Neily M.H.,University of Tsukuba |
Baldet P.,French National Institute for Agricultural Research |
Arfaoui I.,University of Tsukuba |
Saito T.,University of Tsukuba |
And 6 more authors.
Plant Biotechnology | Year: 2011
The aim of this research is to study the effects of salt stress during different stages of development in transgenic tomato plants overexpressing the apple spermidine synthase gene (MdSPDS1) compared to wild type (WT) plants. Under salt treatment (100 and 150 mM NaCl), tomato plants clearly displayed several stress symptoms such as impaired seedling growth, decreased chlorophyll content, reduction in fruit yield and increased electrolyte leakage (EL) in leaves. These changes were more prominent in WT plants compared to MdSPDS1 transgenic plants which accumulate significantly more polyamines, namely spermine and spermidine. The response of ascorbate peroxidase (APX) isoenzymes in tomato leaves under saline conditions was also investigated. The transcript levels of SlApx genes were significantly up regulated under 100 mM NaCl either in wild type or in transgenic plants. Under 150 mM NaCl, only transgenic plants were capable to maintain high expression of SlApx genes, whereas in WT plants the expression declined after one month treatment. As a consequence, APX activity was significantly higher in MdSPDS1 transgenic plants compared to WT under saline conditions. These results suggest that elevated APX activity might contribute largely to the protection against oxidative stress generated by NaCl treatments and thus confer salinity tolerance in tomato overexpressing MdSPDS1. © 2011 The Japanese Society for Plant Cell and Molecular Biology.
Neily M.H.,University of Tsukuba |
Matsukura C.,University of Tsukuba |
Maucourt M.,French National Institute for Agricultural Research |
Bernillon S.,French National Institute for Agricultural Research |
And 9 more authors.
Journal of Plant Physiology | Year: 2011
Polyamines are involved in crucial plant physiological events, but their roles in fruit development remain unclear. We generated transgenic tomato plants that show a 1.5- to 2-fold increase in polyamine content by over-expressing the spermidine synthase gene, which encodes a key enzyme for polyamine biosynthesis. Pericarp-columella and placental tissue from transgenic tomato fruits were subjected to 1H-nuclear magnetic resonance (NMR) for untargeted metabolic profiling and high-performance liquid chromatography-diode array detection for carotenoid profiling to determine the effects of high levels of polyamine accumulation on tomato fruit metabolism. A principal component analysis of the quantitative 1H NMR data from immature green to red ripe fruit showed a clear discrimination between developmental stages, especially during ripening. Quantification of 37 metabolites in pericarp-columella and 41 metabolites in placenta tissues revealed distinct metabolic profiles between the wild type and transgenic lines, particularly at the late ripening stages. Notably, the transgenic tomato fruits also showed an increase in carotenoid accumulation, especially in lycopene (1.3- to 2.2-fold), and increased ethylene production (1.2- to 1.6-fold) compared to wild-type fruits. Genes responsible for lycopene biosynthesis, including phytoene synthase, phytoene desaturase, and deoxy-d-xylulose 5-phosphate synthase, were significantly up-regulated in ripe transgenic fruits, whereas genes involved in lycopene degradation, including lycopene-epsilon cyclase and lycopene beta cyclase, were down-regulated in the transgenic fruits compared to the wild type. These results suggest that a high level of accumulation of polyamines in the tomato regulates the steady-state level of transcription of genes responsible for the lycopene metabolic pathway, which results in a higher accumulation of lycopene in the fruit. © 2010 Elsevier GmbH.
Nishio S.,National Institute of Fruit Science |
Yamada M.,National Institute of Fruit Science |
Sawamura Y.,National Institute of Fruit Science |
Takada N.,National Institute of Fruit Science |
Saito T.,National Institute of Fruit Science
HortScience | Year: 2011
The effectiveness of detected quantitative trait loci (QTLs) and molecular markers associated with them in tree fruit breeding is measured by the percentages of the variance associated with detected QTL effects accounting for not phenotypic variance, but genetic variance of the trait. The genetic variance can be obtained by subtracting environmental variance from the phenotypic variance. Once accurate environmental variance components are obtained for a given selection field, environmental variances under any number of replications and measurement repetitions can be estimated. We estimated environmental variance components of fruit ripening date measured by days in a Japanese pear (Pyrus pyrifolia Nakai) breeding field in the National Institute of Fruit Tree Science, Tsukuba, Ibaraki, Japan. We estimated variance among fruits within a tree (σ f 2) as 25.6, among trees within a genotype (σ t 2) as 0.2, among years (σ y 2) as 9.4, associated with genotype · year interaction (σ gy 2) as 7.9, and associated with tree · year interaction (σ ty 2) as 1.2. Because sf 2 was the largest environmental variance component, increasing the number of fruit evaluated would most effectively reduce the environmental variance, and tree replication would not because of very small σ t 2 and σ ty 2. The 95% confidence limit of a genotypic value was ± 10 days in the evaluation of five fruits on a single tree in a year and ± 7 days over 2 years. Broad-sense heritability in a family, each offspring in which was evaluated using five fruits on a single tree in a single year, was estimated at 0.83 for three full-sib families analyzed.
Hiehata N.,Fruit Tree Research Division |
Sato Y.,Fruit Tree Research Division |
Sato Y.,National Institute of Fruit Science |
Fukuda S.,Fruit Tree Research Division |
And 4 more authors.
Journal of the American Society for Horticultural Science | Year: 2012
Loquat canker (Pseudomonas syringae pv. eriobotryae) is a serious disease of loquat (Eriobotrya japonica), and no commercial cultivar in Japan is resistant to all strains of the disease. Loquat cultivar Shiromogi, which was selected from progeny seedlings of 'Mogi', is resistant to loquat canker Group C and has good fruit characteristics. This study was conducted to determine the inheritance of resistance to loquat canker Group C in 'Shiromogi'. Seedlings produced from crosses between two resistant and 13 susceptible genotypes were classified as either resistant (R) or susceptible (S) based on the appearance of black-brown cankers ≈2 months after inoculation with a bacterial suspension of loquat canker Group C. Cross combinations between resistant parents 'Champagne' and 'Shiromogi' and selfing of 'Shiromogi' produced all resistant seedlings. Most crosses between 'Shiromogi' and susceptible parents either produced only susceptible seedlings or segregated for resistance in a ratio of 1 R:1 S. Seedlings produced by selfing two of the susceptible parents segregated in a ratio of 1 R:3 S. These results indicate that the resistance to loquat canker Group C of 'Shiromogi' is conferred by a single recessive gene, designated pse-c. Based on the crossing tests, we conclude that resistant parents 'Shiromogi' and 'Champagne' are homozygous for pse-c; the susceptible parents 'Fukuharawase', 'Fusahikari', 'Gold Nugget', 'Kusunoki', Nagasaki No. 2, 'Tanaka', 'Tsukumo', and 'Yougyoku' are homozygous for Pse-c; and the other susceptible parentsinthis experiment ('Mogi', 'Nagasakiwase', Nagasaki No. 3, 'Taisho', and 75-142) are heterozygous. Based on the pedigree of 'Shiromogi' and the results reported here, pse-c is probably derived from 'Mogi', a major cultivar in Japan.