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Governmental recommended allowances for folic acid have increased dramatically in recent years, especially for pregnant women. Red beet is an important vegetable source of folic acid; however, little is known about the extent of variation for native folic acid content in red beet genotypes. The objective of this investigation was to evaluate variation in folic acid content (FAC) among red beet hybrids (F₁), inbred lines (IL), plant introductions (PI), and open-pollinated cultivars (OP). Eighteen genotypes, including 12 F₁ and six OP, were evaluated in field experiments during both years. Averaged over years, highly significant differences among genotypes and between F₁ and OP were detected. FAC ranged from 3.7 mg to 15.2 mg per gram dry weight. The FAC in OP was 13% higher than in F₁. Thirty genotypes, including 13 IL and 17 PI, were evaluated in greenhouse experiments during 1993 and 1994. Highly significant differences among genotypes and between IL and PI were detected. FAC varied from 1.54 mg to 11.13 mg per gram dry weight. The FAC in IL was 43% higher than in PI. These results demonstrate an approximate 10-fold variation among red beet genotypes for FAC.

The bl gene conditions a blotchy phenotype (irregular sectors of red and white root color) in table beet (Beta vulgaris ssp. vulgaris). Segregation of the bl gene was found to be consistent with a single recessive gene, however, some evidence for a departure from a single gene model was observed when blbl plants were used as females. In this report, segregation of the bl gene was examined in greater detail in 10 F₂ populations derived from crosses of red blotchy-rooted females (genotype blbl, denoted blotchy) with red-rooted males (BlBl, denoted red,), and 10 F₂ populations derived from the reciprocal cross. In blbl × BlBl crosses, the proportion of red-rooted progeny was greater than 0.75 in seven of the crosses, and was significantly greater (P = 0.005) in three crosses. A test for heterogeneity was significant, indicating that the proportion of red-rooted progeny differed significantly in these 10 crosses. In BlBl × blbl crosses, the proportion of red-rooted progeny was <0.75 in seven of the crosses and there were no significant departures from the expected 3:1 ratio in any of the individual crosses. However, a pooled estimate of the segregation ratio showed a significant (P < 0.01) departure from the 3:1 ratio (pooled estimate = 0.71). These data demonstrate transmission ratio distortion at the bl locus when blbl plants are used as both females and males in matings with wild type plants, but the degree of distortion is greater when blbl plants are used as females. Ratio distortion in such crosses may be due to a variety of factors, including increased transmission of the bl gene through female or male gametes depending on the direction of the cross, reduced fitness of maternally derived blbl progeny, epigenetic phenomena, increased fitness of paternally derived blbl progeny, or linkage of the bl gene to viability genes.

Quantitative trait loci influencing morphological traits were identified by restriction fragment length polymorphism (RFLP) analysis in a population of recombinant inbred lines (RIL) derived from a cross of the cultivated tomato (Lycopersicon esculentum) with a related wild species (L. cheesmanii). One-hundred-thirty-two polymorphic RFLP loci spaced throughout the tomato genome were scored for 97 RIL families. Morphological traits, including plant height, fresh weight, node number, first flower-bearing node, leaf length at nodes three and four, and number of branches, were measured in replicated trials during 1991, 1992, and 1993. Significant (P ≤ 0.01 level) quantitative trait locus (QTL) associations of marker loci were identified for each trait. Lower plant height, more branches, and shorter internode length were generally associated with RFLP alleles from the L. cheesmanii parent. QTL with large effects on a majority of the morphological traits measured were detected at chromosomes 2, 3, and 4. Large additive effects were measured at significant marker loci for many of the traits measured. Several marker loci exhibited significant associations with numerous morphological traits, suggesting their possible linkage to genes controlling growth and development processes in Lycopersicon.

Carotenoids have been shown to be important both nutritionally and medicinally. Carotenoid accumulation was compared during growth and storage of four carrot genotypes: YY y₁y₁y₂y₂RPRP, yyY₁ Y₁Y₂Y₂ RPRP, YY Y₁ Y₁Y₂Y₂ RPRP, and rprp. These genotypes exhibit orange, yellow, white, and pale-orange roots respectively. The orange and pale-orange genotypes are near-isogenic for rp, a gene that reduces total carotenoid content by 93%. Genotypes were grown in replicated field plots during 1996 and stored for 8 months at 4°C. Samples of root tissue were removed at 7-day intervals during vegetative growth and 4-week intervals during the postharvest period. Total carotenoid content were quantified using HPLC and spectrophotometric analyses. Increases in carotenoid content of 119% and 79% in rprp and YY y₁y₁y₂y₂RPRP and decreases of 6% and 64% in YYY₁ Y₁Y₂Y₂RPRP and yyY₁ Y₁Y₂Y₂RPRP, respectively, were measured between 62 and 100 days after planting. At 100 days after planting, YY y₁y₁y₂y₂RPRP exhibited 10-fold greater carotenoid content than rprp. Carotenoid content in yyY₁ Y₁Y₂Y₂RPRP and YY y₁y₁y₂y₂RPRP increased during the first 28 days of storage and decreased subsequently. Meanwhile, rprp began to decrease in carotenoid content at day 14 of storage. HPLC analysis at l = 445 nm revealed two large unique peaks in rprp with elution times of 27 and 28.7 minutes that were of lesser abundance in YY y₁y₁y₂y₂RPRP, suggesting that the rate of β- and α-carotene accumulation is not the only difference between YY y₁y₁y₂y₂RPRP and rprp.

The rp allele causes a significant reduction in total carotenoid pigmentation in carrot (Daucus carota L.) roots. The objective was to investigate the effect of rp on the composition, accumulation, and retention of carotenoids in two near-isolines of carrot, W266RPRP and W266rprp, during vegetative growth and postharvest storage. Field experiments were conducted during 1996 and 1997 in which roots were sampled weekly from 62 to 100 days after seed-sowing and biweekly during postharvest storage at 4 °C up to 386 days after sowing. Linear increases in total carotenoid concentration were observed for W266RPRP and W266rprp during vegetative growth. The average daily rate of increase in total carotenoid concentration in W266RPRP and in W266rprp was 12.7 and 1.3 mg·g^-1 dry weight, respectively. A linear decrease in carotenoid concentration was measured for W266RPRP but not for W266rprp during postharvest storage. At 100 days after sowing, high-performance liquid chromatography analyses showed W266rprp had 20-fold lower concentrations of a-carotene and 50-fold lower concentrations of β-carotene in root tissue compared to W266RPRP. Levels of β-carotene and lutein in the first true leaves were reduced by ≈50% in W266rprp compared to W266RPRP. Results from this investigation suggest that the rp allele affects the concentration of root and foliage carotenoids, as well as the rate of carotenoid accumulation and degradation in carrot roots. The impact of the rp allele is far greater in root tissue than in foliage, suggesting it may act as a transcription factor or structural gene affecting primarily root carotenoid biosynthesis.

A severe dwarf mutant affecting vegetative and reproductive growth arose spontaneously in our red beet (Beta vulgaris L. subsp. vulgaris) breeding nursery and was used in crosses with inbred lines to characterize its inheritance. Segregation data in backcross and F₂ generations were collected. Chi-square goodness-of-fit tests did not deviate significantly from the expected ratios for a monogenic character for each genetic background-generation combination. We propose the symbol dw to describe the genetic control of this dwarf phenotype. Greenhouse experiments were conducted to determine whether the mutant was sensitive to exogenous application of gibberellic acid (GA). GA₃ and GA_4/7 in concentrations of 0 to 1000 ppm were applied to apical meristems during flower stem development in vernalized dwarf plants. Data on flower stem length and leaf length were collected over a 6-week period during reproductive growth. Recovery of wild-type flower stem length was obtained with application of both types of GA. A 30-fold increase in flower stem length over untreated plants was accomplished by GA application. Results of these phenocopy experiments suggest the mutant gene is involved in GA synthesis.

The primary pigments in red beet are the betalains, which include the red-violet betacyanins and the yellow betaxanthins. The recent adoption of betalain pigments from red beet as an alternative to synthetic food dyes has heightened interest in genetic modification of pigment production. Dominant alleles at two tightly-linked loci (R and Y) condition production of betalain pigment in the beet plant; however, several alleles at the R locus influence pigment amount and distribution. A mutant phenotype, characterized by irregular sectors of blotchy red and white root color, arose spontaneously in the beet breeding nursery. The blotchy mutant plant was used in crosses with non-blotchy inbred lines to characterize its inheritance. Chisquare goodness-of-fi t tests of segregation data in backcross and F₂ generations for several genetic backgrounds did not deviate from the hypothesis that a single recessive gene controls the blotchy phenotype. Linkage analysis was conducted to determine if the blotchy phenotype was conditioned by a new locus or an allele at a previously described locus. Our data indicate the bl gene resides at a newly described locus linked to R and Y. Maximum likelihood estimation revealed a linkage distance between R and Y of 8.95 ± 0.49 cM. The linkage distance between R and BL was calculated at 13.99 ± 1.18 cM, and the overall linkage between Y and BL was determined to be 28.8 ± 4.2 cM. Our data suggest the RYBL genomic region plays a critical role in the genetic control of betalain biosynthesis.

Five genes, including alleles at Y, Y₁ and Y₂, and the alleles I and IO, have been implicated in conditioning carrot root color. Various combinations of these alleles can condition white, yellow, and orange xylem and phloem color in carrot roots. The recently discovered reduced pigment gene, designated rp, conditions pale orange xylem and phloem and reduces carotenoid content by 92%. To determine if the rp gene is an allele of a previously described locus or a separate locus involved in pigment biosynthesis, we crossed rprp plants to plants with yellow phloem and yellow xylem (yellow/yellow) and to plants with purple phloem and yellow xylem (purple/yellow). We generated BC₁ and F₂ progenies for evaluation of segregation data. The expected genotype of plants with yellow xylem was yyY₂Y₂RPRP and the expected genotype of plants carrying rp was yyy₂y₂rprp. More than 1900 individual plants were evaluated for root color in 38 matings. In F₂ progenies resulting from crosses of rprp × yellow/yellow, segregation data from 19 out of 20 families fit expected 12:3:1 (yellow: orange: rprp) or 15:1 (orange: non-orange) ratios (P < 0.001) indicating independence of the rp gene. In addition, 12 out of 16 families of F₂ progenies from the cross between purple/yellow plants and rprp plants fit expected 12:3:1 (yellow: orange: rprp) ratios (P < 0.001) for a 2-gene model. These data support the hypothesis that the rp gene is independent and not linked to Y and Y₂ genes.

Raw onion extract contains organosulfur compounds that prevent aggregation of platelets in human blood plasma and influence onion pungency. An increase in antiplatelet activity has the potential of reducing cardiovascular diseases. Accumulating organosulfur compounds directly influences pyruvic acid concentrations and may determine antiplatelet activity. Organosulfur compounds are volatile and may change concentration during storage. A study was conducted to evaluate antiplatelet activity, pyruvic acid content, and percent solids during cold storage. Two low-pungency lines (8155B and Exhibition) and two high-pungency (W420B and W434B) lines were grown in replicated plots at two Wisconsin locations in 1994 and 1995. Bulbs were evaluated for antiplatelet activity, percent solids, and pyruvic acid content at 40-day intervals after onion harvest. We found significant differences for antiplatelet activity and pyruvic acid content among dates of sampling and lines. Averaged over lines antiplatelet activity increased by 73% and 29% over 160 days in storage during the 1994–95 and 1995–96 storage seasons, respectively. Mean pyruvic acid concentrations increased 27% for the 1994–95 storage season and decreased 27.5% for the 1995–96 storage season. There were no significant changes for solids during storage for both years. These data indicate that antiplatelet activity increases during storage, which may be beneficial for human health. Since onions are often stored for long periods of time before sale, an increase in antiplatelet activity may be an added benefit for this crop.

Onion is a species within the Allium genus with great culinary importance. Onion extract contains organosulfur compounds that influence pungency and inhibit blood platelet aggregation. Antiplatelet activity has the potential of reducing cardiovascular disease. Onions are typically held in postharvest storage for up to 160 days, during which time volatile organosulfur compounds may be affected. A study was conducted to evaluate antiplatelet activity, pungency, and percent solids during cold storage of onions grown in replicated plots in Wisconsin and Oregon in 1994 and 1995. Organosulfur compound concentration and antiplatelet activity were also measured in progeny derived from crosses of inbred lines contrasting for pungency grown during 1995 and 1996 in Wisconsin. For the first study, bulbs were evaluated for antiplatelet activity, percent solids and pungency at 40day intervals after harvest. Significant differences were detected for these traits among years, states, dates of sampling, and lines. During the 120-day postharvest period in 1994, antiplatelet activity increased by 25% and 80% for Oregon and Wisconsin, respectively, averaged over all lines. During the same period in 1995, antiplatelet activity decreased by 35% and 4% in the two locations. For three out of four lines, antiplatelet activity was 4.6% higher for Wisconsin than Oregon. Averaged over states, antiplatelet activity was 9.7% higher in 1994 compared to 1995. Pungency was positively correlated with antiplatelet activity in Wisconsin. Broad-sense heritabilities were calculated for antiplatelet activity and organosulfur compound concentration. These data demonstrate that environmental factors influence postharvest flux of antiplatelet activity and pungency in onion.