摘要
外源激素在诱导再生花芽花器官发生和控制它们的数目中的关键作用被进一步证实。首先通过 2mg/L6_BA和 0 .1mg/L 2 ,4_D的激素组合诱导风信子 (HyacinthusorientalisL .cv .Whitepearl)花芽从花被外植体发生 ,然后保持这种激素浓度 ,成功地控制了 10 0多片花被片的连续发生 (自然情况下一个风信子花芽仅有 6片花被片 )。改变激素浓度 ( 2mg/L 6_BA和 0～ 0 .0 0 0 1mg/L 2 ,4_D)终止了花被片的连续发生和诱导了雄蕊的发生。保持被改变的激素浓度成功地控制了 2 0多枚雄蕊的连续发生 (自然情况下一个风信子花芽仅有 6枚雄蕊 )。实验表明 ,再生花芽中同一种花器官的数目是可以通过控制外源激素浓度来控制的 ,而被诱导的同一种花器官数目的多少不会影响不同花器官的分化次序。根据过去十多年中利用外源激素控制风信子花被外植体和再生花芽两者中花器官分化所做的系统研究 ,作者对植物激素在花发育中控制不同的花器官自动按程序分化中的作用提出了新的看法 ,要点如下 :1.植物花芽的发育是它各轮花器官自动按程序从花的分生组织分化的过程 ;2 .离体培养的实验表明 ,花芽中不同花器官的分化需要不同浓度的植物激素 ,当诱导某种花器官分化的激素浓度保持不变时 ,花的分生组织只是连续地重复分化这种花器官不断?
The critical role of exogenous hormone on inducing the initiation of different floral organs in the regenerated flower bud and controlling their numbers was further evidenced. The initiation of the flower buds was first induced from the perianth explants of Hyacinthus orientalis L. cv. White pearl by a combination of 2 mg/L 6_BA and 0.1 mg/L 2,4_D, and then a continuous initiation of over 100 tepals (a flower bud of H. orientalis in situ has only 6 tepals) was successfully controlled by maintenance of such a hormone concentration. However, a change of hormonal concentration (2 mg/L 6_BA and 0-0.000 1 mg/L 2,4_D) caused cessation of continuous initiation of the tepals but gave rise to induction of stamen initiation. Keeping the changed hormone concentrations could successfully control the continuous initiation of over 20 stamens (a flower bud of H. orientalis in situ has only 6 stamens). The experiment showed that the number of identical floral organs in the regenerated flower buds can be controlled by certain defined concentrations of the exogenous hormones, and the amount of the induced identical floral organs has no effect on the differentiation sequence of the different floral organs in the regenerated flower bud. Based on a systematic research on controlling the differentiation of the floral organs from both the perianth explants and the regenerated flower buds by the exogenous hormones in H. orientalis over the past decade, the authors put forward here a new idea on the role of phytohormone in controlling the automatic and sequential differentiation of the different floral organs in flower development. The main points are as follows: 1. the development of flower bud in plant is a process in which all of the floral organs are automatically and sequentially differentiated from the flower meristem. 2. Experiments in vitro showed that the effect of exogenous hormones in controlling the initiation of different floral organs is strictly concentration dependent, i.e., one kind of the floral organ can continuously and repeatedly initiate from the flower meristem as long as it is maintained in that specific concentration of the exogenous hormone which is suitable for the initiation of that particular kind of floral organ. 3. It shows that the flower buds in situ must be automatically able to adjust the endogenous hormonal concentrations just after the completion of the differentiation of one whorl of floral organ to suit the differentiation of the next whorl. Thus, the phytohormone in different concentrations takes after many change_over switches of the organ differentiation and plays a connective and regulatory role between the differentiation of every two whorls of the floral organ. In other words, these change_over switches play the roles of inhibiting the expression of the genes which control the initiation of the floral organs in the first whorl, meanwhile, activating the expression of the genes which control the initiation of the floral organs in the second whorl during the successive initiation of the different floral organs from the flower bud. It results in the automatic and sequential initiation of the various floral organs from the floral meristem.
基金
中国科学院"九五"基础研究项目
科学技术部"九五"攀登预选项目&&
关键词
风信子
花器官分化
花芽发育
外源激素
基因表达
Hyacinthus orientalis
flower bud regeneration
initiation of floral organ
role of phytohormone
flower bud development
