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Biomedical subjects

V Raboy

Publications and source records attributed to V Raboy.

23 records · Page 2Linked to original sources
PubMed1987

The timing and rate of phytic Acid accumulation in developing soybean seeds.

The time-course of phosphorus (P) accumulation in the phytic acid fraction of developing soybean (Glycine max [L.] Merr. cv ;Williams 79') seeds as well as the relation of phytic acid P to total P content were determined. Phytic acid was detected early in embryogenesis in field-grown soybeans and accumulated in a linear fashion throughout most of seed development. Although the observed rates of accumulation ranged from 18.7 micrograms phytic acid P per seed per day in pods positioned low on the plant to 33.6 micrograms in pods positioned high on the plant, the final concentrations were the same in all cases. Nearly all of the P translocated to developing seeds was incorporated into phytic acid from the third week after flowering until physiological maturity, with the sum of nonphytic acid P compounds remaining constant. Phytic acid accumulation was also linear throughout development when soybean plants were grown in solutions having nutrient P levels that ranged from severely limiting (2.0 milligrams P per liter) to excess (50 milligrams P per liter). However, there was a pronounced effect on rate of accumulation, which ranged from 7.2 micrograms phytic acid per seed per day with limiting nutrient P to 44.7 micrograms with excess P. The change in level of phytic acid accounted for most of the alteration in total seed P that was caused by altering the P status of the plants. These results support the view that phytic acid synthesis is involved in P homeostasis of the developing soybean seed.

Journal Article↗
PubMed1985

Deletions within a defective suppressor-mutator element in maize affect the frequency and developmental timing of its excision from the bronze locus.

Six independent derivatives of the bz-m13 allele, which contains a 2.2-kilobase-pair defective Suppressor-mutator (dSpm) insertion at the bronze (bz) locus, have been isolated and analyzed. The derivatives were selected for alterations in the frequency and timing of somatic reversion; such derivatives have previously been analyzed genetically and designated "changes in state" by McClintock [McClintock, B. (1955) Carnegie Inst. Washington, Yearb. 54, 245-255]. All of the derivatives analyzed in the present study revert substantially later in development than the original insertion mutation and some show a very low frequency of reversion as well. All of the derivatives contain insertions at the same site as the parent bz-m13 allele. Deletions of 400-1300 base pairs were found in the dSpm elements in four of the six derivatives; the remaining derivatives could not be distinguished structurally from the original mutant allele. The results suggest that changes in the frequency and developmental timing of excision are attributable to alterations in the dSpm element. Furthermore, these data suggest that DNA sequences near the ends of the element are important for responding to the two transacting functions supplied by the transposition-competent Suppressor-mutator (Spm) element.

Base Sequence↗
PubMed1985

Reduced phytic Acid content does not have an adverse effect on germination of soybean seeds.

Altering the level of phytic acid phosphorus by nutritional means had no effect on the ability of soybean (Glycine max L. [Merr.], cv ;Williams 79') seeds to germinate under laboratory or greenhouse conditions. Dry matter moved out of the cotyledons at similar rates whether the germinating seeds initially contained low (0.19), medium (0.59), or high (1.00 milligram per seed) phytic acid phosphorus. Growth of roots and shoots from 3 to 9 days after planting was similar for seeds containing low and medium levels of phytic acid phosphorus. The medium level of phytic acid resembles that found in field-grown seed, so it is clear that soybean seeds normally contain a phosphorus reserve far above that needed for germination and early seedling growth.

Journal Article↗
PubMed1984

Effect of phosphorus and zinc nutrition on soybean seed phytic Acid and zinc.

The relationships between nutrient P and Zn levels and the phytic acid, P, and Zn concentrations in soybean (Glycine max L. Merr. cv ;Williams 79') seed were studied. Phytic acid increased linearly from 4.2 to 19.2 milligrams per gram as nutrient P treatment was varied from 2.0 to 50 milligrams per liter and Zn was held constant at 0.05 milligrams per liter. Leaf P concentration during seed development was found to be closely related to the concentrations of seed P and phytic acid. Leaf and seed Zn concentrations both responded positively to increasing nutrient Zn treatment. The effects of P treatment on plant and seed P and phytic acid were largely independent of the effects of Zn treatment on leaf and seed Zn. Phytic acid to Zn molar ratios ranging from 3.6 to 33.8 were observed.The effects of nutrient P treatments on the concentrations of phytic acid, seed P, and leaf P were also studied in the P-sensitive (gene np) cultivars ;Harosoy' and ;Clark' and their respective P-tolerant (gene Np) near-isogenic lines L66-704 and L63-1677. In general, the positive relationships observed among nutrient P, leaf P, seed P, and phytic acid concentrations were similar to those observed in the studies with Williams 79. When fertilized with low or moderate nutrient P (2.5 and 25.0 milligrams P per liter, respectively) no significant differences in any parameter were observed between Harosoy or Clark and their respective P-tolerant isolines. When fertilized with high nutrient P (100 milligrams P per liter), Harosoy seed had a significantly higher concentration of phytic acid (30 milligrams per gram) than did seed of its P-tolerant near-isogenic line L66-704 (24.2 milligrams per gram phytic acid), whereas no significant difference was observed between Clark and its P-tolerant near-isogenic line L63-1677 (22.8 and 21.6 milligrams per gram, respectively). Variation in the phytic acid concentrations in the mature seed of the cultivars and isolines more closely paralleled leaf P concentrations observed during seed development (49 days after flowering), than those observed at the onset of seed development (14 days after flowering). Electrophoresis and ion-exchange chromatography revealed that partially phosphorylated intermediates do not appear when phytic acid accumulation is greatly reduced by limiting the nutrient P or when accumulation is greatly accelerated by excess P.

Journal Article↗