Cloning and Sequence Analysis of Plastidic Glutamine Synthetase Induced by Nitrogen in Sugar Beet(Beta vulgaris L.) Cloning and Expression Profile Analysis of Ghpg2 Gene Associated with Fertility in Cotton(Gossypium hirsutum L.) Characterization of Evolution and Tissue-Expression of Rice (Oryza sativa L.) α-Amylase Genes Expression Profile of PtLFY in Floral Bud Development Associated with Floral Bud Morphological Differentiation in Populus tomentosa