A Microspore-derived Rice Transformation System and Dissection of the Complex RCg2 Promoter

Meaningful evaluation of promoter activity following dissection of various promoter elements requires the production of many transgenic rice plants. For such purposes, we have developed highly effective Agrobacteriummediated transformation systems. A recently-developed procedure utilizes microspore-derived calli and is capable of generating several hundred transformants per cocultivation event. Importantly, autodiploidization of transgenic haploid plants gives rise to homozygous plants in the first generation. We are currently determining if the autodiploidization frequency of -4% can be increased by exposing calli or young plantlets to colchicine. The promoter for RCg2, a gene encoding a putative lipid transfer factor, can drive strong expression of the GUS reporter in roots of transgenic rice （Xu et al., 1995）. However, it is very susceptible to silencing, reducing its potential value for biotechnological applications （Hall et al., 2001）. In silico analysis of the promoter revealed several putative down-regulating elements, including one centered on a region corresponding to a conserved element of the miniature inverted repeat transposable element （MITE） Janus （Yang and Hall, 2001; Yang and Hall, 2003）. Excision of various motifs from the RCg2 promoter revealed both positive and negative effects on promoter strength and frequency of silencing.     

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.     

Recovering Portuguese Rice Landraces by Marker-Assisted Selection

Rice （Oryza sativa L.） was domesticated in Asia and brought to Europe （Mediterranean region） by returning members of Alexander the Great＇s expedition to India （324 B.C） （Khush, 1997）. In Portugal, rice was introduced by the Moors in the 10th century, and therefore has a long cultural tradition. Among the European countries, Portugal has the highest rice consumption per capita, with approximately 22.4 kg/capita/year, while the second country, Spain, only consumes 10.4 kg/capita/year （data from http：//www.fao.org referring 2004）. In 2005, the total rice area harvested was 23 060 hm2, distributed on the four main river beds： Mondego, Tejo, Sado and Sorraia. Presently Portugal produces nearly 56% of the internal demands, to meet the national needs, importation reached 6.8 xl07 kg in the year 2005 （data from http：//ania.pt）. About 80 percent of the rice area in Portugal is cultivated with japonica varieties and the rest is cultivated with indica-like varieties. These indica-like varieties are being cultivated particularly in the Southern regions, with much acceptance by the farmers due to their higher yields. Presently all Portuguese commercial varieties are either from Italy or from overseas.     

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.     

Genetic Analysis and Molecular Mapping of a Novel Chlorophyll-Deficit Mutant Gene in Rice

A rice etiolation mutant 824ys featured with chlorophyll deficiency was identified from a normal green rice variety 824B.It showed whole green-yellow plant from the seedling stage,reduced number of tillers and longer growth duration.The contents of chlorophyll,chlorophyll a,chlorophyll b and net photosynthetic rate in leaves of the mutant obviously decreased,as well as the number of spikelets per panicle,seed setting rate and 1000-grain weight compared with its wild-type parent.Genetic analyses on F1 and F2 generetions of 824ys crossed with three normal green varieties showed that the chlorophyll-deficit mutant character was controlled by a pair of recessive nuclear gene.Genetic mapping of the mutant gene was conducted by using microsatellite markers and F2 mapping population of 495R/824ys,and the mutant gene of 824ys was mapped on the shon arm of rice chromosome 3.The genetic distances from the target gene to the markers RM218,RM282 and RM6959 were 25.6 cM,5.2 cM and 21.8 cM,respectively.It was considered to be a now chlorophyll-deficit mutant gene and tentatively named as chl11(t).     

RiceDB： A Web-Based Integrated Database for Annotating Rice Microarray

RiceDB, a web-based integrated database to annotate rice microarray in various biological contexts was developed. It is composed of eight modules. RiceMap module archives the process of Affymetrix probe sets mapping to different databases about rice, and aims to the genes represented by a microarray set by retrieving annotation information via the identifier or accession number of every database; RiceGO module indicates the association between a microarray set and gene ontology (GO) categories; RiceKO module is used to annotate a microarray set based on the KEGG biochemical pathways; RiceDO module indicates the information of domain associated with a microarray set; RiceUP module is used to obtain promoter sequences for all genes represented by a microarray set; RiceMR module lists potential microRNA which regulated the genes represented by a microarray set; RiceCD and RiceGF are used to annotate the genes represented by a microarray set in the context of chromosome distribution and rice paralogous family distribution. The results of automatic annotation are mostly consistent with manual annotation. Biological interpretation of the microarray data is quickened by the help of RiceDB.     

Analysis on the combination ability and stability of rice restore line Yihui1577

Yihui1577 was bred after over 10 generations by crossing R16 and Yunnan purple rice.Many new hybrid rice varieties had been bred with Yihui1577,of which Gangyou1577,Ⅱyou1577,Nyou1577 and Yixiang1577 were certified by Sichuan Province Crop Variety Release Committee,Gangyou1577 and Yixiang1577 were certified by National Crop Variety Release Committee.The series varieties bred with Yihui1577 had been used widely with accumulated areas of 1 200 000 hm2.By using Yihui1577 as breeding material,an excellent restore line Yihui 3003 and some other restore lines,such as Yihui1979,Yihui 315 with good rice quality and good combination ability had been bred.Analysis of combination ability and stability about restore line Yihui1577 was made by using agricultural experimentation and statistical approach.The combination ability analysis was made in complete dual crossing method with 4 CMS lines and 6 restorer lines.It showed that the general combination ability effect value of Yihui1577 was 0.226,while Minghui63 was-0.113.So the general combination ability of Yihui1577 was prior to that of Minghui 63.Stability analysis showed that the F value of Gangyou1577 was 1.81378,while Sanyou 63 was 1.40327,both didn't reach significant level.So Gangyou1577 had the same stability as Sanyou63.The same conclusion had got in the stability analysis of the breeds ofⅡyou 1577,Yixiang1577,Nyou 1577 and so on.     

稻田的甲烷释放量与收成有关

<正> 稻子是世界将近一半人口的主要农作物。遗憾的是,稻田潮湿土壤的缺氧环境非常适合制造甲烷的微生物,就产生温室效应而言,甲烷的作用仅次于二氧化碳。稻米的产量将随着世界人口的持续增长而增加,从而带来更多甲烷。不过,新的研究结果显示,最大限度地增加作物产量不仅可以