大花四照花種子休眠解除過程中種皮和胚乳結構變化1)

周健　代松　錢存夢　蘇友誼　李淑嫻

(南京林業大學，南京，210037)

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大花四照花種子休眠解除過程中種皮和胚乳結構變化1)

周健代松錢存夢蘇友誼李淑嫻

(南京林業大學，南京，210037)

摘要為探討種皮、胚乳對大花四照花種子萌發的影響，以不同解除休眠處理后大花四照花種子為材料，開展了種皮透水性試驗，并分別對其種皮和胚乳進行了掃描電鏡(SEM)和透射電鏡(TEM)觀察。結果表明：大花四照花種皮存在透水性障礙。掃描電鏡觀察發現，其種皮由外到內依次為表皮層、柵欄層、薄壁細胞層以及纖維細胞層。表皮層由多層排列緊密的厚壁細胞組成。柵欄層則由單層緊密排列的長柱狀大石細胞構成，柵欄層可能是阻礙種子吸水的主要原因。酸蝕和低溫層積對種皮結構都會產生一定影響。低溫層積處理能破壞種皮表層結構，同時還能改變內部柵欄層細胞結構，種子低溫層積90 d后，種皮出現裂縫直達內部薄壁細胞層。透射電鏡觀察發現，低溫層積過程中，胚乳細胞內大分子營養物質不斷降解，細胞內物質代謝速度逐漸加快，低溫層積90 d，營養物質基本降解，線粒體、內質網、高爾基體等細胞器相繼出現，種子休眠解除。濃硫酸酸蝕能加快大花四照花種皮結構的改變和胚乳細胞內物質代謝，促進該種子休眠的解除。

關鍵詞大花四照花；種子休眠；種皮；胚乳；細胞結構

分類號S722.1

Ultrastructure Changes of Seed Coat and Endosperm onCornusfloridaSeed during Dormancy Breaking//

Zhou Jian, Dai Song, Qian Cunmeng, Su Youyi, Li Shuxian

(Nangjing Forestry University, 210037 Nanjing, P. R. China)//Journal of Northeast Forestry University，2016,44(5)：34-38.

In order to investigate the effect of seed coat and endosperm on the germination ofCornusfloridaseeds, the ultrastructure of seed coat and endosperm ingredients ofC.floridaseed with different treatments was systematically investigated by using scanning electron microscope (SEM) and transmission electron microscope (TEM), combining with the study of water permeability. Results of water uptake revealed the seed coat ofC.floridcould retard water uptake. By SEM images, from the exterior to the interior, the seed coat ofC.floridconsisted of four layers: the epidermal layer, the palisade layer, the parenchymatous layer and the fibrocyte layer. The epidermal layer consisted of multilayer sclerenchymatous cell. The palisade layer consisted of a monolayer macrosclereids with thick walls elongated longitudinally, and it may be the main barrier controlling the entrance of water through seed coat. Both of cold stratification and acid etching could change the seed coat structure ofC.florid. The epidermal layer and the palisade layer ofC.floridseed coat were damaged after treated by concentrated sulphuric acid. Cold stratification could destroy the out layer ofC.floridseed coat and change the structure of palisade layer to some extent. When seeds were cold stratified at 5 ℃ for 90 d, the cracks were appearing through the epidermal layer and the palisade layer. By TEM, with theC.floridseed dormancy released, macromolecule nutrients in the endosperm gradually decomposed and metabolism boosted. When seeds were cold stratified for 90 d, nutrients in the endosperm gradually decomposed, mitochondria, endoplasmic reticulum, golgi apparatus appeared, and its dormancy was broken. In addition, proper sulfuric acid treating could accelerate the break ofC.floridseed dormancy by expediting the change of seed coat structure and the metabolism of endosperm cell.

KeywordsCornus florida; Seed dormancy; Seed coat; Endosperm; Cell structure

大花四照花(Cornusflorida)為山苵萸科(Cornacease)山茱萸屬(Cornus)四照花亞屬落葉喬木，又名多花梾木，多花狗木。大花四照花原產于北美洲東部，喜濕潤半陰的環境，早春開花，傘形花序，野生種外面的4個苞片剛開始開放時為綠色，后逐漸變為白色，為適應觀賞的需要，又培育出苞片為粉紅色或大紅色的品種。……