Study on Tissue Culture and Radiation Mutation of Astragalus membranaceus Bge. var. mongholicus(Bge.) Hsiao

[Objective] The research aimed to study the tissue culture technology and callus induction by radiation mutation of A. membranaceus Bge. [ Method ] With the different parts of Astragalus membranaceus Bge. var. mongholicus （ Bge. ） Hsiao aseptic seedling as explants （ leaves, cotyledons, hypocotyls） induced callus, and cotyledon and hypocotyls taken by the method of radiation mutation were studied. [ Result]The results showed that the three explants had relatively high callus induced rate in the medium which respectively made up of MS ＋6-BA 2.0 mg/L ＋ NAA2.0 mg/L, LS ＋6-BA2.0 mg/L ＋NAA0.1 mg/L, MS ＋ 6-BA2.0 rng/L ＋ NAA2.0 rag/L; the optimum mutation time of hypocotyls and cotyledons was 15 minutes; the growth of the callus induced from hypocotyls would be better as the mutation time increased, but when it reached a certain time the growth would be weaken, the induction rate also would be reduced. [ Conclusion] This study will provide the scientific reference in tissue culture and mutation breeding of A. membranaceus Bge.

MOLECULAR ANALYSIS OF RADIATION-INDUCED MUTATION IN EXON 7/8 OF RAT HPRT GENE

Objective To investigate the relationship between the radiation dose and the HPRT gene lo-cus mutation in rat smooth muscle cells, and provide the molecular basis for prevention of restenosis after percutaneous transluminal coronary angioplasty (PTC4). Methods The smooth muscle cells cultured in vitro were irradiated by radionuclide 188Re in different doses. HPRT gene mutation colonies were selected and isolatedby 6-thioguanine. Analysis of mutation in exon 7/8 of HPRT gene were accomplished by polymerase chain reaction and single-strand conformation polymorphism. Results The HPRT gene mutation frequency of rat smooth muscle cells that were irradiated by radionuclide 188Re ranged from 5.5× 10-6 to 13 ×10-6. Of 91 HPRT gene mutation colonies, 13 (14.3%) contained exon 7/8 deletion and 15(16.5%) had point mutation.The exon 7/8 mutation frequency was 30.8% . There were significant relationships between radiation dose and mutation frequency of HPRT gene and exon 7/8 . Conclusion The DNA damage and gene mutation inducedby radiation has positive relationship with radiation dose, and is a basis of proliferation inhibition and apopto-sis of smooth muscle cells.

Breeding Technology of eui-hybrids of Rice

Induced mutants of elongated uppermost internode (eui) were directly obtained after irradiation on maintainer (B) and restorer (R) lines of hybrid rice. CMS lines(A) with eui (referred to as eA), restorer lines with eui (referred to as eR) as well as hybrid rice with eui gene (referred to as e-hybrids)were developed. The results showed that the eui mutation frequency averaged 0.10‰ at a range of 0.02‰- 0.47‰ varying with applied dosage and mutated materials. Genetic diversities of eui stock, and a new eui gene, temporarily designated as eui2(t), was identified. eA lines have a significantly elongated uppermost internode causing better panicle exsertion and possessing higher outcrossing potential, e-hybrids increased plant height by 3 -10 cm and headed 2-3 days earlier, as well as showed greater grain weight resulting in higher yield potential than that of corresponding original hybrids. The technology systems without GA3, a few of using GA3 in hybrid rice seed production, and the establishment of e-hybrid rice breeding system were also discussed in this paper.

Nuclear Technique and Agriculture in China

Nuclear technique is a powerful scientific tool in agricultural research, an area with fruitful achievements in China. Application of nuclear technique in agriculture (Nuclear Agricultural Sciences) based on the development of related science and technology is a high-tech area, and also a significant aspect of non-electrical power application of nuclear technique. As an important component of agricultural science and technology, Nuclear technique application in agricultural field has achieved a lot and made remarkable contributions to the economic, social and ecological development of China. The current paper reviews the achievements, and presents the situation of the application of nuclear technique in the Chinese a-griculture briefly. The author strongly suggests that Chinese government should pay more attention to the study on the application of nuclear technique in agriculture, in order to promote its development and contribute more to the Chinese society and agriculture.