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At least 505 records · Page 28Linked to original sources
PubMed2005

Transformation of a recalcitrant grain legume, Vigna mungo L. Hepper, using Agrobacterium tumefaciens-mediated gene transfer to shoot apical meristem cultures.

The efficiency of Vigna mungo L. Hepper transformation was significantly increased from an average of 1% to 6.5% by using shoot apices excised from embryonic axes precultured on 10 microM benzyl-6-aminopurine (BAP) for 3 days and wounded prior to inoculation in Agrobacterium tumefaciens strain EHA105 carrying the binary vector pCAMBIA2301, which contains a neomycin phosphotransferase gene (nptII) and a beta-glucuronidase (GUS) gene (gusA) interrupted by an intron. The transformed green shoots that were selected and rooted on medium containing kanamycin, and which tested positive for nptII gene by polymerase chain reaction, were established in soil to collect seeds. GUS activity was detected in whole T(0) shoots and T(1) seedlings. All T(0) plants were morphologically normal, fertile and the majority of them transmitted transgenes in a 3:1 ratio to their progenies. Southern analysis of T(1) plants showed integration of nptII into the plant genome.

Adenine↗
PubMed2003

Preparation of chromosomes from plant leaf meristems for karyotype analysis and in situ hybridization.

A reliable method for preparing metaphase chromosomes from plant leaf tissues is described. The chromosomes are suitable for karyotype analysis and gene mapping by fluorescence in situ hybridisation (FISH). The method is based on enzymatic digestion of young leaf tissues (shoot-tips) after which the resulting protoplasts are treated hypotonically before being dropped onto microscopic slides. Compared to root-tip chromosomes, leaf chromosomes tend to be longer, or less condensed, and hence more karyotypically differentiated. Metaphase index in young leaf tissues is also very high. Metaphase spread consists of evenly and well-distributed chromosomes and this allows accurate counting. The plant used to demonstrate this method is birch (Betula L.), a group of tree species that has extremely small chromosomes. Root-tip chromosomes of these plants are difficult to obtain, as cutting does not produce roots readily. Seedling chromosomes do not represent the same genomic constitution as their mother trees due to introgressive hybridisation. Furthermore, sample collection in the field is convenient and actively growing leaf buds are available throughout the growing season. FISH experiments with these leaf chromosomes also give good results comparable to those obtained with root-tip chromosomes or even better as mapping on long or extended chromosomes has high resolution in general. Mapping of the 16S-28S ribosomal genes on birch leaf chromosomes has been shown to differentiate between birch species and therefore can accurately confirm their interspecific hybrids.

Betula↗
PubMed2006

Comparative expression profiling in meristems of inbred-hybrid triplets of maize based on morphological investigations of heterosis for plant height.

Heterosis, the superior performance of hybrids as compared to their parental mean is an agronomically important phenomenon well-described morphologically. However, little is known about its molecular basis. We investigated four genetically unrelated maize (Zea mays L.) inbred lines and their F(1) crosses both at the phenotype and transcriptome level, focusing on plant height (PHT) component traits. Substantial mid-parent heterosis (MPH) was found for all parent-hybrid triplets for PHT in the range of 37.9-56.4% in the field and 11.1-39.5% under controlled greenhouse conditions. Analyses of heterosis for number and length of internodes showed two to three times higher MPH in the field as compared to the greenhouse. All three traits exhibited high heritabilities, highest for PHT 95-98%. Two methods for gene expression quantification were applied. High-density cDNA uni-gene microarrays containing 11,827 ESTs were utilized for the selection of differentially expressed genes related to heterosis for PHT. For the four triplets with eight possible parent-hybrid comparisons we identified 434 consistently differentially expressed genes with a p < or = 0.05. Microarray results were used to verify the dominance/overdominance hypothesis. In our study, more than 50% genes showed overdominance, 26% partial dominance, 12.6% complete dominance and 10.2% additive gene action. Moreover, more consistently differentially expressed genes were detected in related triplets, sharing one parent, than in unrelated triplets. Quantitative RT-PCR was applied in order to validate microarray results. The role of the differentially expressed genes in relation to heterosis for PHT is discussed.

Gene Expression Profiling↗