Histological analysis of hulled and hull-less squash seed coat

Li, X. . Dept. of Horticulture; Ge, Y. . Dept. of Horticulture; Gui, M. . Dept. of Life Sciences; Cui, C.S.; Qu, S.P.

Histological analysis of hulled and hull-less squash seed coat

2013

Li, X. (Northeast Agricultural Univ., Harbin (China). Dept. of Horticulture) | Ge, Y. (Northeast Agricultural Univ., Harbin (China). Dept. of Horticulture) | Gui, M. (Northeast Agricultural Univ., Harbin (China). Dept. of Life Sciences) | Cui, C.S. | Qu, S.P.

Differences in the structures of seed coat from one hull-less genotype and three hulled-seeded genotypes of squash (Cucurbita pepo and C. maxima) were examined in mature seeds using paraffin sectioning and scanning electron microscopy. Histological investigations demonstrated that squash seed coat normally comprise five layers, including the epidermis, hypodermis, sclerenchyma, parenchyma, and chlorenchyma. Three layers of hypodermis, sclerenchyma, and parenchyma cells were strongly or partially lignified and maintained their integrity to form the hard, leathery hull that was characteristic of hulled-seeded squash seeds. On the contrary, three layers of hypodermis, sclerenchyma and parenchyma cells were collapsed in hull-less squash seed coat due to a lack of lignin deposition and this seed coat contained only one or two layers of degenerated parenchyma cells. In addition, the seed margin, a specialized part of the seed coat in mature seeds, exhibited the same structural differences as seed coats in hulled vs. hull-less seed types, except for the presence of a large, circular vascular bundle in the parenchyma of both types of hulled and hull-less seed coats.

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