Somaclonal Variation and Stability of GUS Gene Expression in Transgenic Agapanthus (Agapanthus praecox ssp. orientalis) Plants at the Flowering Stage
Agapanthus (Agapanthus praecox ssp. orientalis), a liliaceous perennial, is cultivated as an ornamental plant because of its beautiful, blue-violet to white flowers. Transgenic agapanthus plants containing the GUS reporter gene under the control of CaMV35S promoter have previously been produced via Agrobacterium-mediated genetic transformation. These transgenic plants have been cultivated for 5 yr after transplantation to pots, and 12 transgenic plants derived from five independent lines were subjected to morphological characterization, and examination of the ploidy level, pollen fertility and stability of GUS gene expression at the flowering stage. Transgenic plants of four lines kept the diploid level, but those of the remaining one line were tetraploid. For all of the 12 transgenic plants, some morphological variations were observed both in vegetative and floral organs such as decreased number of leaves per inflorescence, smaller leaves, shorter inflorescence stalks, decreased number of florets per inflorescence and smaller florets. Pollen fertility of all the transgenic plants was below 5%. All the 12 transgenic plants showed stable expression of the GUS gene in leaves, roots, tepals, pistils, and stamens, as indicated by histochemical GUS assay, fluorometric GUS assay, and/or real-time RT-PCR analysis. No apparent GUS gene silencing was observed in transgenic agapanthus plants even after 5 yr of cultivation, which is essential for demonstrating the validity of genetic transformation for the improvement of perennial flower crops like agapanthus. Shiro Mori, Eriko Oka, Hiroto Umehara, Sakae Suzuki, Hitoshi Kobayashi, Yosuke Hoshi, Masayoshi Kondo, Yosuke Koike and Masaru Nakano. Somaclonal variation and stability of GUS gene expression in transgenic agapanthus (Agapanthus praecox ssp. orientalis) plants at the flowering stage, In Vitro Cellular & Developmental Biology-Plant, 43:79 – 88, 2007.
In Vitro Propagation of Acer grandidentatum Nutt
Bigtooth maple (Acer grandidentatum Nutt.) occurs naturally in the drier regions of North America. Thus, bigtooth maple might thrive in managed landscapes in arid and semi-arid regions. Excellent nursery selections of bigtooth maples are not readily available. Nurseries provide only seedlings grown from wild-crafted seeds and grafted trees of the lone variety, A. grandidentatum var. sinuosum. Grafted trees are weak-wooded and susceptible to iron deficiency. Although micropropagation might ensure that stable and desirable bigtooth maple selections are available, clonal propagation of the hard maple group, to which bigtooth maple belongs, has been notoriously difficult. There are no published reports on the micropropagation of bigtooth maples. So, we wanted to find out whether micropropagation of bigtooth maples would be feasible. We used greenhouse-grown seedlings originating from seeds collected in New Mexico, Texas and Utah. Double-node explants (four axillary buds) were excised from the seedlings, sterilized and placed on Driver Kuniyuki Walnut (DKW), Linsmaer-Skoog, Murashige-Skoog or Woody Plant tissue culture media. Cultures were transferred to fresh media every two days for six days to reduce phenolic accumulation. Shoot sprouting and proliferation were observed for 180 days. The location from which explants were excised did not affect shoot proliferation. This suggests that explants selected from any part of the donor plant will perform equally well in culture. Bigtooth maple axillary buds consistently sprouted at higher rates on DKW containing cytokinin. About three shoots per double-node explant sprouted on DKW. We selected shoots from established cultures and placed them on DKW without plant growth regulators for 30 days. We then placed those shoots on DKW with indole acetic acid for fifteen days to induce rooting. Rooted shoots were successfully transferred to a growing substrate of 1:1 perlite and peatmoss. Although only 15% of shoots rooted, our micropropagation protocol is one way to provide a selected number of bigtooth maple clones. Clare Annabel Bowen-O’Connor, John Hubstenberger, Cynthia Baca, Dawn Marie VanLeeuwen, and Rolston St. Hilaire. In Vitro Propagation of Acer grandidentatum Nutt, In Vitro Cellular & Developmental Biology-Plant, 43: 40 – 51, 2007.
Endosymbiotic Fungi Structurally Integrated with Leaves Reveals a Lichenous Condition of C4 Grasses
Scientists of the USDA-ARS, Jornada Experimental Range, Las Cruces, NM are studying endophytic fungi that are intrinsically integrated with cells and tissues of dominant range plants native to the Northern Chihuahuan Desert. Our paper illustrates a lichen-like fungal association on the leaves on native C4 grasses. This suggests that these fungi may have regulatory function in the evolutionary development of these grasses. The goal of this group is to investigate the potential of unique fungi that appear to regulate plant performance under chronic nutrient, water and temperature stress imposed by this desert environment. Special interest focuses on how these organisms affect plant community structure and their potential use in re-establishing declining native grasses in degraded rangelands. Jerry Barrow, Mary Lucero, Issac Reyes-Vera, and Kris Havstad. Endosymbiotic Fungi Structurally Integrated with Leaves Reveals a Lichenous Condition of C4 Grasses, In Vitro Cellular & Developmental Biology- Plant, 43:65 – 70, 2007.