【摘要】 试验以刚开花的3年生巨峰葡萄实生苗为材料,分析其童区、转变区及成年区叶片中核酸、半乳糖醛酸和可溶性糖含量的变化.结果表明:每克鲜重叶片中RNA含量由童区至转变区急剧上升达最大值,在转变区保持在较高水平上,开花以上节位其含量降低,总核酸含量的变化也是如此;RNA/DNA比值在刚进入转变区达峰值,然后逐渐降低;半乳糖醛酸含量在童区和成年区均较低,在转变区出现最大值;非还原糖含量随阶段发育的提高而增加,在成年区大量开花部位降低,近植株顶端无花序部位复又增加;还原糖含量在进入转变区时达最大值,然后迅速降低,在转变区及成年区处于较低水平.更多还原

【Abstract】 Contents of nucleic acid,galacturonic acid and soluble sugar in le av es of three-year-old self-rooted Kyoho seedlings which had just entered into reproductive state were determined in the course of their phase development.The results showed:1)content of ribonucleic acid(RNA)dramatically soared from t he juvenile zone upward to a highest value at the transition zone and then did n ot declined until the apex was approached,and so did the total nucleic acid amo unt;2)a peak of RNA/DNA ratio occurred at the lowest node where the tendril ap peared,followed by a constant decline;3)content of galacturonic acid in leave s reached its maximum in the transition zone and then declined to and maintained at a relatively low level;4)there was a progressive increase of leaf non-red ucing sugar along the stem up from the juvenile zone to the adult zone which fol lowed by a decrease and a final increase as the apex was approached;5)amounts of reducing sugar and total A relative long period of juvenility was there in woody plants.Many researche s about the stage development of woody plants were performed[1～4].Passecker[5] suggested that there were juvenile,transition and adult zones from the base up to the top in apple seedling trees according to the fact that even the apple tr ee had been blossomed a juvenile character was still there in the base of the tr ee.Three major theories were proposed to explain the chemical control of the tr ansition to flowering[6].The “florigen/antiflorigen”concept suggested that th e floral promoter and inhibitor were each a simple,specific,and universal horm one that remain to be isolated and identified.The “nutrient diversion”hypothe sis postulated that floral induction,whatever the nature of the involved enviro nmental factors,was a means of modifying the source/sink relationships within t he plant in such a way that the shoot apex receives a better supply of assimilat es than under non-inductive conditions.While,the theory of “multi-factorial control”postulated that several chemicals-assimilates and unknown phytohormon es-participated in floral induction.Control of the transition to flowering in Sinapis alba was multi-factorial[6].Developmental transitions from juvenile to reproductive adult phase involved changes in the pattern of cellular differenti ation and organ formation and are strictly regulated by genes in the shoot apica l meristem[7,8].The molecular and genetic bases of the shoot apical meristem f ates have been widely investigated and several genes related to the switch to re productive phases have been characterized[9～12].The phase development of seedling trees was a sophisticated course including p hysiological and biochemical changes in different developmental phases and space s.Kessler and Monsellse[13] reported that the RNA content and the RNase activit y in apple and orange leaves were both higher in adult trees than in juvenile tr ees.Another study revealed,however,that little difference of DNA content was observed between the juvenile and adult tissues,and that the RNA/DNA ratio incr eased constantly with the development of seedling in several Pyrus species[14].Oligosaccharins have been proved to promote growth,development and reproducti on and the active component has been confirmed to be galacturonic acid[15].Some vegetative buds were turned into floral buds within tobacco explants in vitro b y adding to the cultural medium a very few oligosaccharide mixture that extracte d from oriental plane tree’s cell wall with alkaline lysis or enzymolysis,and i ndicated that oligosaccharide may be a kind of message to reduce flowering[16,17 ].Carbohydrate was believed to be the fundament of floral bud formation.In fru it trees a high level of carbohydrate in the shoots was considered to be necessa ry for flowering[18].In this study,changes of contents of nucleic acid,galacturonic acid and solu ble sugar in leaves of juvenile,transition and adult zones of ’Kyoho’seedling s which had just entered into reproductive state were determined.The reason of choosing grape seedling as research materials was that such seedling had a relat ive short period of juvenility,about 3～4 years,and had a conspicuously visual ized morphological mark of phase transition.It is known in grape fruit that ten dril is the heteromorphy of flower cluster.Normally,the lowest node on the mai n vine where the tendril appeared was not in accordance with the lowest node whe re the flower head appeared.In this study,therefore,the regions from base up to the node at which the lowest tendril appeared,from the end of former region to the node at which the flower head occurred and upward from the end of the sec ond region were referred to juvenile soluble sugar in leaves reached their peaks at transition zone where the tendr il appeared for the first time and then declined to and maintained at a relative low level.更多还原