High-throughput screening system of citrus bacterial cankerassociated transcription factors and its application to the regulation of citrus canker resistance

One of the main diseases that adversely impacts the global citrus industry is citrus bacterial canker(CBC),caused by the bacteria Xanthomonas citri subsp.citri(Xcc).Response to CBC is a complex process,with both proteinDNA as well as protein–protein interactions for the regulatory network.To detect such interactions in CBC resistant regulation,a citrus high-throughput screening system with 203 CBC-inducible transcription factors(TFs),were developed.Screening the upstream regulators of target by yeast-one hybrid(Y1H)methods was also performed.A regulatory module of CBC resistance was identified based on this system.One TF(CsDOF5.8)was explored due to its interactions with the 1-kb promoter fragment of CsPrx25,a resistant gene of CBC involved in reactive oxygen species(ROS)homeostasis regulation.Electrophoretic mobility shift assay(EMSA),dual-LUC assays,as well as transient overexpression of CsDOF5.8,further validated the interactions and transcriptional regulation.The CsDOF5.8–CsPrx25 promoter interaction revealed a complex pathway that governs the regulation of CBC resistance via H2O2homeostasis.The high-throughput Y1H/Y2H screening system could be an efficient tool for studying regulatory pathways or network of CBC resistance regulation.In addition,it could highlight the potential of these candidate genes as targets for efforts to breed CBC-resistant citrus varieties.

Impact of multidrug resistance on the management of bacterial infections in cirrhosis

Patients with cirrhosis have an increased risk of infection and differently from other complications,that over the years are improving in their outcomes,infections in cirrhotic patients are still a major cause of hospitalization and death(up to 50%in-hospital mortality).Infections by multidrug-resistant organisms(MDRO)have become a major challenge in the management of cirrhotic patients with significant prognostic and cost-related impact.About one third of cirrhotic patients with bacterial infections is infected with MDR bacteria and their prevalence has increased in recent years.MDR infections have a worse prognosis compared to infections by non-resistant bacteria because they are associated with lower rate of infection resolution.An adequate management of cirrhotic patients with infections caused by MDR bacteria depends on the knowledge of some epidemiological aspects,such as the type of infection(spontaneous bacterial peritonitis,pneumonia,urinary tract infection and spontaneous bacteremia),bacteriological profile of antibiotic resistance at each health care unit and site of infection acquisition(community acquired,healthcare associated or nosocomial).Furthermore,regional variations in the prevalence of MDR infections determine that the choice of empirical antibiotic therapy must be adapted to the local microbiological epidemiology.Antibiotic treatment is the most effective measure to treat infections caused by MDRO.Therefore,optimizing antibiotic prescribing is critical to effectively treat these infections.Identification of risk factors for multidrug resistance is essential to define the best antibiotic treatment strategy in each case and the choice of an effective empirical antibiotic therapy and its early administration is cardinal to reduce mortality.On the other hand,the supply of new agents to treat these infections is very limited.Thus,specific protocols that include preventive measures must be implemented in order to limit the negative impact of this severe complication in cirrhotic patients.

Molecular Screening of Rice Cultivated in Benin for the Identification of Xanthomonas oryzae Pv. oryzae and Bacterial Leaf Blight Resistance Genes

One of the most devastating diseases of rice worldwide is bacterial blight (BLB) caused by Xanthomonas oryzae pv. Oryzae (Xoo). In Benin, Xoo was first described in 2013 on wild rice Oryzae longistaminata. So far, no study has been done on Beninese Xoo strains. We do not know whether the pathogen has already passed into the rice varieties grown, or if they are exposed to other bacteria. Whereas the use of resistant varieties, carrying resistance genes, is the only highly effective and environmentally friendly way to control this disease, no information is available on these Xoo resistance genes in rice varieties grown in Benin apart from the one we recently. This study aims to identify Beninese Xoo strains, causing BLB and screen rice varieties grown in Benin for the main resistance genes. Diseased rice leaves showing typical symptoms of fire blight collected from different rice fields in the three phytogeographic areas of Benin were analyzed by PCR for Xoo-specific sequence identification. Furthermore, seventy-five collected rice accessions were screened to identify xa5, Xa7, xa13, and Xa21 resistance genes to Xoo. The results reveal that Xanthomonas oryzae was identified in two fields in Banikouara and one in Malanville. On the other hand, Sphingomonas sp. has been identified in several other rice fields in Benin. Forty-seven of seventy-five rice accessions examined (62.66%) carried Xoo resistance genes with 3 (4%) and 40 (53.33%) of xa5 and Xa21 respectively. None of the accessions had either Xa7 or xa13 resistance genes. Three accessions possess both xa5 and Xa21 genes. Isogenic lines IRBB60 and IRBB21, supposed to be a positive control, presented a Xoo sensitivity allele. These results indicate that Xoo has moved from the wild rice variety to the cultivated variety in northern Benin and varietal improvement programs must be implemented with varieties having several resistance genes for the efficient response against a possible BLB pandemic in Benin.

Codominance Functional Marker of Bacterial Blight Resistance Gene Xa7 in Rice

[Objectives]A codominance functional marker of the broad-spectrum bacterial blight resistance gene,Xa7,of rice was identified for accurate detection,generation tracking,and differentiation between homozygous and hemizygous genotypes of the gene.[Methods]A potential functional marker containing four primers was designed using Premier 5 software and based on the differences on the sequences of Xa7,xa7,and allele-free genomes.The molecular distinctness of the marker in different materials was verified by PCR.Three crossbreed lines of Xa7 and their parents were inoculated with seven bacterial blight strains at the booting stage to examine the affected agronomic traits at maturation.[Results]The homozygous R084 of Xa7 could be amplified into a 91 bp band and the Nip free of allele with a 153 bp band,while the heterozygote Nip/R084,91 bp and 153 bp bands.The candidate codominance marker,Xa7fun,amplified fragments that matched the predicted target bands.No 91 bp fragment was amplified from 18 germplasms of varied types,indicating a lack of Xa7 in them.Whereas Ry1,Ry2 and Ry3 had a 91 bp band,suggesting the inclusion of homozygous Xa7.Under an elevated temperature,Huazhan responded to the seven bacterial blight pathogens as highly susceptible(HS),intermediate susceptible(MS),or susceptible(S);R084 to six of the seven pathogens(HNA1-4,FuJ,GDA2,GD1358,PX086,and YN24)as highly resistant(HR),intermediate resistant(MR)or resistant(R);Ry-1 to five pathogens(GDA2,HNA1-4,FuJ,GD1358,and YN24)as HR or MR;Ry-2 to five pathogens(GDA2,GD1358,HNA1-4,PXO86,and YN24)as HR or R;and Ry-3 to 6 pathogens(HNA1-4,FuJ,GDA2,GD1358,PXO86,and YN24)as HR or MR.Therefore,the infiltration of Xa7 in the improved crossbred lines RY-1,RY-2,and RY-3 significantly accentuated the blight resistance of Huazhan.[Conclusions]Homozygous or hemizygous Xa7 could be accurately differentiated by the currently identified codominance functional marker Xa7 fun.The Xa7 introgression did not significantly alter the critical agronomic traits in the hybridization from generation to generation and could be safely applied in breeding rice varieties with bacterial blight resistance.

Study of the Effect of Bacterial Resistance Monitoring in Clinical Microbiology Testing

Objective:To observe and analyze the effect of bacterial resistance monitoring in clinical microbiology testing.Methods:600 microbial specimens collected in our hospital in the past year(April 2021 to April 2022)were used as the test subjects of this study.The specimens were divided into Group A(control group)and Group B(research group),with 300 cases in each group.Group A consisted of blood culture specimens,while Group B consisted of sputum specimens.After the tests were completed,the rates of unfavorable and favorable results,bacterial species distribution,and bacterial drug resistance of the specimens in both groups were compared.Results:Among group A specimens,29 cases were positive(9.67%)and 271 cases were negative(90.33%);among group B specimens,99 cases were positive(33.00%)and 201 cases were negative(66.00%);the difference between the two groups of data was statistically significant(P<0.05).As for the distribution of the types of bacteria,there were 472 cases of Gram-negative bacteria and 128 cases of Gram-positive bacteria.Conclusion:Bacterial resistance monitoring is helpful in clinical microbiology testing.Through proper monitoring,bacterial resistance can be well understood.In this way,patients get to receive appropriate treatment measures and suitable antibacterial prescriptions,thereby improving the patient outcome.

Comparative Assessment of Genetic Diversity of Peanut (Arachis hypogaea L.)Genotypes with Various Levels of Resistance to Bacterial Wilt Through SSR and AFLP Analyses

Bacterial wilt （BW） caused by Ralstonia solanacearum is an important constraint to peanut （Arachis hypogaea L.） production in several Asian and African countries, and planting BW-resistant cultivars is the most feasible method for controlling the disease. Although several BW-resistant peanut germplasm accessions have been identified, the genetic diversity among these has not been properly investigated, which has impeded efficient utilization. In this study, the genetic relationships of 31 peanut genotypes with various levels of resistance to BW were assessed based on SSR and AFLP analyses. Twenty-nine of 78 SSR primers and 32 of 126 AFLP primer combinations employed in this study were polymorphic amongst the peanut genotypes tested. The SSR primers amplified 91 polymorphic loci in total with an average of 3.14 alleles per primer, and the AFLP primers amplified 72 polymorphic loci in total with an average of 2.25 alleles per primer. Four SSR primers （14H06, 7G02, 3A8, 16C6） and one AFLP primer （P1M62） were found to be most efficient in detecting diversity. The genetic distance between pairs of genotypes ranged from 0.12 to 0.94 with an average of 0.53 in the SSR data and from 0.06 to 0.57 with an average of 0.25 in the AFLP data. The SSR-based estimates of the genetic distance were generally larger than that based on the AFLP data. The genotypes belonging to subsp, fastigiata possessed wider diversity than that of subsp, hypogaea. The clustering of genotypes based on the SSR and AFLP data were similar but the SSR clustering was more consistent with morphological classification ofA. hypogaea. Optimum diverse genotypes of both subsp, hypogaea and subsp.fastigiata can be recommended based on this analysis for developing mapping populations and breeding for high yielding and resistant cultivars.

In vitro and in silico studies of salicylic acid on systemic induced resistance against bacterial leaf blight disease and enhancement of crop yield

Salicylic acid(SA)is an effective elicitor to promote plant defenses and growth.This study aimed to investigate rice(Oryza sativa L.)cv.Khao Dawk Mali 105 treated with salicylic acid(SA)-Ricemate as an enhanced plant protection mechanism against bacterial leaf blight(BLB)disease caused by Xanthomonas oryzae pv.oryzae(Xoo).Results indicated that the use of SA-Ricemate as a foliar spray at concentrations of more than 100 mg L^(-1)can reduce the severity of BLB disease by 71%.SA-Ricemate treatment also increased the hydrogen peroxide(H_(2)O_(2))content of rice leaf tissues over untreated samples by 39–61%.Malondialdehyde(MDA)in rice leaves treated with SA-Ricemate also showed an increase of 50–65%when comparing to non-treated samples.The differential development of these defense compounds was faster and distinct when the SA-Ricemate-treated rice was infected with Xoo,indicating plant-induced resistance.Besides,SA-Ricemate elicitor at a concentration of 50–250 mg L^(-1)was correlated with a substantial increase in the accumulation of total chlorophyll content at 2.53–2.73 mg g^(-1)of fresh weight which suggests that plant growth is activated by SA-Ricemate.The catalase-and aldehyde dehydrogenase-binding sites were searched for using the CASTp server,and the findings were compared to the template.Chemsketch was used to design and optimize SA,which was then docked to the catalase and aldehyde dehydrogenase-binding domains of the enzymes using the GOLD 3.0.1 Software.SA is shown in several docked conformations with the enzymes catalase and aldehyde dehydrogenase.All three catalase amino acids(GLN7,VAL27,and GLU38)were discovered to be involved in the creation of a strong hydrogen bond with SA when SA was present.In this mechanism,the aldehyde dehydrogenase amino acids LYS5,HIS6,and ASP2 were all implicated,and these amino acids created strong hydrogen bonds with SA.In field conditions,SA-Ricemate significantly reduced disease severity by 78%and the total grain yield was significantly increased which was an increase of plant height,tiller per hill,and panicle in three field trials during Aug–Nov 2017 and 2018.Therefore,SA-Ricemate can be used as an alternative elicitor on replacing harmful pesticides to control BLB disease with a high potential of increasing rice defenses,growth,and yield components.

OsBLS6.2:A rice bacterial leaf streak resistance gene identified by GWAS and RNA-seq

Bacterial leaf streak(BLS),caused by Xanthomonas oryzae pv.oryzicola(Xoc),is a bacterial disease affecting rice production in Asia and Africa,whose severity is expected to increase with climate change.Identification of new quantitative-trait loci(QTL)or resistance genes for BLS resistance is essential for developing resistant rice.A genome-wide association study to identify QTL associated with BLS resistance was conducted using phenotypic and genotypic data from 429 rice accessions.Of 47 QTL identified,45 were novel and two co-localized with previously reported QTL or genes conferring BLS resistance.qBLS6.2 on chromosome 6 explained the greatest phenotypic variation.Combined analysis of differential expression and annotations of predicted genes near qBLS6.2 based on haplotype and disease phenotype identified OsBLS6.2(LOC_Os06g02960)as a candidate gene for qBLS6.2.OsBLS6.2 knockout plants showed higher resistance to Xoc than wild-type plants.Many other candidate genes for resistance to Xoc were identified.

Marker-Assisted Pyramiding of Genes Conferring ResistanceAgainst Bacterial Blight and Blast Diseases into Indian RiceVariety MTU1010

Two major bacterial blight （BB） resistance genes （Xa21 and xa13） and a major gene for blastresistance （Pi54） were introgressed into an Indian rice variety MTU1010 through marker-assistedbackcross breeding. Improved Samba Mahsuri （possessing Xa21 and xa13） and NLR145 （possessingPi54） were used as donor parents. Marker-assisted backcrossing was continued till BC2 generationwherein PCR based functional markers specific for the resistance genes were used for foregroundselection and a set of parental polymorphic microsatellite markers were used for background selectionat each stage of backcrossing. Selected BC2F1 plants from both crosses, having the highest recoveriesof MTU1010 genome （90% and 92%, respectively）, were intercrossed to obtain intercross F1 （ICF1） plants,which were then selfed to generate 880 ICF2 plants possessing different combinations of the BB andblast resistance genes. Among the ICF2 plants, seven triple homozygous plants （xa13xa13Xa21Xa21Pi54Pi54）with recurrent parent genome recovery ranging from 82% to 92% were identified. All the seven ICF2plants showed high resistance against the bacterial blight disease with a lesion lengths of only 0.53–2.28 cm, 1%–5% disease leaf areas and disease scoring values of ‘1’ or ‘3’. The seven ICF2 plants wereselfed to generate ICF3, which were then screened for blast resistance, and all were observed to behighly resistant to the diseases. Several ICF3 lines possessing high level of resistance against BB andblast, coupled with yield, grain quality and plant type on par with MTU1010 were identified and advanced forfurther selection and evaluation.

Genetics and Improvement of Bacterial Blight Resistance of Hybrid Rice in China

Since 1980s, rice breeding for resistance to bacterial blight has been rapidly progressing in China. The gene Xa4 was mainly used in three-line indica hybrid and two-line hybrid rice. The disease has been ＇quiet＇ for 20 years in China, yet in recent years it has gradually emerged and been prevalent in fields planted with newly released rice varieties in the Changjiang River valley. Under the circumstances, scientists inevitably raised several questions： what causes the resurgence and what should we do next？ And/or is resistance breeding still one of the main objectives in rice improvement？ Which approach do we take on resistance breeding so that the resistance will be more durable, and the resistance gene will be used more efficiently？ A combined strategy involving traditional method, molecular marker-assisted selection, and transgenic technology should bring a new era to the bacterial blight resistance hybrid rice breeding program. This review also briefly discusses and deliberates on issues related to the broadening of bacterial blight resistance, and suitable utilization of resistance genes, alternate planting of available resistance genes; and understands the virulent populations of the bacterial pathogen in China even in Asia.

Application of Functional Markers to Identify Genes for Bacterial Blight Resistance in Oryza rufipogon

Field resistances of nine accessions of common wild rice （Oryza rufipogon Griff.） and one rice variety （IR24） were evaluated by using nine strains of bacterial blight pathogen （Xanthomonas oryzae pv. oryzae） from the Philippines. IR24 was highly susceptible to all the strains, and six common wild rice accessions resisted all the nine strains, with a resistance frequency of 67%. The accessions Yulin and Wanning were only susceptible to PXO280 and PXO71, respectively. The accession Gaozhou was susceptible to the three strains PXO79, PXO99 and PXO339, whereas resistant to the other six strains. It could be concluded that there is at least one resistance gene in each common wild rice accession. The functional markers of the genes xa5, xa13, Xa21 and Xa27 were used to detect the presence of these resistance genes in the nine tested wild rice accessions, and it was found that four wild rice accessions contained heterozygous xa13. Among the nine common wild rice accessions, five were homozygous for Xa27 and three homozygous for xa27, and the accession Laibin contained neither xa27 nor Xa27. In addition, there were no xa5 and Xa21 in all of these accessions.

Screening of Broad-spectrum Resistance Resources against Rice Bacterial Leaf Streak

[ Objectives] Rice materials with broad-spectrum resistance against several pathogenic strains of Xanthomans oryzae pv. Oryzicola （Xooc） at multiple growth stages were screened, in order to provide reliable resistance sources for variety breeding against rice bacterial leaf streak. [ Methods] A total of 1 100 rice lines with rich genetic background were offered as selective objects, and highly susceptible cultivar Jingang 30 was used as the control. Inoculation was carried out with five strong pathogenic strains of Xooc through acupuncture method at various growth stages for resistance identification. [ Results] Fourteen disease-resistant materials were obtained through preliminary screening, accounting for 1.27% of the total materials. Nine materials moderately resistant to bacterial leaf streak were obtained via secondary screening, accounting for 0.82% of the total materials. Besides, three of them （ RL6, RL9 and RLL4） were resistant to a number of pathogenic strains of Xooc at three growth stages. In particular, RL16 presented broad-spectrum resistance to multi-strains with high resistance levels. Six of them （ RI2, RIA, RIS, RL8, RL11 and RL12） were resistant to single strain at single growth stage. [ Conclusions] The obtained three materials have broad-spectrum resistance to bacterial leaf streak at multiple growth stages, which can be served as an important source to cultivate disease-resistant rice varieties. RL6 maintains high broad-spectrum resistance at all growth stages, which can be used as a prior resistance source for rice variety breeding. Six materials obtained with resistance against bacterial leaf streak at particular growth stages can be used as candidate resistance sources.

Transgenic Rice Plants Harboring Genomic DNA from Zizania latifolia Confer Bacterial Blight Resistance

Based on the sequence of a resistance gene analog FZ14 derived from Zizania latifolia （Griseb.）, a pair of specific PCR primers FZ14P1/FZ14P2was designed to isolate candidate disease resistance gene. The pooled-PCR approach was adopted using the primer pair to screen a genomic transformation-competent artificial chromosome （TAC） library derived from Z. latifolia. A positive TAC clone （ZR1） was obtained and confirmed by sequence analysis. The results indicated that ZR1 consisted of conserved motifs similar to P-loop （kinase la）, kinase 2, kinase 3a and GLPL （Gly-Leu-Pro-Leu）, suggesting that it could be a portion of NBS-LRR type of resistance gene. Using Agrobacterium-mediated transformation of Nipponbare mature embryo, a total of 48 independent transgenic To plants were obtained. Among them, 36 plants were highly resistant to the virulent bacterial blight strain PXO71. The results indicate that ZR1 contains at least one functional bacterial blight resistance gene.

Resistance Evaluation of Indica Rice Varieties with Bacterial Blight Resistance Genes Xa21 and Xa23 under Different Genetic Backgrounds

[Objectives]The paper was to evaluate the resistance of indica rice varieties with bacterial blight resistance genes Xa21 and Xa23 under different genetic backgrounds.[Methods]The rice materials with bacterial blight resistance genes Xa21 or Xa23 were used as the donors,and those without the genes were used as the receptors.By back crossing,composite crossing and other methods,combined with molecular marker-assisted selection(MAS),the materials with Xa21 or Xa23 gene,and their sister lines with/without Xa21 or Xa23 gene were inoculated with 7 widely used physiological races of Xanthomonas oryzae,and the resistance of the materials to bacterial blight was analyzed.[Results]The proportions of cumulative resistance(HR,R,MR)of rice materials with resistance gene Xa21 were HNA1-4/PXO86(84.62%)>YN24(82.14%)>GD1358(73.08%)>PXO99(67.86%)>GDA2(63.33%)>FuJ(6.67%),indicating that the materials with Xa21 gene had no resistance to bacterial blight induced by strain FuJ,but for other strains,there were still 36.67%-15.38%of the materials susceptible to the disease.The cumulative resistance(HR,R,MR)of the materials with Xa23 gene was over 76%,but there were still 23.02%-15.52%of the materials that had no resistance to the 7 strains.The analysis of variation coefficient of lesion length showed that the resistance of materials with Xa21 or Xa23 genes varied among strains,or the resistance to the same strain varied among materials.Correlation analysis demonstrated that there was significant or extremely significant positive correlation between strain GDA2 or HNA1-4 and other 6 corresponding strains in the materials with Xa21 gene,and there was extremely significant positive correlation between strain YN24,GD1358 or PXO86 and other 6 corresponding strains in the materials with Xa23 gene.Selection of these strains for resistance identification could improve the efficiency of breeding.Analysis of sister lines showed that bacterial blight resistance of Xa21 or Xa23 genes was related to the donor of the materials.Correlation analysis showed that the resistance of the materials with Xa21 gene had extremely significant positive correlation with parents(R=0.5725**),and the resistance of the materials with Xa23 gene had significant positive correlation with parents(R=0.2212*).[Conclusions]The study provides the reference for molecular resistance breeding of bacterial blight.

Resistance Evaluation of Dominant Varieties against Rice Blast (Magnaporthe oryzae) and Bacterial Blight (Xanthomonas oryzae pv. oryzae) in Guangzhou, China

The resistance of dominant rice varieties in Guangzhou against rice blast(Magnaporthe oryzae)and bacterial blight(Xanthomonas oryzae pv.oryzae)were evaluated by artificial inoculation and field natural blast nursery identification.Among 11 varieties tested,seven varieties showed resistance to rice blast,accounting for 63.6%;two varieties were highly resistant,accounting for 18.2%;three varieties were resistant,accounting for 27.3%;two varieties were moderately resistant,accounting for 18.2%;four varieties were susceptible(moderately susceptible),accounting for 36.4%.Varieties showed different resistance against the prevailing pathotype IV of bacterial blight;one variety was resistant,accounting for 9.1%;three varieties were moderately resistant,accounting for 27.3%;five varieties were moderately susceptible,accounting for 45.5%;one variety was susceptible,accounting for 9.1%;one variety was highly susceptible,accounting for 9.1%;all varieties tested showed susceptible to the virulent pathotype V.Huanghuazhan,Yuejingsimiao 2 and Fengxiuzhan showed resistance against both bacterial blight(pathotype IV)and rice blast,accounting for 27.3%.It is helpful to reduce the production risk by extending such dominant rice varieties with good resistance to rice blast and bacterial blight.

Screening of Effective Resistance Genes and Resistant Rice Parents against Rice Bacterial Blight(Xanthomonas oryzae pv. Oryzae) in Guangxi Province

[ Objective ] The paper was to confirm the resistance genes and resistant parents of rice against bacterial blight that could be used in Guangxi Province. [ Method] The dominant pathogenic types Ⅳ of Xanthomonas Oryzae pv. Oryzae in Guangxi were inoculated on a set of monogenic rice lines, the main hybrid rice parents in Guangxi and some important rice germplasm resources, and its resistant and susceptible conditions were investigated. [ Result ] IRBBS, IRBB7 and CBB23 were the resistant rice parents with resistance against pathogenic type IV, which contained resistance genes xa5, Xa7 and Xa23, respectively, and were identified to be the effective resistance genes against pathogenic type Ⅳ of X. Oryzae in Guangxi. [ Conclusion] The results provided basis for resistance breeding against bacterial blight.

Inheritance of resistance to bacterial streak and bacterial blight in rice

Bacterial streak (BS) caused by Xanthomonascampestris pv. oryzicola has become one of themajor diseases in southern rice areas. Up todate, there are few reports on the inheritanceof resistance to BS and its relationship with theresistance to bacterial blight (BB). Therefore,we analyzed the inheritance of resistant to BSin three resistant rice cultivars and the geneticrelationship of resistance between BS and BB.

Resistance of Antimicrobial Peptide Gene Transgenic Rice to Bacterial Blight

Antimicrobial peptide is a polypeptide with antimicrobial activity. Antimicrobial peptide genes Np3 and Np5 from Chinese shrimp （Fenneropenaeus Chinensis） were integrated into Oryza sativa L. subsp, japonica cv. Aichi ashahi by Agrobacterium mediated transformation system. PCR analysis showed that the positive ratios of Np3 and Np5 were 36% and 45% in To generation, respectively. RT-PCR analysis showed that the antimicrobial peptide genes were expressed in T1 generation, and there was no obvious difference in agronomic traits between transgenic plants and non-transgenic plants. Four Np3 and Np5 transgenic lines in T1 generation were inoculated with Xanthomonas oryzae pv. oryzae strain CR4, and all the four transgenic lines had significantly enhanced resistance to bacterial blight caused by the strain CR4. The Np5 transgenic lines also showed higher resistance to bacterial blight caused by strains JS97-2, Zhe 173 and OS-225. It is suggested that transgenic lines with Np5 gene might possess broad spectrum resistance to rice bacterial blight.

Effects of Bio-organic Fertilizer with Antagonistic Bacteria against Tobacco Bacterial Wilt on Soil Microbial Communities and Disease Resistance of Tobacco

In this study, the effects of bio-organic fertilizer with antagonistic bacteria against tobacco bacterial wilt on soil microbial communities and disease resist- ance of tobacco were investigated by field experiment. The results showed that the incidence of tobacco bacterial wilt in bio-organic fertilizer treatments （T3 and T4） decreased remarkably among four treatments in the field. Compared with the local conventional fertilization group, the incidence of tobacco bacterial wilt was re- duced by 21.9% and 25.0% in T3 and T4, respectively ; the yield of flue-cured tobacco was improved by 5.7% and 5.3%, respectively ; the proportion of mid- high grade tobacco leaves increased by 2.3% and 2.6%, respectively. After application of bio-organie fertilizer with antagonistic bacteria against tobacco bacterial wilt, rhizosphere soil microbial communities exhibited vast amount and abundant species ; the amount of rhizosphere soil bacteria of infected tobacco plants was im- proved by 218.5% with fewer species. It could be concluded that the application of bio-organic fertilizer with antagonistic bacteria against tobacco bacterial wilt could improve the ecological environment of tobacco field, inhibit the growth of pathogenic bacteria, decrease the incidence of tobacco bacterial wilt, and enhance the quality of flue-cured tobacco. This study laid the foundation for further ecological prevention and control of soil-borne diseases of tobacco.

Analyses of gene effects and inheritance of resistance to bacterial blight in rice

We analyzed the resistant inheritance of ajaponica variety,Jia23,to two bacterial blightpathogen strains,KS-6-6 and Zhe 173,rep-resenting respectively the two predominantpathogenic types(Ⅱ and Ⅳ)in the rice crop-ping area along the Yangtze River Valley.Jia23 was crossed with susceptible vari-eties,Ewan8 and 7416.Fplants were back-