Search Results
Abstract
Comparison of corn (Zea mays L.) kernels derived from common F2 families that were homozygous sugary (su) or homozygous for an allele of brittle (bt), termed bt-A, showed that bt-A kernels germinated nearly as well as su kernels and the time period for silking was identical in the 2 classes. The bt-A gene conditions twice the sucrose level found in su kernels.
A chimeric, willow-leaf mutation of a standard peach [Prunus persica (L.) Batsch.] phenotype was evaluated for its water use efficiency (WUE). The willow-leaf phenotype had greater WUE than its standard-leaf parent under both nonstressed and well-watered conditions, and this was supported by isotopic carbon discrimination. Under water-stress conditions, willow-leaf trees developed less water potential gradient from the roots to the leaves. The mechanisms associated with increased WUE by the willow-leaf phenotype include a reduced water potential gradient within the plant and uncoupling of the leaf from the aerial environment. Willow-leaf peach trees in seedling populations, descended from a different willow-leaf parent, also had reduced carbon isotopic discrimination than did sibling standard-leaf seedlings.
During the past several years we have been involved in identifying seasonally regulated proteins and genes from peach bark. In the present study, we describe the cloning of a protease inhibitor from a cDNA library made from winter bark tissues. A partial clone obtained from the library was extended to full length by 5' RACE. The full-length cDNA clone (final3b) is 613 bp in length, not including the poly A+ tail. The open reading frame of 237 bp codes for a 79 amino acid protease inhibitor related to the defensin family of proteins. This family of small, cysteine-rich, extracellular proteins play a role in the plantís defense response through their antifungal properties. Sequence comparison of the encoded protein using BLAST analysis revealed significant homology to protease inhibitors from Glycine max, Arabidopsis thaliana, and a defensin protein from bell pepper (Capsicum annuum). Similar to these other cysteine-rich proteins, the peach defensin contains a consensus cys arrangement and is predicted to have an amino terminal signal peptide, presumably targeting it for extracellular transport. RNA-blot analysis indicated that the gene is seasonally expressed in bark tissues of 1-year-old shoots. Transcript abundance of final3b increased in the fall, reached a peak in midwinter and then decreased. The gene was also expressed during early stages of fruit development. RNA-blot analysis of the gene in other tissues, and in response to environmental stress and wounding, is in progress.
Abstract
A single recessive gene was found to be responsible for the abnormal fruit ripening of ‘Alcobaca’ tomato (Lycopersicon esculentum Mill.). This gene causes a ripening syndrome characterized by attenuated respiratory activity and ethylene production, delayed softening of the fruit, low polygalacturonase (PG) activity, and extended shelf life. Allelism tests showed that the mutant gene of ‘Alcobaca’ is allelic to nor. It is proposed that the symbol nor A be used to refer to this mutant. The nor A allele is dominant to the nor allele.
Information about a rare allele of phosphoglucomutase (PGM) that is shared by `Braeburn' and 16% of cultivars in the New Zealand Cultivar Collection was combined with historical information about cultivar distribution to select a set of 15 cultivars for a more detailed genetic analysis of their relatedness to the key New Zealand apple (Malus domestica Borkh.) `Braeburn'. DNA from all 16 cultivars was examined by RFLP analysis using 41 probe-enzyme combinations and also by RAPD analysis with 39 selected primers. The RFLP and RAPD data excluded a proposal that `Lady Hamilton' and `Braeburn' are genetically identical. All cultivars except `Lady Hamilton' were excluded as potential parents for `Braeburn' based on incompatible RFLP banding. Assessment of genetic distances between `Braeburn' and the other 15 cultivars from RFLP and RAPD data demonstrated that `Lady Hamilton' was more closely related to `Braeburn' than all others. We conclude that there is a high likelihood that `Lady Hamilton' is one of the parents of `Braeburn'.
Abstract
A method was developed for measuring the force necessary to rupture pods of Southern peas. The combined responses of single sections from each of 10 pods was shown to be adequate to overcome natural variations. Significant differences were observed between cultivars as maturity advanced. Certain cultivars appeared to increase in toughness from the immature to the intermediate stage of maturity. Spray applications of ascorbic or abscisic acid to Southern pea plants had no apparent effect on pod rupturing force for up to 4 days after application. Pea volume and color also changed with maturity and time after spraying.
Abstract
Hybrid carrots (Daucus carota L.) are gaining a larger share of the market once devoted exclusively to open-pollinated cultivars. The carrot inbred Florida 524 has been used extensively as the male parent in experimental hybrids tested in Florida, California, Wisconsin, Texas, and Arizona. These trials have revealed that Florida 524 has good combining ability for fresh market characteristics. Florida 524 is being released jointly by the University of Florida and the U.S. Department of Agriculture.
Abstract
Flavor is an important factor in establishing consumer preference of carrots. Although harsh, strong flavor frequently occurs in available cultivars, the dominance of mild flavor in hybrids from harsh and mild parents suggests that carrot flavor can be improved rapidly when mild-flavored inbreds are available (1). Carrot inbred B2566 has been selected as a source of improved flavor and was used as a male parent in experimental hybrids tested in California, Florida, and Wisconsin. B2566 has demonstrated good combining ability for important fresh market characteristics of color, shape, and seed productivity along with desirable mild, sweet flavor and succulent texture. Because of these qualities, B2566 is being released jointly by the USDA, the Univ. of Florida, and the Univ. of California.
Abstract
Carotenes from vegetables and fruits are vitamin A precursors that contribute about half of the vitamin A in the U.S. diet (3) and two-thirds of the world diet (5). Carrots typically contain 65 to 90 ppm carotenes (1) and are estimated to be the major source of carotene for U.S. consumers (3). Few pro-vitamin A sources surpass the carotene content of typical carrots, although red palm oil can contain >825 ppm carotenes (2). Genetic selection for higher carotene levels in carrots could increase the dietary consumption of carotene and consequently vitamin A. A high carotene mass carrot population was developed for use in breeding, genetic, and biochemical studies of carrot (Fig. 1).