-cross to the multiple-flowering parent ( Table 1 ). These results would be expected if multiple flowering is conferred by a single recessive gene. This gene is hereby designated multiple flowering , symbol mf . When two flower buds were produced at the
probability of 0.491 (pooled χ 2 = 1.424). This ratio suggests that resistance is controlled by single completely dominant gene. This interpretation was confirmed by the segregation ratios in the backcross populations. The pooled BC 1 to resistant NC-76
contrast, Honda et al. (1990) present evidence that fruit color in beefsteak plant ( Perilla frutescens Britton) is controlled by a single incomplete dominant gene ( W ) that results in three phenotypic classes with white being recessive. Mature fruit
analysis of variance, was conducted with STATISTICA 5.5. The segregation data of each trait was treated as from a single locus and the genes were mapped onto the SNP and SSR markers-based genetic map ( Xu et al., 2011 ), in which linkage group nomenclature
data were subjected to χ 2 analysis to ascertain the goodness of fit between the expected and observed segregation ratios for a single dominant gene and for the phenotypic data, analysis between the SCAR markers, and the CPM resistance locus. The SCAR
Ipomoea trifida (2X = 30) is purported to be the wild Ipomoea species most closely related to the commercially grown Ipomoea batatas (sweetpotato, 6X = 90). The two species can be crossed with much difficulty, but seed occur rarely. Ipomoea trifida has been shown to possess some agronomically desirable traits that are missing in sweetpotato (e.g., sweetpotato-weevil resistance). Attempts to locate morphological markers in the diploid trifida that would serve as indicators of successful crosses with sweetpotato resulted in the identification of two traits controlled by single genes: nectary color and male sterility. Both traits require flowering to identify, and flowering is often difficult to induce in Ipomoea species. An analysis of I. trifida accessions using RAPD molecular markers was undertaken. Using a segregant population resulting from crossing a green nectary, fertile plant with a yellow nectary, male, sterile plant, RAPD analysis resulted in clear markers for both the nectary color trait and the male sterility trait. These traits now can be identified in the absence of flowering plants.
The segregation pattern of individuals originating from selfing of several monoembryonic cultivars and one polyembryonic line indicated that polyembryony in mango was of genetic nature. All the plants originating from monoembryonic cultivars bore monoembryonic fruits. A one-monoembryonic to three-polyembryonic segregation pattern was observed among individuals originated from the polyembryonic line, indicating that polyembryony in mango is under the control of a single dominant gene.
Combining the use of PCR and single-strand conformation polymorphisms (SSCP), nine sequences from the cucumber genome were successfully identified and cloned that encoded two well-conserved asparagine-proline-alanine (NPA) domain homologues to aquaporin genes. The sensitivity and detection efficiency of SSCP and restriction enzyme analysis for detecting DNA sequence variation were evaluated using similar-sized DNA fragments. The SSCP analysis was more sensitive and efficient for discriminating different clones than restriction enzyme analysis, although some sequence variation inside similar-sized DNA fragments could be identified by restriction analysis. Consideration of the results of SSCP analysis with DNA sequence information indicated that one or two base pair changes in the amplified regions could be detected. Moreover, the SSCP analysis results of genomic DNA PCR products that were amplified by degenerate primers can provide rough information about the number of member genes. If the SSCP bands of a cloned fragment (such as CRB7) did not have the corresponding bands from genomic DNA PCR products, that fragment might be a misamplified product. The PCR-based SSCP method with degenerate oligonucleotide primers should facilitate the cloning of member genes.
This paper presents the methodology for the extraction and quantitative analysis of the sugars from single kernels of maize (Zea mays L. var. saccharata Bailey). Concentrations of sorbitol, fructose, glucose, sucrose, and maltose were determined for individual kernels of sweet corn inbreds homozygous for the endosperm carbohydrate mutants sugary (su) and sugary enhancer (se) by gas chromatographic analysis. The extraction procedure was efficient and precise. Single-seed sugar analysis of kernels from the inbreds IL451b (su) and IL677a (su se) revealed that genetic differences between the inbreds was the primary source of phenotypic variation in kernel sugar content. Differences between ears of the same inbred was also a significant source of variation, whereas, in most instances, kernel-to-kernel variation on ears was not. Fifty-eight percent of the variation in the predominant corn sugar, sucrose, was attributed to genetic differences between the two inbreds. Analysis of the observed and predicted distribution in a mature-dry F2 kernel population for sucrose content indicated that single-kernel analysis can isolate the action of the se gene in segregating populations. This procedure can be used to simplify the incorporation of se into elite inbreds, map its chromosomal location, and uncover other potentially useful alleles that modify corn endosperm carbohydrate metabolism.
Fruit sweetness is the major determinant of fruit quality in melons (Cucumis melo L.) and reflects the concentration of the three major soluble sugars, sucrose, glucose, and fructose, present in the fruit flesh. Of these three sugars, sucrose is the prime factor accounting for both the genetic and the environmental variability observed in sugar content of C. melo fruit. Faqqous (subsp. melo var. flexuosus), a cultivar having a low sucrose and total sugar content, was crossed with Noy Yizre'el (subsp. melo var. reticulatus), a cultivar having a high sucrose and total sugar content. F1 plants had a sucrose content averaging slightly higher than that of the low-sucrose parent, indicating that low sucrose content is nearly completely dominant. Segregation in the F2 and backcross progenies indicated that high sucrose accumulation in melon fruit flesh is conferred by a single recessive gene herein designated suc. When the high-sucrose parent was crossed with the moderate-sucrose landrace known as Persia 202 (subsp. melo var. reticulatus), the segregation in the filial and backcross progenies suggested that additional genetic factors affect the amount of sucrose accumulation.