Light signal perception in Arabidopsis rosettes

Light signals are important signals for future and present competition. We used an architectural model of Arabidopsis development to show that vertical growth of neighboring vegetation is more important than proximity for early detection of competition. Self-signaling is greatly enhanced when own organs grow more vertically, and signal strength differs between signal perception at the apex compared to the leaves

An Improved Agrobacterium tumefaciens Mediated Transformation of Artemisia annua L. by Using Stem Internodes as Explants

Transformation of Artemisia annua, which produces the sesquiterpenoid endoperoxide artemisinin widely used for the treatment of malaria, has been hampered by the low efficiency of adventitious shoot and root formation on a selective medium containing additional compounds for Agrobacterium decontamination. Here we identified several factors which were all shown to be of importance for optimization of Artemisia annua transformation. Results indicated that stem internodes showed better resistance capacity to Agrobacterium decontaminator than leaves did. Agrobacterium tumefaciens with an optical density (OD) value of 0.2–0.5 plus 100 µmol of acetosyringone per litre of solution gave the best transformation efficiency. Moreover, kanamycin at 30 mg/l in the culture medium was effective in suppressing the growth of non-transformed tissue. Furthermore, transgenic shoots required an early induction of rooting. In addition, dimethyl sulphoxide considerably improved the rooting of shoots. The present work provides rapid and reproducible transformation and regeneration of A. annu

Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.