| The organic development in vitro of bread wheat was studied in the present paper. The specific property on the development and differentiation of cells, tissues and organs in wheat were probed. Therefrom, the theoretical basis on selecting excellent genotypes of tissue culture response by means of trait correlation was provided, and the quantitative information on the way of organogensis in vitro in wheat was obtained, as well. Meanwhile, the developmental mechanism on heteromorphic floral organs was preliminary studied. The main results showed as following:1. In the three kinds of explants like mature embryos, immature inflorescences and immature embryos, the effect of in vitro from the immature embryos was best, while that of the immature inflorescences was equivalent to that of mature embryos. For instance: (1) The immature inflorescence fragments and their calli easily became ageing and browning. (2) The culture of mature embryo encountered more severe bacterium or mold growth due to the difficult sterilization in deep or internal layer, for that the contamination in many materials was over 50% , and the calli easily become dull, mashed, and poor quality. (3) The frequency of calli with leaf-like green spots of immature embryo culture was more high, reaching 13.86% in average, than that of mature embryo culture (1.33%) and that of immature inflorescence culture (0.00%) besides the frequency of total callus induction was closed to that of the mature embryo culture. (4)The mean frequencies of shoots or plantlets formed from the calli derived from immature embryos were at 38.73% and 55.31%, respectively, in the maintenance and differentiation culture. But those of mature embryos were only at 2.11% and 0.85%,respectively, clear to those of immature inflorescence at 2.13% and 0.00%. In addition, the calli from immature embryos could regenerate floral organs. The floral organs buds were morphologically incomplete with the appearance of unisexual pistillate flowers which were naked, exuberant white feather-like stigmas, but without stamens, paleas, lemmas and glumes. More various types of heteromorphic floral organs were produced from the calli from immature embryos of hybridizations between the material with high frequency of floral organ regeneration and the ditolosomic lines from 'Chinese Spring'. The heteromorphic floral organs were quite similar to the homeotic mutation in Antirrhinum and Arabidopsis. This was the first discovery in the immature embryo culture in wheat.2. The effect of plant growth regulators on immature embryo culture in wheat varied with the explants. In the mature embryo culture, the concentration of 2,4-D and the existence of KT had no significant influence on the frequency of total callus induction, but the comparatively low concentration (1.0 mg/1) of 2,4-D more promoted the development of calli with leaf-like green sports than 2.0mg/l. KT not only beneficial to heightening the fresh callus weight and frequency of embryonic callus, but also could obviously promote the calli developing organs. 6-BA supplemented in the differentiation medium was beneficial to developing the plants from the calli induced from immature embryos. However, KT and 6-BA resulted in the bad effects like slowing the dedifferentiation, browning the explants, lowering the frequency of callus induction, etc.3. The genotypes strongly influenced the efficiency of in vitro in wheat. In the culture of immature inflorescences in wheat, the rate of callus growth, the frequencies of root and shoot regenerations, browning resulted from thecytokines etc. were apparently different among the tested genotypes. Similarly, in the culture of immature embryo, the time of dedifferentiation, fresh callus weight, frequency of both the embryonic callus and the organogenesis including root and shoot were highly significantly different. The frequency of total callus induction originated from among the breeding lines existed more range than that of commercial cultivars. Consequentl...
|
PDF Full Text Request