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Myricaria laxiflora (Tamaricaceae) is an endangered plant that is narrowly distributed in the riparian zone of the Three Gorges, along the Yangtze River, China. Using bright-field and epifluorescence microscopy, we investigated the anatomical and histochemical features that allow this species to tolerate both submerged and terrestrial environments. The adventitious roots of Myr. laxiflora had an endodermis with Casparian bands and suberin lamellae; the cortex and hypodermal walls had lignified thickenings in the primary structure. In the mature roots, the secondary structure had cork. The apoplastic barriers in stems consisted of a lignified fiber ring and a cuticle at the young stage and cork at the mature stage. The leaves had two layers of palisade tissue, a hyaline epidermis, sunken stomata, and a thick, papillose cuticle. Aerenchyma presented in the roots and shoots. Several Myr. laxiflora structures, including aerenchyma, apoplastic barriers in the roots and shoots, were adapted to riparian habitats. In addition, shoots had typical xerophyte features, including small leaves, bilayer palisade tissues, sunken stomata, a thick, papillose cuticle, and a hyaline epidermis. Thus, our study identified several anatomical features that may permit Myr. laxiflora to thrive in the riparian zone of the Three Gorges, China.

Background: Euphorbia pulcherrima is highly ornamental value of poinsettia flower, which posses colorful bracts and low temperature resistant leave. Its embryos or adventitious buds were cultivated mainly from stems, petioles and tender buds. The cultivation of seedlings is studied firstly for improving the quality of Poinsettia. Methods: A rapid and reproducible regeneration system of leaves and stems with buds has been established. There is a comparative analysis of the results of tissue culture of different varieties of Poinsettia. Result: The best medium component of hormones about leaf callus of poinsettia inducing cluster buds formation comprise 6-BA 1.0 mg/L, KT 0.4 mg/L, NAA 0.1 mg/L and 2,4-D 0.05 mg/L. Its medium component inducing cluster buds proliferation include 6-BA 1.2 mg/L and NAA 0.05 mg/L. The medium component about stem with bud inducing cluster buds to germinate comprise 6-BA 1.5 mg/L and NAA 0.1 mg/L. Its medium component inducing cluster buds proliferation include 6-BA 1.0 mg/L and NAA 0.05 mg/L. The different hormones and different addition level of Ac have effect on the length of the root and quantity of the first level root and the second level root.

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