甜瓜子叶离体培养直接再生不定芽的形态学和解剖学观察

Developmental Morphology and Anatomy of Direct Shoot Organogenesis from Melon Cotyledon

对甜瓜品种“西莫洛托”子叶离体培养直接再生不定芽过程进行了形态学和解剖学观察。结果表明 :以子叶远轴面接触培养基培养能直接再生不定芽 ,以子叶近轴面接触培养基培养只能得到无序组织块 ;不定芽再生过程中 ,培养 4 d时 ,子叶变绿 ,但还不见有细胞分裂。约 6 d时 ,在子叶外植体的形态学下端切口处的近轴面观察到有局部的表皮细胞和亚表皮细胞分裂活跃 ,初步形成了拟分生组织。 7～ 9d时 ,这些拟分生组织形成了肉眼可见的小突起。 10～ 14 d时 ,这些突起变得狭长 ,发育成幼叶或叶状体 ,它们在外植体上成簇存在 ,但此时还没有典型的“芽”结构出现。 15～ 2 0 d时 ,成簇突起形成幼叶丛 ,一些幼叶和叶状体的近轴面的基部出现叶腋分生组织。这时将外植体转入伸长培养基 ,3～ 5 d后 ,幼叶充分展开 ,成丛叶状 ,多个叶腋分生组织同时发育成芽。再过 2～ 7d,相继有不定芽从丛叶外植体上伸长 ,将伸长的不定芽切下 ,可促使外植体上的其它不定芽伸长。

The morphology and anatomy of direct shoot organogenesis from quiescence cotyledon explants of melon (Cucumis melo L.) cv.ximoluotuo cultured in vitro was studied.Buds regene- rated when the explants were cultured with the abaxial side towards the inducing media.By 4 d on MS media with BA 0.5 mg/L,the explants turned green but there were no cell divisions observed.By 6 d,cells in the epidermal and subepidermal laryer on the adaxial side of the explant,near the cut edge where is morphological down divided and became some meristemoids.By 7~ 9 d,the meristemoids became small visible protuberances.By 10~14 d,more protuberances appeared and clustered near the cut edge of the explant.Some of them became long and thin and some developed into distinguished young leaves.But there were no typical bud structures by this time.By 15~20 d,a cluster of young leaves and leaf-like organs formed and several axillary meristems initiated at the base of the adaxial side of these young leaves.When transferring these explants onto the MS media with BA 0.05 mg/L,the young leaves extended fully and the whole explant presented'bush-like'3~5 d later.Buds elongated and shoots can be obtained with another 2~7 d.Cutting the elongated buds could promote other buds to develop on one explant.