水稻稻瘟病抗性基因研究综述

In this paPer，authors gave the review of research progress in rice blast resistance genes．Number of genes conferring rice blast，widely used resistant materials to blast and method of rice blast identification have been summaried in details．The strategies of rice blast resistance breeding are also discussed．     

Genetic Dissection, Marker-assisted Introgression, and Pyramiding of Agronomic Traits in Rice

Through the efforts of the International Rice Genome Sequencing Project, the whole genome sequence office has been decoded （International Rice Genome Sequencing Project, 2005）. This sequence information has provided new tools for genetics and has created a new paradigm of plant breeding. Many phenotypic traits of economic interest are controlled by multiple genes and often show complex and quantitative inheritance： Recent progress in rice genomics has had a great impact in the genetic dissection of such traits into single genetic factors. Such genetic factors can subsequently be identified at the molecular level by map-based strategies （Yano, 2001）. So far, we have identified several genes involved in heading date （Yano et al., 2001）, field resistance to rice blast, cool temperature tolerance （Takeuchi et al., 2001） and pre-harvest sprouting （Takeuchi et al., 2003）, and genetic dissection of root morphology and yield-related traits is progressing. Working from the current status of genetic dissection, we have begun marker-assisted introgression of particular genes of interest into elite rice cultivars in Japan. Exploitation of economically important genes in natural variants will be essential to enhance the potential of new breeding strategies.     

Identification of BPH Resistant Gene in Changseongbyeo

BPH （Brown planthopper, Nilaparvata lugens Stal） is a major insect of rice and give a lot of damages around Korea, Japan and East-West Asia. Especially, Increase of the environmentally friendly cultivation in South Korea has caused the outbreak of BPH rapidly. But few resistant varieties in Korea have known until now. Utilization of resistance（R） genes in breeding programs has been the most effective and economical strategy for controlling insect resistance. Now, It is reported that BPH-resistant genes is about eighteen （Suet al., 2003）. Especially, it has reported that Bphl gene is located on a long side of chromosome 12 and linked to bph2 （Sharma et al., 2004）. Bph3 is located on a short side of chromosome 4 （Sun et al., 2005）. But, because of no resistant germplasm to BPH in Japonica, it is very difficult to breed BPH-resistant variety with high grain quality.     

Gene Identification and Reaction of Rice Varieties to Korean and Philippine Races of Xanthomonas oryzae. pv. Oryzae

Bacterial blight （BB） caused by Xanthomonas oryzae pv. Oryzae （Xoo） is one of the most serious diseases of rice. Ten races of the bacterium have been identified in the Philippines. Each race has specific virulence to varieties with different resistance genes, showing a gene-for-gene relationship in the host-pathogen interaction （Lee et al., 2003）. So far, twenty-nine major genes have been identified （Lee et al., 1999）. Due to emergence of the new races and genetic vulnerability of resistant varieties, the spreading of bacterial blight disease occurrence is increasing now in all areas of Korea. This study was carried out to find the gene identification and reaction of rice varieties to Korean and Philippine races ofXanthomonas oryzae, pv. oryzae.     

Brown Planthopper Resistance Genes in Rice： from Germplasm to Breeding

The brown planthopper （BPH）, Nilaparvata lugens Stal （Homoptera： Delphacidae）, is one of the most destructive and widespread insect pests of rice （Oryza sativa） that can be found throughout the rice-growing areas in Asia, causing significant yield loss in susceptible cultivars every year. In addition to causing physiological damage to the rice plant, BPH also causes indirect damage by acting as a vector for rice ttmgro virus, grassy stunt virus and ragged stunt virus. Planting the resistant variety can efficiently restrain the breaking-out of BPH and its damage to rice. Mapping and cloning the BPH resistance genes will be propitious to the development of resistant rice variety and understanding of BPH-resistance mechanism in rice.     

Genetic Analysis of Rice Mutants Identifies a New Locus at the Pi-ta Region Controlling Pathogen Recognition

Understanding the molecular mechanisms of host and parasite interactions should facilitate the development of novel strategies to control plant diseases. Host interactions with biotrophic and hemi-biotrophic pathogens are known to follow a gene-for-gene specificity. The plant expresses a resistance （R） gene that is effective in preventing disease in response to pathogen races expressing the corresponding avirulence gene. We are studying the interaction mechanisms of the R gene, Pi-ta, in rice with the corresponding avirulence gene, A VR-Pita, found in the hemi-biotrophic pathogen, Magnaporthe oryzae （formerly Magnaporthe grisea）. Pi-ta is a putative cytoplasmic receptor with a centrally localized nucleotide-binding site and leucine rich domain at the carboxyl terminus （Bryan et al., 2000; Jia et al., 2000）. AVR-Pita is predicted to be a metalloprotease （Jia et al., 2006b）. The putative processed protein, AVR-Pita176, has been shown to interact with the Pi-ta protein （Bryan et al., 2000; Jia et al., 2000）.     

Development of Elongated Uppermost Intemode CMS Lines for Hybrid Rice Breeding in India

Development of cytoplasmic male sterile （CMS） lines with elongated uppermost internode （EUI） trait provides a genetic option to eliminate the use of GA3 in hybrid rice. During the past two decades, extensive work has been carried out on the subject that resulted in identification of several mutants with EUI trait for use in developing cytoplasmic/thermo-sensitive genic male-sterile lines with complete panicle exsertion （Okuno and Kawai, 1978; Rutger and Carnahan, 1981; Shen et al., 1987; Yang et al., 2000; 2002; Gangashetti et al., 2004）. Two recessive genes （eui-1 and eui-2） mapped on chromosome 5 and 10 respectively have so far been reported to control the internode elongation in rice （Librojo and Khush, 1986; Yang et al., 2001; Ma et al., 2004）. Considerable progress has been made in China in exploiting ＇eur gene for development of hybrid rice parental lines （Yang et al., 2000; 2002; Zhang et al., 2002）.     

Study on the Tolerance Mechanism of Alkaline Soil-Tolerant Wild Plants

The soil in many agricultural areas, including large parts of China, is becoming increasingly alkaline as a result of exploitation of soil resources. The soil becomes alkaline as a result of hydrolysis of two carbonates （Nail- CO3 and Na2CO3）. The pH of this soil is above 9.0, which seriously retards the growth of plants. We are interested in breeding transgenic plants that are tolerant of alkaline soil. We have identified several genes of rice that respond to carbonate stress and have found that over-expression of these genes improves carbonate stress tolerance （Liu et al., 2006a; Zhang et al., 2006; Liu et al., 2007; Yu et al., 2007）.     

Electrochemical behavior of gold and silver electrodeposited from thiourea leaching solution

Thiourea method can realize effective extraction and simplify the extraction process of gold and silverby utilizing thiourea solution as leaching agent and electrodepositing gold and silver from the thiourea leaching solution.Sulphuric acid solution containing Fe 3+5 g/Lthiourea(TU)50 g/L and pH=1 is used to leach goldsilver from pure goldpure silver and copper anode slim.The main thiourea complexes of silver and gold in the resulting leaching solution are ［Ag(TU)4］ +［Ag(TU)3］ +and ［Au(TU)2］ +.The cyclic voltammograms of thiourea leaching liquid shows that the initial reduction potential of Fe 3+H +［Au(TU)2］ +［Ag(TU)4］ +and ［Ag(TU)3］ +are 0.15V-0.25V-0.32V and -0.36V respectively.So gold is electrochemical reduced precipitation prior to silverthen reduced with silver togetherand in company with H +RSSR and other metallic impurities are reduced.However H2 evolution on cathode is the main reason for reducing the current efficiency.     

Drought Resistant Rice： an Integrated Crop Improvement Strategy

Rice physiological sensitivity to drought and its impact on crop productivity in water-limited environments are well-documented （O＇Toole, 2004）. However, rice yields in drought-prone rainfed lowlands and most upland areas remain low and the current challenges are to reduce yield gaps observed between experimental plots and farmers＇ fields, and to increase rice water productivity to economic levels （Bennett, 2003; Pandey et al., 2007）. The unpredictability of drought and its inherent complexity have made it difficult to characterize component traits required for improved performance, hindering the breeding efforts to enhance drought resistance.     

Interference elimination of PCB and its ramification in determining trace PBBs/PBDEs by GC/MS

The normal method to determine the trace brominated flame retardants such as polybrominated biphenyls (PBBs) and polybrominated diphenylethers (PBDEs) contained in the electronic and electrical products is gas chromatography/mass spectrometry (GC/MS). However, the method is based on the determinations of the persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs), and polychlorinated naphthalene (PCNs) etc. The interferences of those compounds are inevitable. Therefore, in order to overcome this problem, two methods e.g. 1) The combination use of gas chromatography negative ion chemical ionization mass spectrometry (GC-NICI-MS) and gas chromatography-electron impact-mass spectrometry (GC-EI-MS) is employed, 2) a matrix solid-phase dispersion (MSPD) method with YMC ODS-C18 as carrier is developed. The result show that, by the former method, the brominated isomers or ramifications are distinguished remarkably from other halogen compounds because that anion fragment retention peaks of ［Br］-, ［HBr2］- and molecule chain fragment retention peaks of ［M+2］+,［M+4］+,［M+6］+,［M+8］+ are observed simultaneously, and thus the selectivity to determine bromine-containing retardant flames is greatly improved. Using the latter method, the gas chromatographic peaks of multiple polychlorinated biphenyls and polybrominated diphenylethers can be efficiently separated. Thus provides a project to solve interferences of POPs in brominated flame retardants’ determinations. The standard addition experimental results of 10 kinds of BDEs/PCBs belonging to 8 sorts of electronic and electrical equipment show this method has a high precision and reliability due to 60%～98% recovery and <9.5% relative error, which meet the needs regulated by the IEC Commission. It provides a technical support for electronic and eletrical industries in China to further comply with RoHS directive.     

Salicylic Acid Induced Self-excision of the Marker Gene npt II Using CreloxP System from Transgenic Tobacco

Transgenic plants, despite a great deal of scientific evidences, have induced a number of environmental and consumer concerns for long time because various antibiotic resistance genes, according to common transformation strategies, will accompany engineered crops at all times. Several approaches, which have proven feasible, have been developed to excise marker genes from transgenic plants. The Cre-loxP site-specific recombination system from bacteriophage P1, which express the Cre protein to result in recombination between loxP sites, is one of the strategies mostly eliminated selectable marker in transgenic plants （Chen et al., 2003; Chen et al., 2004）. Either the transient expression or an inducible factor to turn on the expression of cre gene is existed in current Cre-loxP excision system. It requires crossing with a recombinase-expressing line and does not optimize to be functional for clonally propagated crops. Therefore, the strategies of self-excision of selectable markers mediated by CreloxP recombination system are coming to front （Cuellar et al., 2006; Mlynarova and Nap, 2003; Yuan et al., 2004; Zhang et al., 2006）.     

Fingerprinting Analysis of the Introgressed lines from Gossypium hirsutum L.× G.barbadense L.based on AFLP markers

The main cultivated varieties in the world belong to the species of upland cotton (Gossypium hirsutum L.),and their genetic background is very narrow.However,the wild species and races in the genus of Gossypium have abundant genetic diversity and possess lots of excellent genes with potential high yield,fine and strong fiber,disease and insect resistance,drought and coldness resistance,male sterility,and so on.     

Functional Analysis of DHS by Virus-induced Gene Silencing in Nicotiana benthamiana

With the progress in plant genomics research, the study direction is turned into the discovery and functional analysis of important genes. But an effective method is needed to investigate the biological function of eDNA sequences in large-scale （Wang et al., 2005）. With the newly developed technique-virus-induced gene silencing （VIGS）, plants infected with virus vector carrying host-derived sequence inserts will show loss-of-function or reduced-expression mutants in the host gene. The symptoms will tell the functional information of the gene （Liu et al., 2004; Burton et al., 2000）. Normally the process of constructing a virus vector and monitoring symptoms on infected plants can be completed within a few weeks, such that VIGS provides a simple, rapid and high throughput means of analyzing the function of sequenced genes.     

Recent Progresses in the Studies of Genetic Engineering for Cold Resistance in Plants

Low temperature is one of abiotic stresses limiting the geographical location suitable for growing corps and periodically account for significant losses in plant productivity, so it's important for agriculture to improve the cold resistance of corps. Many plants can acquire increased frost tolerance after a period of exposure to low, non-freezing temperature through a complex adaptive process called cold acclimation. In the past ten years, with the great advance in the researches of molecular mechanism of cold acclimation, the studies of genetic engineering for cold resistance in plants have also been carried out extensively. Currently, there are two kinds of genes used in plant cold-resistant genetic engineering, Which are protective genes and regulating genes. Many studies indicate both kinds of genes have good prospect for improving the cold resistance of plants. However, there are also many problems in this field to be solved immediately.     

Allelic Tests and Sequence Analysis of Three Genes for Resistance to Xanthomonas perforans Race T3 in Tomato

Three crosses,Hawaii7981×PI128216,Hawaii7981×LA1589,and PI128216×LA1589,were made to develop F_2 populations for testing allelism among three genes Xv3,Rx4,and Rx_(LA1589) conferring resistance to bacterial spot caused by Xanthomonas perforans race T3 in tomato. Each population consisted of 535–1 655 individuals. An infiltration method was used to inoculate the leaves of the parental and F_2 plants as well as the susceptible control OH88119 for detecting hypersensitive resistance(HR). The results showed that all the tomato plants except OH88119 had HR to race T3,indicating that Xv3,Rx4,and Rx_(LA1589) were allelic genes. Genomic DNA fragments of the Rx4 alleles from Hawaii7981,PI128216,and LA1589 were amplified using gene-specific primers and sequenced. No sequence variation was observed in the coding region of Rx4 in the three resistant lines. Based on the published map positions of these loci as well as the allelic tests and sequence data obtained in this study,we speculated that Xv3,Rx4,and Rx_(LA1589) were the same gene. The results will provide useful information for understanding the mechanism of resistance to race T3 and developing resistant tomato varieties.     

Molecurar Breeding for Resistant Varieties Against Asian Rice Gall Midge in China

Asian rice gall midge （GM） is a major rice pest in South China. Breeding resistance varieties has been a viable and ecologically acceptable approach for managing the pest. This paper reports that the progress of breeding resistant varieties using the markers linked to Gin6 against GM fxom the year 1998 to 2006 in China. The DNA fingerprints of 4 biotypes of GM population fxom 7 locations were analyses by AFLP. Base on the fine mapping of resistance gene Gin6 against all 4 Chinese GM biotypes by RAPD and SSR methods respectively, the STS markers and SSR markers linked to gene Gin6 were used for breeding through MAS. Some new resistant garplasm with Gin6 gene were created. And six cultivars and six two-line or one line three-line hybrid rice against GM were bred and extended to the farmer. The technique system of MAS for resistant varieties against Asian rice gall midge was set up at Guangdong province of China.     

Tentative Research About the Macroscopic Regulating to Blast

The paper analyzes the difference of the pathogenic varieties and the relationship of the variety composition,allording to the historic material to the varieties of the main hybid fece varieties in Southeast Sichuan during 1992 to 1998.It's the first time to advance to use the camparison on rate of pathogenic isolates between norm and refrieving to define the susceptible extent of the varity.It's an scientific base to adjust the structures of the vartieties,to reach the objective of the macroscopic regulating to rice blast.