Guan Chunyun

Advances in normalized cDNA library and its applications.

The cDNA library normalized by reassociation is a newly-developed and effective platform for EST acquisition and gene discovery.It decreases the prevalence of clones representing abundant transcripts and dramatically increases the efficiency of random sequencing and rare gene discovery.The principle,procedure and applications of normalized cDNA library were reviewed in this paper,which provides theoretical basis for the development of normalized cDNA library and discover more novel genes.

Cloning and characterization of six oleic acid desaturase pseudogenes of Brassica napus.

The phenomenon of multi-copy genes is common in plants. Pseudogene is defined as an inactive gene, which can not synthesize functional proteins but share the similar DNA sequences with normal functional genes. In this study, 56 FAD2 DNA clones and 47 FAD2 seed cDNA clones of Brassica napus cv. Xiangyou 15 were investigated, and six new copies of FAD2 were detected, designated as FAD2P1-6 respectively. This sequence length of six copies ranged from 1141-1157 bp and there were no introns in their open reading frames (ORF). These six copies share 96.1% identity in nucleotides from one another, and share more than 87% nucleotides identity with AY577313. Deduced amino acid sequences revealed that 1–12 stop codons occurred in the coding region of six copies which will prevent them from coding for a functional protein. These six copies were investigated in vivo in Saccharomyces cerevisiae through being cloned into yeast expression vector pYES2.0, and the 16: 2 and 18: 2 fatty acids were determined by gas chromatographic analysis. The results revealed that the products of the six copies were not able to synthesize 16: 2 and 18: 2 fatty acids, suggesting that they are pseudogenes of FAD2. These multiple pseudogenes of FAD2 within the B. napus genome might result from the duplication of large chromosomal segments simultaneously following mutation. Because of the existence of multiple pseudogenes for FAD2 in B. napus genome, we should be careful in genetic research to identify true and false, to avoid wrong conclusions.

Absorption, Distribution, and Translocation of Nitrogen at Growth Stages in Oilseed Rape Plant

The differences of concentration and distribution of nitrogen in crop depend on organs and growth stages, and nitrogen redistribution in different organs will be occurred at different stages; these differences are related to the transfer of growth center. Consequently, the high crop yield depends not only on the high amount of nitrogen absorption, but also on the high efficiency of nitrogen redistribution. The objective of this study was to reveal the law of nitrogen absorption, distribution, and translocation in oilseed rape plant at different growth stages using two winter oilseed rape cultivars with the 15N labeling method in sand culture under Hoagland complete nutrient solution conditions. The results (average value from the two cultivars) indicated that 83.5% of nitrogen absorbed at the seedling stage, and 67.3% of nitrogen absorbed at the stem elongation stage, were distributed to leaves; 79.1% of the nitrogen absorbed at flowering stage was contained in leaves and stems, with 42.8% of it in the leaves. However, 42% of the nitrogen absorbed at siliquing stage was distributed to siliquae which is just the organ directly distributed the highest proportion of nitrogen absorbed at this stage. The nitrogen absorbed at four growth stages (seedling, stem elongation, flowering, and siliquing) translocated from the vegetative to the reproductive organs at 34.4%, 44.3%, 41.2%, and 31.7%, i.e. 203.2, 325.8, 218.0, and 82.0 mg plant-1, respectively. The translocated nitrogen from vegetative organs to the total nitrogen in seed accounted for 65.1%; among with 25.8% absorbed at the stem elongation stage, 16.9% absorbed at flowering stage, 15.9% absorbed at seedling stage, and 6.4% absorbed at siliquing stage, respectively. The proportion of nitrogen loss, after being absorbed at the four growth stages, was 24.0%, 10.5%, 11.7%, and 7.3 %, i.e. 141.6, 79.2, 43.2, and 16.2 mg plant-1, respectively. To sum up, nitrogen absorbed by roots at the earlier growth stages in oilseed rape was mainly translocated to leaves first, and then to the reproductive organ at the later growth stages.

The Current Carbon Sink Structure of China’s Staple Crop Production and Its Optimization Approach

The global warming caused by heavy emissions of greenhouse gases has posed a great threat to the existence and develop- ment of mankind. The carbon sink function of crops has an important regulating effect on climate changes. Actually the production of crops can be seen as the carbon source as well as the carbon sink. In this article, the authors gather and analyze the relevant carbon emission parameters of the staple crop production system in China, estimate the carbon sink effect of farmland and its dynamic change feature and quantitatively evaluate the carbon input and output of these crop production systems. In this way, the paper provides a basis for making the low-carbon agriculture planning and policies and proposes the approach to optimizing the carbon sink structure of the

Study on the Carbon Sink Function of Crop Production in Typical Agricultural Areas of China

China is a big agricultural country. The research on the carbon sink function of crop production in China’s typical agricultural areas plays an important role in estimating the regional carbon budget and making management policies to tackle climate changing issue. The production of staple crops can be generally reflected by their carbon sinks. The carbon sinks of different crops in the same area differ greatly, and the carbon sink of the same crop also differs in different areas. The national annual reserve of soil organic carbon can be generally embodied in its carbon sink as well. The annual reserves of soil organic carbon in different areas range between –2.07 TgC·y and 19.95 TgC·y.

Analysis on Uniformity of Seeding Based on Photoelectronic Detection Principle

For problems existing in seed-metering device uniformity testing, use photoelectric detection technology on seeding uniformity testing. Its working principle is to use optical sensors to monitor the situation that seeds passing through the seed channel, records the cumulative number of seeds of each channel by counting chips and MCU and periodically send to the PC, obtaining relevant data such as seeding uniformity of seed-metering device through further data analysis. Tests showed that under the same conditions, relative error between test data of the system and manual measured data is less than 5%, meet the actual needs. At the same time, compared to manual measurement, the system also has advantages of low cost, easy operation, without calculation and continuous online work available.

Effects of planting densities and fertilizer application levels on the main quality of Xiangzayou763

Field plot experiment was carried out on Xiangzayou763 to study the effects of different fertilizer application levels (N∶P2O5∶K2O∶B,treatment A,240∶120∶210∶1.2 kg/hm2;treatment B,180∶90∶157.5∶0.9 kg/hm2; treatment C,120∶60∶105∶0.6 kg/hm2; treatment D:60∶30∶52.5∶0.3 kg/hm2; treatment E, no fertilizer) and different planting densities (7.5×104, 1.5×105, 2.25×105, 3.0×105, 3.75×105, 4.5×105 plant/hm2) on oil content, protein content, thioglycoside content and erucic acid content in seeds. The results showed that oil content and protein content in seeds were greatly influenced by fertilizer application levels but less influenced by planting densities. Oil content of treatment C and D were much higher, protein content was increased with fertilizer application level increasing. Effects of fertilizer application level on oil content and protein content were higher than that of planting densities and the same trend was observed in seeds yield changes. The highest oil content and protein content were shown in fertilizer application treatment A with 2.25×105 plant/hm2 planting density. There was no regular change of thioglycoside content and erucic acid content in seeds under different fertilizer application levels and planting densities.

Interlocking RAPD marks of glucosinolate trait in Brassica napus.

In order to find intelocking RAPD marks for the glucosinolate trait in Brassica napus,967H and 967L were used as materials,which kept similar characteristics in quality and other agronomic traits except for the glucosinolate trait,to study RAPD marks of the parents and their F1 and F2 plants.The results showed that 6 RAPD primers from 482 RAPD primers were detected polymorphism between parents,and one RAPD primer(S268) from the 6 RAPD primers was detected polymorphism between two parents and two DNA bulks.The primer S268 could only display three kinds of different marks.Variant analysis with a single mark indicated that the low glucosinolate traits of 29.51% were contributed by the S268 mark.

Effect of different NPK ratio on yield and nutrient absorption of rapeseed variety Xiangzayou763

Field experiments were conducted to investigate the effects of different NPK ratio on yield and NPK uptake of Xiangzayou 763.The results showed that under the same amount of other fertilizers either with the higher nitrogen ratio or higher phosphorus ratio treatments a higher rapeseed yield could be obtained while the proportion of potassium application had no regular consensus under the same amount of other fertilizers.The accumulative amount of NPK in plant were correspondingly increased as the proportion of nitrogen and phosphorus fertilizer increased,while the accumulation of K as that;The tendency of NPK fertilizer utilization rates were all decreased with the increasing usage of the same kind of fertilizer,the sharpest decline appeared in the utilization of potassium,the smallest reduction appeared in nitrogen utilization.Among the twelve kind of tested NPK ratio,the highest rapeseed yield appeared in the proportion of N:P2O5:K2O=1:0.5:0.58,which reached 1 830 kg/hm2,followed by the N:P2O5:K2O = 1:0.5:0.88,which reached 1 800 kg/hm2,the lowest rapeseed yield appeared in N:P2O5:K2O = 1:0.4:1.4,which was only 1 350 kg/hm2.

Effects of Phosphorus on Growth and Uptake of Heavy Metals in Plants Grown in the Soil Contaminated by Uranium Tailing

The uranium tailing contains uranium and other heavy metals,such as lead,cadmium and zinc,which usually makes the surrounding soil and water bodies seriously polluted with contaminated rain and dust.There is a potential threat to humans health because the heavy metals can be absorbed and accumulated by the crops grown in the polluted areas,and then possibly transferred to human body by an environment-crop-food chain.The development of an economical and effective remediation method for the heavy-metal contaminated soil is urgent to improve environmental quality and enhance the food safety.As one of the fast-developing technologies,chemical stabilization has been widely studied,and the study on inhibition of heavy metal contamination by adding phosphorus-containing material to soil is becoming an international hotspot.In this study,two species of oilseed rapes,B.junea and B.napus,grown in containers with the uranium-tailing contaminated soil,were used to investigate the effects of phosphorus fertilization on plant growth and accumulation of heavy metals (U,Cd,Zn,and Pb).Container soil was treated by adding a phosphorus fertilizer NaH2PO4 with a rate of 0,30,60,120,240,and 480 mg P kg-1,respectively.For the control soil (without adding phosphorus fertilization),there were a lower concentration of total nitrogen,phosphorus,potassium,and organic matter,and a higher concentration of U,Cd,Zn,and Pb.Plant growth of both species was inhibited.Compared with the control group,the concentration of phosphorus significantly increased in plants grown in the P-fertilizer added soil.The DTPA-exactable concentrations of U,Cd,Zn,and Pb in this soil were decreased by 17.1-70.5%,24.0-57.6%,8.9-32.4%,and 8.6-55.8%,respectively.Also,addition of phosphorus in the uranium-tailing contaminated soil significantly decreased the contents of U,Cd,Zn,and Pb in plant organs.A significant positive correlation (P0.01) was observed between the contents of U,Cd,Zn,and Pb in plant organs of both species and DTPA-exactable concentrations of these metals in the contaminated soil.Additionally,addition of phosphorus fertilization of 60-480 mg P kg-1 significantly increased dry weight,height,root length and chlorophyll content of plants.A significant decrease of SOD activity and MDA content occurred in both species grown in the P-fertilizer treated soil compared to the control.Therefore,application of phosphorus fertilizer to the uranium-tailing contaminated soil is a practical and effective approach to reduce accumulation of heavy metals in plant organs of oilseed rapes and the risk of these pol-lutants entering the food chain.