Differentiation of the seed coat and composition of the mucilage of Lepidium perfoliatum L.: a desert annual with typical myxospermy.
Myxospermy is an important feature in seeds of many plant species grown in desert region. Fertilization can initiate differentiation of the seed coat epidermis into a specialized cell type with mucilage production. In the present study, comprehensive analyses were performed on the seed coat differentiation, mucilage production and composition, and seed germination in Lepidium perfoliatum (Brassicaceae), a desert annual with typical myxospermy in China. First, results indicated that mucilage was secreted uniformly at the outer tangential wall, resulting in compression of the cytoplasm to the bottom of the epidermal cells. Secondly, the inner tangential wall and two radial walls of the subepidermal cells were apparently thickened by production of a secondary cell wall material, which resulted in a 'typical' palisade appearance. Thirdly, immunohistochemical staining combined with the enzymatic digestion and infrared spectrum analysis of the mucilage indicated that, while one important component of the seed coat mucilage in L. perfoliatum was pectin, it also contained β-1,3-d-glucan and xyloglucan. Finally, seed germination showed that seeds with mucilage displayed significantly higher germination percentage than that of demucilaged seeds in abundant or excess water conditions. These results suggest that the possible ecological role of mucilage in L. perfoliatum is in the adaptation to habitats with well-watered and water-logged conditions, rather than water stress.
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China College of Life Science, Nankai University, Tianjin 300071, China.
Daihong
D
Huang
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China.
Cui
C
Wang
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China.
Junwen
J
Yuan
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China.
Jing
J
Cao
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China lanhaiyan@xju.edu.cn.
Haiyan
H
Lan
D000269:Adhesives / Q000737:chemistry / Q000378:metabolism; D003889:Desert Climate; D018525:Germination / Q000502:physiology*; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D029686:Lepidium / Q000737:chemistry / Q000145:classification / Q000502:physiology*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D012639:Seeds / Q000737:chemistry / Q000502:physiology*; D013045:Species Specificity; D013312:Stress, Physiological / Q000502:physiology*; D014867:Water / Q000737:chemistry / Q000378:metabolism
D000269:Adhesives; D006023:Glycoproteins; D011134:Polysaccharides; D014867:Water
Lepidium perfoliatum; germination; mucilage; seed coat; β-1,3-d-glucan