花粉分化的和脱分化的第一次有丝分裂的比较观察

本文通过对小麦花粉正常分化过程的第一次有丝分裂过程的活体连续观察,及与离体培养条件下,脱分化的第一次有丝分裂过程的比较,找到了这两次分裂在细胞学上的差异。这些差异主要表现在核的位置,细胞质的位置,纺锤体的轴向及新细胞壁的形状与位置上。作者认为:(1)差异从细胞分裂的一开始就存在,因此致使细胞脱分化的关键时刻不在细胞周期的分裂期而在间期,从而不同意纺锤轴轴向的改变是脱分化启动原因的说法,(2)造成差异的原因可能与脱分化时丧失极性有关。     

菸草(Nicotiana tabacum L.)离体花粉诱导形成单倍体植株的研究

通过菸草离体花粉的液体培养,诱导花粉粒形成胚状体而后发育成小植株.对花粉离体前在花药中作不同时间预培养的各组试验,作了详细的细胞学观察,并对离体培养中影响花粉粒脱分化的因素进行了讨论。     

离体培养中胡萝卜细胞脱分化状态下无丝分裂的活体连续观察

本文对离体培养的胡萝卜细胞在脱分化状态下进行的劈裂式无丝分裂,进行了全过程的活体连续观察。观察的细胞取自根的愈伤组织。它们首先在微室中培养成活,进行不断地细胞分裂,然后通过相差显微镜进行活体细胞分裂全过程的观察。观察表明:按细胞学特点,整个分裂过程可以分成前期、中期、后期和末期四个时期。在整个过程中未见到染色体和纺锤体。每个时期所需要的时间已进行了统计。对这种无丝分裂的细胞学特点,以及它在加速细胞分裂过程上的意义也进行了讨论。     

CONTINUOUS OBSERVATIONS OF AMITOSIS IN DEDIFFERENTIATING LIVING CELLS OF CARROT IN VITRO

Continuous observations of cleavage amitosis in dedifferentiating living cells of carrot were made in vitro. The cells observed were taken from root callus. They were first cultured to survive and then began to divide continuously, so that the whole process of cell division in the living body could be observed under phase contrast microscope. According to the cytological characteristics, the whole division process could be divided into four phases—prophase, metaphase, anaphase and telophase. Statistics of time necessary for each phase was made. In the present paper, the cytological characteristics of such amitosis as well as the significance of such amitosis in accelerating the course of division are discussed.     

COMPARATIVE OBSERVATION OF FIRST MITOSIS IN DIFFERENTIATION AND

On the basis of observing the continuous process of the first mitosis of normal differ-entiation in vivo and comparing this observed results with the process of the first mitosisof dedifferentiation in vitro in wheat pollen grains, the cytological differences between thetwo kinds of mitosis have been found. These differences are expressed chiefly by the posi-tions of nuclei and cytoplasm as well as the positions and shapes of spindles and new cellwalls. The author considers: (i) The differences exist as soon as cell division begins. Sothe critical moment causing cell dedifferentiation is at the interphase instead of the divisionstage. Therefore, the viewpoint that the cause of dedifferentiating initiation is the altera-tion of the direction of the spindle axis could not be agreed. (ii) The cause producing thesecytological differences can be related to the loss of polarity in the dedifferentiating process.     

玉米花粉植株的诱导及其后代的观察

本文报道了近两年来玉米花药培养研究中所取得的主要实验结果。接种花药时花粉发育时期对诱导频率影响很大,单核中期诱导率最高,一般为3—7％,个别可达15.6％,各发育时期的花粉对15％的蔗糖都产生较好的反应,在诱导培养基中加入适当配比浓度的激素(2,4-D2毫克/升和激动素1毫克/升)及一定浓度的酪朊水解物(500毫克/升)和活性炭(0.5％)能明显提高诱导频率。通过花药压片和切片的显微镜观察,已见到2-4个细胞的花粉粒和多细胞团,同时也发现部分花药的药壁或药隔细胞活化和增生而形成愈伤组织,植株根尖压片染色体数多为10,证明是来源于花粉的单倍体植株,单倍体植株移入土中,经加倍处理后于1977年4月有一株同时抽雄、吐丝,通过人工自交授粉,于6月1日收获一个有65粒种子的果穗,7月下旬播种出苗后,又对其后代进行了比较观察。     

风信子外植体直接再分化花芽的研究——Ⅰ.花芽和营养芽形态发生的控制

本文研究外源激素和外植体对风信子花芽和营养芽再分化的控制。其结果为:(1)对花瓣外植体来说,培养基中附加2,4-D只能诱导形成愈伤组织;附加6-BA能诱导营养芽;附加玉米素能诱导直接再分化花芽。(2)在附加玉米素的培养基上,花瓣和花茎外植体能直接再分化花芽;幼叶和鳞片只能诱导再分化营养芽。(3)在附加玉米素的培养基上,从花瓣外植体再分化的花芽上分离的花瓣可以继续再分化花芽;从花瓣外植体再分化的营养芽上分离的叶切段只能诱导再分化营养芽。结果表明,对于诱导风信子外植体直接再分化花芽来说,培养基中附加玉米素和外植体必须取自花器官是两个关键因素。