Plastid Pigment Changes in the Early Seedling Leaves of Zea Mays L

Accumulation of carotenoid pigments in the shoot apex of etiolated pea (Pisum sativum cv. Alaska) seedlings is completely prevented by ethylene. Under certain conditions carotenoid synthesis is normally controlled by endogenously produced ethylene. The gas completely inhibits carotenoid synthesis induced either by continuous white light or brief illumination with red light, but only partially inhibits light-induced chlorophyll formation. Far red illumination followed by red illumination reverses the action of red light on carotenoid synthesis. Red light-induced carotenogenesis is partly or wholly caused by phytochrome-mediated inhibition of ethylene biosynthesis.

Section: Methodsmentioning

confidence: 99%

Involvement of Ethylene in Phytochrome-mediated Carotenoid Synthesis

Kang

Burg

1972

“…Although there were some disparities in the responses reported, studies on leaves, seedlings, and cotyledons showed some indications of sunlight-stimulated synthesis of cyclic carotenoids (5,6,8,16,19). Conversely, red blush grapefruits placed under reduced light ("shade") consistently had slightly higher lycopene concentrations than those exposed to sunlight (12,13).…”

Section: Methodsmentioning

confidence: 99%

Comparative Study of the Carotenoid Composition of the Seeds of Ripening Momordica charantia and Tomatoes

Rodriguez¹,

Lee²,

Chichester³

1975

The total carotenoid concentration of the seeds of Momordica charantia rose about 100-fold from the immature to the ripe stage. The massive increase was almost exclusively attributable to lycopene, which accounted for 96% of the carotenoids of the ripe seeds. The carotenoid pattern of the seed was found to be drastically different from that of the pericarp. The seed, which contained fewer carotenoids, had a total concentration 12 times greater than that Ripe cherry tomatoes, Lycopersicon esculentum var. Cerasiforme (Dun.) A. Gray, were purchased from a local fruit market. The cherry variety was used because the seeds were easier to separate. The seeds from 900 g of fruits were separated from the pericarp and washed with water on a sieve to remove juice and residual pulp. The water was drained and the seeds were air dried on the sieve for a couple of hours. Four 30-g samples were taken and analyzed separately.In addition to the authentic carotenoids used for comparison in the preceding study, lycoxanthin and rubixanthin were extracted and purified from Solanum dulcamara and rose hips, respectively.Extraction and Separation of Carotenoids. The carotenoids of the seeds of both fruits were extracted and saponified in the same manner described for the pericarp (17). The saponified pigments from the ripe and partly ripe Momordica samples were separated initially on a column of alumina (activity grade III), using 1 to 5% (v/v) ethyl ether in petroleum ether as solvent. Fraction 4 was rechromatographed on a MgO-HyfloSupercel (1:2) column developed with 25% (v/v) acetone in petroleum ether, resulting in the formation of five bands (fractions 4-a to 4-e). If necessary, these bands could be purified on a silica gel plate (Quanta Gram TLC plates QIF, Quantum Industries, New Jersey) with 3%C (v/v) methanol in benzene as the developing solvent. The pigments extracted from the immature seeds separated into four bands on the alumina column. These fractions consisted of single carotenoids and thus needed no further separation. The topmost fraction of pigments from mature samples consisted of three components when rechromatographed on a silica gel plate developed with 3% (v/v) methanol in benzene. As in the previous study, the colorless eluate preceding the fluorescent phytofluene band was collected and examined for the presence of phytoene.The tomato seed carotenoids were fractionated as described for the whole fruit (15) except that lycopene was subsequently separated from the xanthophylls on an alumina column (activity grade III) developed with 1 to 5% (v/v)

“…The reversion of the mutant seedlings to the normal phenotype has been discussed in a previous paper (13 In a previous study (11) it was found that the rate of oxidation of a-ketoglutarate by a mitochondrial preparation from sweet potato roots was considerably enhanced when diphosphothiamine, diphosphopyridine nucleotide, and coenzyme A were added to a basic reaction mixture of adenylate, magnesium, and glucose in a phosphate buffer at pH 7.0. It was of interest, therefore, to examine the phosphorylative capacity of this reconstituted a-ketoglutarate oxidase.…”

Section: Discussionmentioning

confidence: 99%

“…The mitochondria 1 Received April 10, 1956. were prepared by the methods outlined in another paper (11). The final mitochondrial pellet was suspended in 10 ml of 0.5 M sucrose instead of 6 ml as used for the studies on cofactor requirements.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The Control of Plastid Pigment Formation by a Virescent Gene, Pale-Yellow-1, of maize.

Kay

Phinney

1956

Self Cite

The effects of certain environmental factors upon the phenotypic expression of a single-gene mutation, pale-yellow-1, of maize have been described (13). In brief, the observations showed that the mutant seedling is initially uniform pale-yellow in color when grown in either light or darkness. However, when exposed to light at 250 C the mutant seedlings become green in color approximately 8 days after planting. Plastid size and number, type of culture media used, length of previous exposure to light and the presence of the endosperm are not factors in this delayed appearance of pigments.This paper will present quantitative information on the pigment content and pigment changes which occur in the mutant, pale-yellow-1, of maize. In particular, an attempt will be made to establish the relationship of the mutant gene to the accumulation of specific carotenoid pigments and the chlorophylls.This will be done in order to determine the basis for the differences in color between the mutant and its normal sibling (13). In addition, it is hoped that some information about the biochemical relationship of the carotenoids to the chlorophylls will be obtained from these observations. METHODS The plants used in this study were germinated from seeds which were found to produce seedlings in a ratio of 3 normals to 1 mutant. All seedlings were grown in a constant temperature chamber at 25 -0.50 C. Light (700 ft-c) was supplied by 13 slimline fluorescent lamps labeled 45000 white. A description of the culture methods, light source and the constant temperature chamber has been reported (13 When the samples were analyzed for carotenoids, the pigments were extracted with methanol, the chlorophylls saponified and the carotenoids transferred to a mixture of ethyl ether and petroleum ether. The carotenols were chromatographically resolved into individual components on a magnesia column, while the carotenes passed through the column and were recovered as a binary mixture in the perculate. Samples analyzed for chlorophylls were extracted with methanol and the chlorophylls transferred to petroleum ether. The chlorophylls were separated from the carotenoids and resolved into chlorophyll a and chlorophyll b by chromatographing the petroleum ether solution on a starch column. Protochlorophyll a was extracted from the leaf samples and chromatographically isolated by the method of Koski and Smith (12). The amounts of chlorophyll a, chlorophyll b, protochlorophyll a, lutein, violaxanthin b, and flavoxanthin c were calculated from the absorbance, at their respective maxima, and the specific absorption coefficients given by Zscheile and Comar (17), Strain (14) and Koski and Smith (12). The amounts of beta carotene and neo-beta carotene were calculated from the absorbance of the binary solution by the method of Beadle and Zscheile (2).EXPERIMENTAL AND RESULTSPIGAIENT CONTENT OF DARK-GROWN MUTANT AND NORMAL SEEDLINGS: When grown at 250 C, 7-dayold dark-grown mutant seedlings are pale-yellow in color, while dark-grown normal seedlings are brightyell...