Tomato plants (Lycopersicon esculentum cv. OH 7814) were transformed via Agrobacterium tumefaciens with a chimeric tobacco anionic peroxidase (EC 126.96.36.199) gene joined to the cauliflower mosaic virus (CaMV) 35S promoter. Transgenic plants obtained by selection on kanamycin were found to have more than five times the total leaf peroxidase activity of control plants. Transformed tomato plants chronically wilted upon reaching sexual maturity. Two independently selected transformants were self-fertilized, and progeny were obtained that were homozygous for the foreign gene. Isoelectric focusing gels stained for peroxidase activity revealed a new tomato leaf peroxidase isoenzyme with a pI of 3.75, which is similar to that seen in Nicotiana sylvestris L. Mature tomato fruit were found to have up to 1600-fold higher peroxidase activity in transformants expressing the tobacco anionic peroxidase (TobAnPOD) than control plants. Tissue blots showed the tobacco enzyme evenly distributed throughout the tomato fruit tissue. Progeny plants possessing the tobacco peroxidase gene (now homozygous) showed stunting, and fruit size was reduced by >80%. However, fruit set was normal and the rate of ripening was not altered from control plants. Fruit from transformed plants were found to have normal pigmentation, but the soluble solids concentration was 400% higher than in control tomato fruit. This result was predicted from the peroxidase-induced water stress. Possible roles for the tobacco anionic peroxidase in growth, development, and stress resistance are discussed.
L. Mark Lagrimini, Jill Vaughn, John Finer, Karen Klotz, and Patrick Rubaihayo
Rolland Agaba, Phinehas Tukamuhabwa, Patrick Rubaihayo, Silver Tumwegamire, Andrew Ssenyonjo, Robert O.M. Mwanga, Jean Ndirigwe, and Wolfgang J. Grüneberg
The amount of genotypic and phenotypic variability that exists in a species is important for selection and initiating breeding programs. Yam bean is grown locally in tropical countries of the Americas and Asia for their tasty storage roots, which usually have low dry matter content. The crop was recently introduced in Uganda and other East and Central African countries to supplement iron (Fe) and protein content in diets. This study aimed to estimate genetic variability for root yield and quality traits among 26 yam bean accessions in Uganda. A randomized complete block design was used with two replications across two ecogeographical locations and two seasons during 2012 and 2013. Near-infrared reflectance spectroscopy (NIRS) was used to determine quality of storage root samples. Significant differences among genotypes were observed for all traits except root protein, zinc (Zn), and phosphorus contents. Genotypic variance components (
Silver Tumwegamire, Regina Kapinga, Patrick R. Rubaihayo, Don R. LaBonte, Wolfgang J. Grüneberg, Gabriela Burgos, Thomas zum Felde, Rosemary Carpio, Elke Pawelzik, and Robert O.M. Mwanga
The present study evaluated selected East African (EA) sweetpotato varieties for storage root dry matter and nutrient content and obtained information on the potential contributions of the varieties to alleviate vitamin A and mineral deficiencies. Roots obtained from 89 farmer (white- and orange-fleshed) varieties and one introduced variety (‘Resisto’) were analyzed for storage root quality using near-infrared reflectance spectroscopy technology. Location differences were only significant for starch content. The