A high-frequency plantlet regeneration protocol was developed for black pepper (Piper nigrum L.) through cyclic secondary somatic embryogenesis. Secondary embryos formed from the radicular end of the primary somatic embryos which were originally derived from micropylar tissues of germinating seeds on growth regulator-free SH medium in the absence of light. The process of secondary embryogenesis continued in a cyclic manner from the root pole of newly formed embryos resulting in clumps of somatic embryos. Strength of the medium and sucrose concentration influenced the process of secondary embryogenesis and fresh weight of somatic embryo clumps. Full-strength SH medium supplemented with 1.5% sucrose produced significantly higher fresh weight and numbers of secondary somatic embryos while 3.0 and 4.5% sucrose in the medium favored further development of proliferated embryos into plantlets. Ontogeny of secondary embryos was established by histological analysis. Secondary embryogenic potential was influenced by the developmental stage of the explanted somatic embryo and stages up to "torpedo" were more suitable. A single-flask system was standardized for proliferation, maturation, germination and conversion of secondary somatic embryos in suspension cultures. The system of cyclic secondary somatic embryogenesis in black pepper described here represents a permanent source of embryogenic material that can be used for genetic manipulations of this crop species.

Summary Chromosme numbers in 22 germplasm collections and 28 open-pollinated seedling progenies of turmeric (Curcuma longa L.) were determined by counting the chromosomes of somatic metaphase plates. Among the germplasm collections analyzed 20 have 2nϭ63, the accepted chromosome number of turmeric, 1 collection was 2nϭ61 and another 1 was 2nϭ84. The seedling progenies showed various chromosome numbers ranging from 2nϭ63 to 2nϭ86, of which 2nϭ84 was the most frequent. The role of abnormalities during triploid chromosomes segregation in generating chromosome number variation among open pollinated seedling progenies is discussed.

No abstract

No abstract