Biological Effects of Low Energy N^+ Beams Implantation on Calluses of Autotetraploid Rice

Calluses of two autotetraploid rice （DPR （4） and Zijing （4）） were implanted with 30 KeV N＋beams at doses ranging from 1.0×1015 to 9.0×1015 ions cm-2. The differentiation rates of calluses, the concentration of malondialdehyde （MDA）, the activities of superoxide dismutase （SOD）, catalase （CAT） and peroxidase （POD）, and the change of esterase （EST） spectrum were measured and analyzed on the calluses stage. The results showed that differentiation rates of calluses under 3.0×1015 ions cm-2 （（46.12±2.01）%） were higher than the other treatment groups in DPR （4）, and those of Zijing （4） were similar under the doses of 1.0×1015, 3.0×1015 and 5.0×1015 ions cm-2 （（40.55±2.74）, （37.77±3.04） and （34.56±2.65）%） and were higher than that of 7.0×1015 and 9.0×1015 ions cm-2. When the doses were 3.0×1015 and 5.0×1015 ions cm-2, the activities of SOD, POD and CAT were notably enhanced, and the accumulation of MDA content was markedly alleviated in the implanted calluses of two materials, as well as the activity of EST was increased by the additional isforms DPR （4）. Whereas the anti-oxidative systems and enzymes spectrum of EST were destroyed seriously, the accumulation of MDA was signiifcantly aggravated, also the differentiation rate of calluses reduced sharply and almost closed to zero when the implantation doses were 7.0×1015 and 9.0×1015 ions cm-2. It suggested that the proper dose of ion implantation effectively maintained the normal membrane structure and metabolism, and it would be also a feasible approach for autotetraploid rice to improve its genetic characteristics at calluses stage. Additionally, the differences of the radiation resistance between DPR （4） and Zijing （4） could be related to the different genotypes.

Research on the Distant Hybrids of Wheat Obtained via Low-Energy Ion-Beam Implantation

The whole DNA of soybean was implanted into four varieties of wheat of Zhongyu 5, Huaiyin 9628, Wenyou 1, Jimai 5 respectively via ion-beam mediation. There were 5 plants obtained whose protein content was higher than 18.5 %, the highest one was 21.44 %. There were 3 plants obtained whose protein content was lower than 11.5%, the lowest one was 10.96%. We can see that the whole DNA of soybean transformed into wheat via ion beam implantation can induce the increase in wheat protein content dramatically. The result also shows that the transformation efficiency of different gene types of wheat receptor varies greatly that the implanting time has a certain effect on the efficiency of transformation.

Study of Biological Effects of Low Energy Ion Implantation on Tomato and Radish Breeding

Biological effects of 30 keV low energy nitrogen ion implantation on the seeds of five types of tomato and one type of radish were investigated. Results showed that low energy ions have different effects on different vegetables. The whole dose-response curve of the germination ratio did not take on ＂the shape of saddle＂, but was a rising and falling waveform with the increase or decrease in ion implantation. In the vegetable of Solanaceae, two outstanding aberrant plants were selected from M1 of Henan No.4 tomato at a dose of 7x 1017 nitrogen ions/cm2, which had thin-leaves, long-petal and nipple tip fruit stably inherited to Mr. Furthermore the analysis of the isozyme showed that the activity of the mutant tomato seedling was distinct in quantity and color. In Raphanus sativus L., the aberrances were obvious in the mutant of radish 791 at a dose of 5×10^17 nitrogen ions/cm^2, and the weight of succulent root and the volume of growth were over twice the control＇s. At present, many species for breeding have been identified in the field and only stable species have been selected for the experiment of production. It is evident that the low energy ion implantation technology has clear effects on vegetables＇ genetic improvement.

Differential Expression of Retrotransposon WIS 2-1A Response to Vacuum, Low-Energy N^+ Implantation and ^(60)Coγ-ray Irradiation in Wheat

Mutagenesis and retrotransposons have a close relationship, but little attention has been paid yet to the activity of retrotransposons produced by physical mutagens. The variation of retrotransposon WIS 2-1A activity in wheat （Triticum aestivum L.） embryos at three different growth times （30 h, 45 h and 60 h） was investigated after they had been treated with N^＋ implantation in a vacuum of 5× 10^-2 Pa and irradiation by ^60Coγ-ray respectively. For each of the three growth times the expression of WIS 2-1A showed almost entirely a same trend of downregulation, upregulation, then downregulation, and upregulation again with the increase in dose of N^＋ implantation, but the expression appeared irregular with the increase in irradiation of ^60Coγ-ray. In conclusion, the acutely activating effect of WIS 2-1A stimulated by vacuum and high dose N^＋ implantation within a shorter incubation time may provide a convenient tool to advance the research on mutagenic breeding and function genes.

A Preliminary Study on a Specifically Expressed Arabidopsis Promoter in Vascular Bundle

From a population of about 3500 single plants in Arabidopsis promoter trapping bank, one plant whose GUS-gene had been specifically expressed in vascular bundle, was screened by the method of gus tissue staining. The T-DNA flanking sequence was amplified using TAIL-PCR. This band will be purified and connected to TA cloning vector. After sequencing and searching in the genebank, its function will be demonatrated through transformation.