansion and decrease of GA3 levels characterized sprouting of the microbulblets. The cold treatment enhanced GA3 levels and anticipated the sprouting process.

Cell Differentiation↗
PubMed1990

Dormancy in Peach (Prunus persica L.) Flower Buds : I. Floral Morphogenesis and Endogenous Gibberellins at the End of the Dormancy Period.

Flower buds of peach (Prunus persica L.) trees, cv Novedad de Cordoba (Argentina), were collected near the end of the dormant period and immediately before anthesis. After removal of scale leaves, morphological observations of representative buds, made on transverse and longitudinal microtome sections, showed that all verticils making up the flower are present in an undifferentiated form during the dormant period (June). Flower buds collected at the end of dormant period (August) showed additional growth and differentiation, at which time formation of two ovules was beginning in the unicarpelar gynoecium. Dehiscence of anthers had not yet occurred 10 days before full bloom, and the ovules were still developing. Free endogenous gibberellin (GA)-like substances were quantified by bioassay (Tan-ginbozu dwarf rice microdrop) after SiO(2) partition column chromatography, reversed phase C18-high performance liquid chromatography, and finally Nucleosil [N(CH(3))(2)]high performance liquid chromatography. Bioactive fractions were then subjected to capillary gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM). Gibberellins A(1), A(3), and A(8) were tentatively identified in peach flower buds using GC-SIM and Kovat's retention indices, and relative amounts approximated by GC-SIM (2:8:6 for GA(1), GA(3), and GA(8), respectively). The highest concentration (330 nanograms per gram dry weight) of free GA(1)/GA(3) was found in dormant buds (June) and diminished thereafter. The concentration free of GA(1)/GA(3) did not increase immediately prior to bud break. However, high GA(1)/GA(3) concentrations occurred during stages where rate of growth and cellular differentiation of (mainly fertile) verticils can be influenced.

Journal Article↗
PubMed1989

Identification of Gibberellins A(1), A(3), and Iso-A(3) in Cultures of Azospirillum lipoferum.

Gibberellins A(1), A(3), and iso-A(3) were identified from aseptic cultures of Azospirillum lipoferum strain op 33 by capillary gas chromatography-mass spectrometry (GC-MS) and GC-MS-selected ion monitoring. There were 20 to 40 picograms (in GA(3) equivalents, estimated from bioassay) of gibberellins A(1) and A(3) per milliliter of cell culture (containing 10(9) cells).

Journal Article↗
PubMed1987

Metabolism of [H]Gibberellin A(5) by Immature Seeds of Apricot (Prunus armeniaca L.).

Immature seeds of apricot (Prunus armeniaca L.) were fed the native gibberellin A(5) (GA(5)) as 1- and 1,2-[(3)H]GA(5) (5.3 Curies per millimole to 16 milliCuries per millimole) at doses (42 nanograms to 10.6 micrograms per seed) 2 to 530 times the expected endogenous level. After 4 days of incubation, seeds were extracted and free [(3)H]GA-like metabolites were separated from the highly H(2)O-soluble [(3)H]metabolites. For high specific activity feeds the retention times (Rts) of radioactive peaks were compared with Rts of authentic GAs on sequential gradient-eluted --> isocratic eluted reversed-phase C(18) high performance liquid chromatography (HPLC) -radiocounting (RC). From high substrate feeds (530 and 230 x expected endogenous levels) HPLC-RC peak groupings were subjected to capillary gas chromatography-selected ion monitoring (GC-SIM), usually six characteristic ions. The major free GA metabolites of [(3)H] GA(5) were identified as GA(1), GA(3), and GA(6) by GC-SIM. The major highly water soluble metabolite of [(3)H]GA(5) at all levels of substrate GA(5) had chromatographic characteristics similar to authentic GA(1)-glucosyl ester. Expressed as a percentage of recovered radioactivity, low substrate [(3)H]GA(5) feeds (2 x expected endogenous level) yielded a broad spectrum of metabolites eluting at the Rts where GA(1), GA(3), GA(5) methyl ester, GA(6), GA(22), GA(29) (17, 14, 1.6, 7, 1.1, 0.5%, respectively) and GA glucosyl conjugates of GA(1), GA(3), GA(5), and GA(8) (33, 11, 1, 0.1%, respectively) elute. Metabolites were also present at Rts where GA glucosyl conjugates of GA(6) and GA(29) would be expected to elute (8 and 0.1%, respectively). Only 5% of the radioactivity remained as GA(5). Increasing substrate GA(5) levels increased the proportion of metabolites with HPLC Rts similar to GA(1), GA(6), and especially GA(1) glucosyl ester, primarily at the expense of metabolites with HPLC Rts similar to GA(3), GA(3)-glucosyl ester, and a postulated conjugate of GA(6). There was evidence that high doses of substrate GA(5) induced new metabolites which often, but not always, differed from GA(1), GA(3), and GA(6) in HPLC Rt. These same metabolites, when analyzed by GC-SIM yielded m/e ions the same as the M(+) and other characteristic m/e ions of the above GAs, albeit at differing GC Rt and relative intensities.

Journal Article↗
PubMed1985

Identification of Gibberellins A(1), A(5), A(29), and A(32) from Immature Seeds of Apricot (Prunus armeniaca L.).

Gibberellins (GAs) A(1), A(5), and A(29) were identified, and also GA(32) was confirmed, as endogenous GAs of immature seeds (3-4 weeks after anthesis, 0.25-0.5 gram fresh weight) of apricot (Prunus armeniaca L.) based on capillary gas chromatography (GC), retention time (Rt), and selected ion monitoring (SIM), in comparison with authentic standards. Fractions subjected to GC-SIM were purified and separated using sequential solvent partitioning --> paper chromatography --> reverse phase C(18) high performance liquid chromatography (HPLC) --> bioassay on dwarf rice cv Tan-ginbozu. Two other peaks of free GA-like bioactivity (microdrop and immersion dwarf rice assays) were eluted from C(18) HPLC at Rts where GA(4/7) and GA(8) (or other GAs with similar structures) would elute. Also, three unidentified GA glucoside-like compounds (based on bioactivity on the immersion assay, and no bioactivity on the microdrop assay) were noted. There were very high amounts of GA(32) (112 ng of GA(3) equivalents per gram fresh weight), and minor amounts (0.5 ng of GA(3) equivalents) for each of GA(1) and GA(5), respectively, based on the microdrop assay.

Journal Article↗