عنوان

Nucleotide sequence diversity in maize and grass-infecting streak geminiviruses:

Number

TLpq304392744

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

Nucleotide sequence diversity in maize and grass-infecting streak geminiviruses:

General Material Designation

[Thesis]

First Statement of Responsibility

P. Ngwira

Title Proper by Another Author

A basis for nucleotide sequence classification and identification

Subsequent Statement of Responsibility

D. T. B. Gordon, David M.

Name of Publisher, Distributor, etc.

The Ohio State University

Date of Publication, Distribution, etc.

1997

Specific Material Designation and Extent of Item

158

Dissertation or thesis details and type of degree

Ph.D.

Body granting the degree

The Ohio State University

Text preceding or following the note

1997

Text of Note

The genomes of seven maize streak geminivirus (MSV) isolates from maize (Zea mays) in Kenya, Malawi, Nigeria and Zimbabwe and Setaria verticillata in Kenya were cloned and characterized to define an MSV signature sequence and relate sequence and virulence characteristics. Restriction endonuclease analysis confirmed the MSV identity of the isolates. Multimeric clones were infectious when inoculated to maize by vascular puncture inoculation. Clones incited mild, moderate or severe symptoms. Mild and moderate symptom clones were obtained from severe isolates and a severe symptom clone from a mild symptom isolate. The nucleotide sequences of the large intergenic regions (LIR) and the coat protein (CP) genes of the clones were determined. Alignments of the LIR nucleotide and CP predicted amino acid sequences with those published for MSV-K, MSV-N and MSV-S showed LIR sequence identities were more variable (80.1-99.4%) than those of the CP amino acid sequences (95.5-99.2%). A dendogram of the LIR sequences clustered mild and moderate clones separately from severe clones which clustered into two groups. Neither mild, moderate nor severe clones were associated with unique LIR nucleotide sequences that would permit identification of symptom phenotype by specific LIR sequences. The previously identified iteron sequence, GCGCCTTC, was conserved among the clones. A second iteron sequence, TCTAAAG, conserved among the clones, was also present in the published LIR sequences of Panicum streak and sugarcane streak geminiviruses. Fully sequenced infectious mild and severe symptom clones were 2683 nucleotides in length and contained six potential ORFs, three in the viral (+) sense strand (V1-V3) and three in the complementary (-) sense strand (C1-C3) and included the four conserved ORFs found in all Subgroup I geminiviruses. A LIR and small intergenic region were also present. The conserved ORFs encoded proteins of predicted Musd\rm\sb{r}usd (kDa) of 10.9 (V1), 26.9-27.0 (CP), 31,5-31.6 (C1) and 17.7 (C2). Alignment of the genome sequences of the two clones with those of the previously reported sequences of severe symptom isolates, MSV-Ns and MSV-R, and a mild symptom isolate, MSV-Nm, did not show any LIR or V1 or V2 ORFs sequences that were unique to the three symptom phenotypes.

Biological sciences

geminiviruses

maize streak geminivirus

Plant pathology

Setaria verticillata

Zea mays

D. T. B. Gordon, David M.

P. Ngwira

Electronic name

p

[Thesis]

276903

a

Y