Chen Zhenghua

Meiosis-like reduction during somatic embryogenesis of Arabidopsis thaliana

SummarySomatic meiosis-like reduction was observed in some cells of the embryogenic callus of Arabidopsis thaliana. Two types were identified. One type was somatic chromosome reductional grouping, in wich the chromesomes in a cell were separated direetly at either prophase or metaphase. Chromosome reductional grouping happened more frequently in polyploid cells, and the morphology of the chromosomes did not show the role of the spindle fibers. The other type was somatic meiosis which was analogous to the process of gametogenesis, characterized by the pairing and synapsis of homologous chromosomes. The roles of somatic meiosis-like reduction in somatic embryogenesis and somaclonal variations are discussed

Studies on Embryogenesis of Woody Plants in China

During the last decade induction of somatic embryogenesis has been carried out in a number of plant species in China. Several features of embryogenesis of woody plants are described. The embryogenesis should go through two stages, that is, the young and the mature embryo stage, before they can be transferred to plantlet forming medium. Some factors affecting the induction freguency of embryogenesis, such as light and dark, temperature, medium and hormones are discussed. The causes of abnormal embryoid formation are also mentioned.

Chromosome microdissection by laser microbeam, chromosomal fragment isolation and amplificationin vitro in barley (Hordeum vulgare L.)

A method for microdissection, isolation and amplification of plant chromosomal fragments using laser microbeam and a glass microneedle was established. Firstly, 7H chromosome of barley (Hordeum vulgare L.) was dissected by Nd: YAG laserbeam with suitable parameters and the fragment comprising a satellite was isolated with a glass microneedle which was fixed on a micromanipulator. Then, the chromosomal fragment DNA was amplified by LA-PCR (linker adaptor PCR) for two rounds. The size of the DNA fragments of PCR products varied from 500–3 000 bp and the PCR products originated from the genome of barley were verified by Southern hybridization. Compared with previous reports, there are some advantages in this research. The performance is easier. the dissection is more precise and the cost is low. It also permits efficient amplification with only one single chromasome fragment. Laser microbeam-glass microneedle method may be useful in the microdissection of special chromosome regions, especially in plants with middle or small chromosomes.