Increased phloem transport of S-methylmethionine positively affects sulfur and nitrogen metabolism and seed development in pea plants.

Seeds of grain legumes are important energy and food sources for humans and animals. However, the yield and quality of legume seeds are limited by the amount of sulfur (S) partitioned to the seeds. The amino acid S-methylmethionine (SMM), a methionine derivative, has been proposed to be an important long-distance transport form of reduced S, and we analyzed whether SMM phloem loading and source-sink translocation are important for the metabolism and growth of pea (Pisum sativum) plants. Transgenic plants were produced in which the expression of a yeast SMM transporter, S-Methylmethionine Permease1 (MMP1, YLL061W), was targeted to the phloem and seeds. Phloem exudate analysis showed that concentrations of SMM are elevated in MMP1 plants, suggesting increased phloem loading. Furthermore, expression studies of genes involved in S transport and metabolism in source organs, as well as xylem sap analyses, support that S uptake and assimilation are positively affected in MMP1 roots. Concomitantly, nitrogen (N) assimilation in root and leaf and xylem amino acid profiles were changed, resulting in increased phloem loading of amino acids. When investigating the effects of increased S and N phloem transport on seed metabolism, we found that protein levels were improved in MMP1 seeds. In addition, changes in SMM phloem loading affected plant growth and seed number, leading to an overall increase in seed S, N, and protein content in MMP1 plants. Together, these results suggest that phloem loading and source-sink partitioning of SMM are important for plant S and N metabolism and transport as well as seed set.

Pine (Pinus radiata).

This chapter describes the transformation of Pinus radiata using organogenic cotyledon explants rather than the more common somatic embryogenesis methods for conifers. The advantages of our method are the year round availability of seed and that over 80% of genotypes can be easily regenerated from the mature cotyledon explants. The transformation efficiency (i.e., the number of transformed shoots regenerated from excised cotyledons) is 1.7% and, as with other Agrobacterium tumefaciens transformation methods, the majority of transgene integrations are single copy. Critical factors for success are survival of the cotyledons, Agrobacterium strain, and selection pressure after cocultivation.

Peas (Pisum sativum L.).

In this chapter we describe a robust method for transformation of peas that has been successfully used in our laboratory since 1992. Using immature pea seed collected from field- or greenhouse-grown plants, we have produced transgenic lines for over 30 genotypes including named pea cultivars and advanced breeding lines. This method uses immature cotyledons as the explant, and the transformation efficiency is in the range 0.2 to 13.5% of cotyledons producing at least one independently transformed line. Agrobacterium tumefaciens strains AGL1 and KYRT1 are the most successful in our procedure, and kanamycin, phosphinothricin, and hygromycin are reliable selectable markers. Potentially useful genes have been introduced for pest and disease resistance, altering quality traits, and investigating metabolic pathways and are being studied in transgenic pea lines.

Increases in plasma lycopene concentration after consumption of tomatoes cooked with olive oil.

Lycopene is the main carotenoid in tomatoes and it has been hypothesised to be responsible for reducing the risk of some cancers and heart disease. The cooking of tomatoes with olive oil is a characteristic combination in the Southern Mediterranean diet. Previous studies have shown that the absorption of lycopene is greater from processed tomatoes than fresh tomatoes, since the processing breaks down the tomato cell matrix and makes the lycopene more available. The aim of the present study was to determine whether consumption of diced tomatoes cooked with olive oil resulted in higher plasma lycopene concentrations than consumption of diced tomatoes cooked without olive oil. Plasma lycopene concentrations were measured after 5 days on a low lycopene diet and again after a five-day dietary intervention, in healthy subjects, who consumed one meal per day of tomatoes (470 g) cooked with or without extra virgin olive oil (25 ml olive oil). There was an 82% increase in plasma trans-lycopene (P< 0.001) and a 40% in cis-lycopene (P = 0.002) concentrations in the 11 subjects who consumed tomatoes cooked in olive oil. There was no significant change in trans-lycopene (P = 0.684) and a 15% increase in cis-lycopene (P = 0.007) concentrations in 12 subjects consuming tomatoes cooked without olive oil. We conclude that the addition of olive oil to diced tomatoes during cooking greatly increases the absorption of lycopene. The results highlight the importance of cuisine (i.e how a food is prepared and consumed) in determining the bioavailability of dietary carotenoids such as lycopene.