Systemic acquired resistance, NPR1, and pathogenesis-related genes in wheat and barley

In Arabidopsis, systemic acquired resistance （SAR） is established beyond the initial infection by a pathogen or is directly induced by treatment with salicylic acid （SA） or its functional analogs, 2,6-dichloroisonicotinic acid （INA） and benzothiadiazole （BTH）. NPR1 protein is considered the master regulator of SAR in both SA signal sensing and transduction. In wheat （Triticum aesfivum） and barley （Hordeum vulgare）, both pathogen infection and BTH treatment can induce broad-spectrum resistance to various diseases, including powdery mildew, leaf rust, Fusarium head blight, etc. However, three different types of SAR-like responses including acquired resistance （AR）, systemic immunity （SI）, and BTH-induced resistance （BIR） seem to be achieved by activating different gene pathways. Recent research on wheat and barley NPR1 homologs in AR and SI has provided the initial clue for understanding the mechanism of SAR in these two plant species. In this review, the specific features ofAR, Si, and BIR in wheat and barley were summarized and compared with that of SAR in model plants of Arabidopsis and rice. Research updates on downstream genes of SAR, including pathogenesis-related （PR） and BTH-induced genes, were highlighted.

The Influence of Co-Suppressing Tomato 1-Aminocyclopropane-1-Carboxylic Acid OxidaseⅠon the Expression of Fruit Ripening-Related and Pathogenesis-Related Protein Genes

The purpose of this study is to explore the influence of co-suppressing tomato ACC oxidase Ⅰ on the expression of fruit ripening-related and pathogenesis-related protein genes, and on the biosynthesis of endogenous ethylene and storage ability of fruits. Specific fragments of several fruit ripening-related and pathogenesis-related protein genes from tomato （Lycopersicon esculentum） were cloned, such as the l-aminocyclopropane-1-carboxylic acid oxidase 1 gene （LeAC01）, 1- aminocyclopropane-l-carboxylic acid oxidase 3 gene （LeAC03）, EIN3-binding F-box 1 gene （LeEBF1）, pathogenesis-related protein 1 gene （LePR1）, pathogenesis-related protein 5 gene （LePR5）, and pathogenesis-related protein osmotin precursor gene （LeNP24） by PCR or RT-PCR. Then these specific DNA fragments were used as probes to hybridize with the total RNAs extracted from the wild type tomato Ailsa Craig （AC＋＋） and the LeAC01 co-suppression tomatoes （V1187 and T4B）, respectively. At the same time, ethylene production measurement and storage experiment of tomato fruits were carded out. The hybridization results indicated that the expression of fruit ripening-related genes such as LeACO3 and LeEBF1, and pathogenesis-related protein genes such as LePR1, LePR5, and LeNP24, were reduced sharply, and the ethylene production in the fruits, wounded leaves decreased and the storage time of ripening fruits was prolonged, when the expression of LeACO1 gene in the transgenic tomato was suppressed. In the co-suppression tomatoes, the expression of fruit ripening-related and pathogenesis-related protein genes were restrained at different degrees, the biosynthesis of endogenous ethylene decreased and the storage ability of tomato fruits increased.

Characterization of NPR1 Genes from Norton and Cabernet Sauvignon Grapevine

Non-expressor of pathogenesis-related genes 1 （NPR1） plays a significant role in the defense responses of plants to pathogens by regulating the expression of defense-related genes. In the present study, we isolated two NPR1 genes from Vitis aestivalis cv. Norton and Vitis vinifera cv. Cabernet Sauvignon, which were referred to as VaNPR1.1 and VvNPR1. 1-CS, respectively. They encode a protein of 584 amino acids with a predicted molecular weight of 64.8 kDa and a theoretical isoelectric point （pI） of 5.74. The predicted amino acid sequences of VaNPR1.1 and VvNPR1.1-CS differ by only one amino acid. Over-expression of VaNPR1.1 gene in Arabidopsis npr1-1 mutant plants restores the transcriptional expression of AtPR-1 gene, though not to the full scale. This result demonstrated that a grapevine VaNPR1.1 possesses a similar function to the Arabidopsis NPR1 in the regulation of defense-related genes. Over-expression of VaNPR1.1 in transgenic Arabidopsis plant increased tolerance to salinity, but had no effect on the drought tolerance. We conclude that VaNPR1.1 is a functional ortholog of AtNPR1 and also involved in grapevine＇s response to the salt stress.

Studies on Genetic Transformation of NPR1 Gene into Maize by Microprojectile Bombardment

[Objective] This study aimed to explore the conditions of transformation of maize by microprojectile bombardment. [Method] Immature embryo-derived callus of maize inbred line 7239 was used as explants to study the effects of shoot distance, helium pressure, vacuum and bombardment frequency on the transformation efficien- cy in the particle bombardment system of maize. [Result] Considering the transfor- mation efficiency, particle bombardment with 100 μg/P of golden particles, at a shoot distance of 9 cm from the target cells, under helium pressure of 1 350 psi and vac- uum 25 inHg, and bombarding twice could achieve relatively ideal results. After se- lection on media supplemented with different concentration of hygromycin, some re- generated plants were obtained. The results of PCR and Southern blotting analysis demonstrated that the NPR1 gene had been integrated into the genome of trans- genic maize plants, with an average transformation efficiency of 1.76%. [Conclusion] The study laid the foundation for the cultivation and breeding of excellent resistant varieties of maize.

Cloning of Broad-spectrum Anti-disease NPR1 Gene with RT-PCR and Construction of Its Protein Expression Vector

[Objective] It is to clone broad-spectrum anti-disease gene NPR1 and to construct its protein expression vector.[Method] First to extract total RNA of Arabidopsis thaliana and design relevant primers,and then the method of reverse transcription PCR was adopted to clone.With the method of enzyme digestion and ligation,this gene will be directed into protein expression vector.[Result] After relevant testing,NPR1 was inserted into vector pMXB10 to obtain pMXB10-NPR1 protein expression vector.[Conclusion] Protein expression vector including NPR1 was successfully constructed.

Identification and Evaluation of Insect and Disease Resistance in Transgenic Cry1Ab13-1 and NPR1 Maize

PCR detection,quantitative real-time PCR(q-RTPCR),outdoor insect resistance,and disease resistance identification were carried out for the detection of genetic stability and disease resistance through generations(T2,T3,and T4)in transgenic maize germplasms(S3002 and 349)containing the bivalent genes(insect resistance gene Cry1Ab13-1 and disease resistance gene NPR1)and their corresponding wild type.Results indicated that the target genes Cry1Ab13-1 and NPR1 were successfully transferred into both germplasms through tested generations;q-PCR confirmed the expression of Cry1Ab13-1 and NPR1 genes in roots,stems,and leaves of tested maize plants.In addition,S3002 and 349 bivalent gene-transformed lines exhibited resistance to large leaf spots and corn borer in the field evaluation compared to the wild type.Our study confirmed that Cry1Ab13-1 and NPR1 bivalent genes enhanced the resistance against maize borer and large leaf spot disease and can stably inherit.These findings could be exploited for improving other cultivated maize varieties.

Cloning and Analysis of Full-Length cDNA of PumNPR1 Gene from Pyrus ussuriensis Maxim

The purpose of this study is to find a new gene resource for the researches of molecular breeding of Rosaceae plants disease-resistance. Pyrus ussuriensis Maxim is used as a starting material to clone the full-length cDNA of NPR1（nonexpressor of pathogenesis- related genes 1） which is a key regulator in SA （salicylic acid）-mediated systemic acquired resistance （SAR） by homologous cloning and RACE techniques. The length of the cDNA sequence was 1 767 bp, the ORF was 1 761 bp, it coded 586 amino acids, pi=5.58, the relative molecular weight was 65.009 ku, contained 19 kinds of amino acids, and had full BTB/POZ and ANK domains. Compared the homology of NPR1 gene in GenBank database, the homology with Pyrus pyrifolia, Arabidopsis thaliana, Nicotiana tabacum, Lycopersicon esculentum, Oryza sativa, Helianthus annuus were 98%, 62%, 68%, 65%, 57%, 63%. The homology offunctional area were 99%, 78%, 82%, 79%, 74%, 77%. This NPR1 gene was considered as homologic gene of Pyrus ussuriensis Maxim and named PumNPR1.

GmSKP1,a Novel S-phase Kinase-associated Protein 1 in Glycine max,Enhancing Resistance Against Phytophthora sojae Infection

Phytophthora root and stem rot of soybean caused by Phytophthora sojae(P.sojae)is a devastating disease that affects soybean[Glycine max(L.)Merr.]all over the world.S-phase kinase-associated protein 1(SKP1)proteins are key members of the SKP1/Cullin/F-box protein(SCF)ubiquitin ligase complex and play diverse roles in plant biology.However,the role of SKP1 in soybean against the phytopathogenic oomycete P.sojae remains unclear.In this study,a novel member of the soybean SKP1 gene family,GmSKP1 which was significantly induced by P.sojae,was reported.The expression of GmSKP1 was simultaneously induced by methyl jasmonate(MeJA),salicylic acid(SA)and ethylene(ET),which might suggest an important role for GmSKP1 of plant in responses to hormone treatments.Functional analysis using GmSKP1 overexpression lines showed that GmSKP1 enhanced resistance to P.sojae in transgenic soybean plants.Further analyses showed that GmSKP1 interacted with a homeodomain-leucine zipper protein transcription factor(GmHDL56)and a WRKY transcription factor(GmWRKY31),which could positively regulate responses to P.sojae in soybean.Importantly,several pathogenesis-related(PR)genes were constitutively activated,including GmPR1a,GmPR2,GmPR3,GmPR4,GmPR5a and GmPR10,in GmSKP1-OE soybean plants.Taken together,these results suggested that GmSKP1 enhanced resistance to P.sojae in soybean,possibly by activating the defense-related PR genes.