中文摘要：

为了解狗蔷薇（Rosa canina L.）类原球茎发生机制,以建立月季高效再生体系,探讨了根尖内部维管组织在狗蔷薇愈伤-不定根根尖膨大发育为类原球茎过程中所起作用。剪切试验发现,脱离愈伤的狗蔷薇不定根根尖不能诱导类原球茎形成;桥接培养表明,通过维管组织向根尖运输外源激素TDZ诱导类原球茎发生的效率高于共质体运输方式;TIBA（2,3,5-triiodobenzoic acid）处理限制了根尖维管组织向分生区的延伸速度,并最终影响了类原球茎发生率;在类似狗蔷薇愈伤-不定根结构的蒺藜苜蓿（Medicago truncatula Gaertn.）根段-不定根上也重现了根尖被诱导发育为绿色球体过程。由此表明,愈伤-不定根中完整的维管组织是狗蔷薇类原球茎发生的结构基础之一,揭示获得与愈伤-不定根类似的内部结构和组合模式的外植体（如毛状根）,并将其视为整体进行诱导培养,是建立月季类原球茎再生体系的前提之一。

英文摘要：

Protocorm-like bodies（PLBs）regeneration system has been established for several Rosa spp.More understandings on the process of PLBs formation,including what roles of vascular tissue of rhizoids play in the incipient stage,will contribute to the establishment of PLBs protocols in cut roses.We proposed a hypothesis named ‘vascular channel＇：Through the vascular tissue in R.canina rhizoids,high concentration of TDZ（thidiazuron）containing in medium was quickly and largely transported to rhizoid meristem,resulting in the rhizoid meristem cells shifting their functions,which initiated PLBs development.In the present study,we provided some evidence on the rationality of this hypothesis.Both whole callus-free rhizoids and its segments were cultured either vertically or horizontally on the induction medium with TDZ,no PLBs formed.During the bridging culture,the efficiency of PLBs induction was higher in the callus-rhizoids relied on apoplastic transport than symplastic transport.The TIBA（2,3,5-triiodobenzoic acid）treatment had suppressed the elongation of vascular tissue towards to the rhizoid meristem,which finally led to a low rate of PLBs formation.Furthermore,the partial process of PLBs system was reproduced in Medicago truncatula Gaertn.,their rhizoid tips derived from the rhizoid segment were induced into green ellipsoidal bodies.These findings indicated that the vascular tissue of R.caninacallus-rhizoids being capable of rapidly delivering nutrients and hormones was critical for PLBs development,and it must be closed and complete from the callus to the rhizoid tip.Based on this,we proposed that the prerequisite for achieving a PLBs system of cut roses is to induce callus-rhizoids or similar explants possessing a transporting system that could rapidly aggregate hormones and nutrients.