Stable transformation of mature zygotic embryos and regeneration of transgenic plants of chir pine (Pinus roxbughii Sarg.).

A particle inflow gun was used to transfer the plasmid pAHC25 containing the bar gene conferring resistance to glufosinate and the gusA reporter gene, each driven by the maize ubiquitin promoter, to mature embryos of Pinus roxburghii (chir pine). High levels of transient expression were obtained when embryos were cultured for 6 days on 10 microM benzyl adenine-containing medium and then exposed to high osmoticum (0.5 M sucrose) before and after bombardment. Selection on medium containing Basta enabled recovery of stably transformed shoots, both from the epicotyl and from adventitious buds. The primary transformed shoots from the epicotyl were multiplied via axillary shoots. Transformation was confirmed by histochemical staining for beta-glucuronidase (GUS) activity, by polymerase chain reaction (PCR) amplification of fragments of gusA and nos terminator, and by the resistance of needles to Basta.

Floral biology and breeding behavior in the bamboo Dendrocalamus strictus Nees.

Floral biology and breeding behavior were studied in the bamboo Dendrocalamus strictus Nees. The inflorescence in this species is a large branching panicle. Fertile florets are intermixed with smaller sterile ones. There are six stamens. The ovary is stipitate and turbinate. The style is long and the stigma is bifid and plumose. Dendrocalamus strictus is typically dichogamous and protogynous. The gynoecium matures 3-4 days before the androecium, effectively preventing self pollination. Flower bloom, which took place over a period of 2 to 3 h, was dependent on air temperature and only occurred between 0600 and 1300 h. Dendrocalamus strictus is anemophilous. Flowers in the male phase were visited by insects. These insects completely neglected the flowers at the female phase. The insects fed on the pollen and were not pollen vectors. When wind was excluded by enclosing the inflorescences in bags there was no seed set, indicating that cross pollination by wind is necessary for fertilization and that parthenocarpy and apomixis are not occurring in this species. Pollen fertility was about 98% as indicated by staining fresh pollen at the time of anther dehiscence and pollen release with Alexander's stain (Alexander 1969). When placed on a modified Brewbaker-Kwak medium containing 1% glucose, the pollen grains germinated well, and the pollen tubes grew to 15-20 times the diameter of mature pollen grains. Although profound protogyny has its disadvantages in times of sporadic flowering, it can be useful in breeding programs because it eliminates the need for emasculation.