USE OF RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) TO IDENTIFY SHORT-DAY GRANO-TYPE ONION CULTIVARS

Nineteen random primers yielded 36 PCR-amplified products of Allium cepa profiles of each of 15 short-day grano-type onionsgrown commercially in Texas and Southern United States were compared. Several PCR productswere unique among the cultivars and can be used to differentiate among the onion cultivars investigated. A phenogram of the cultivars based on the co-occurrences of the PCR products was derived.

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A Rapid Survey of Avirulence Genes in Field Isolates of Magnaporthe oryzae

Plant Disease ◽

10.1094/pdis-08-19-1688-re ◽

2020 ◽

Vol 104 (3) ◽

pp. 717-723

Author(s):

Zhen Zhang ◽

Yulin Jia ◽

Yanli Wang ◽

Guochang Sun

Keyword(s):

United States ◽

Magnaporthe Oryzae ◽

Blast Resistance ◽

Blast Disease ◽

Southern United States ◽

R Genes ◽

Field Isolates ◽

Pcr Products ◽

Avr Gene ◽

Avr Genes

Magnaporthe oryzae is the causal agent for the devastating disease rice blast. The avirulence (AVR) genes in M. oryzae are required to initiate robust disease resistance mediated by the corresponding resistance (R) genes in rice. Therefore, monitoring pathogen AVR genes is important to predict the stability of R gene-mediated blast resistance. In the present study, we analyzed the DNA sequence dynamics of five AVR genes, namely, AVR-Pita1, AVR-Pik, AVR-Pizt, AVR-Pia, and AVR-Pii, in field isolates of M. oryzae in order to understand the effectiveness of the R genes, Pi-ta, Pi-k, Pi-zt, Pia, and Pii in the Southern U.S. rice growing region. Genomic DNA of 258 blast isolates collected from commercial fields of the Southern UNITED STATES during 1975–2009 were subjected to PCR amplification with AVR gene-specific PCR markers. PCR products were obtained from 232 isolates. The absence of PCR products in the remaining 26 isolates suggests that these isolates do not contain the tested AVR genes. Amplified PCR products were subsequently gel purified and sequenced. Based on the presence or absence of the five AVR genes, 232 field isolates were classified into 10 haplotype groups. The results revealed that 174 isolates of M. oryzae carried AVR-Pita1, 225 isolates carried AVR-Pizt, 44 isolates carried AVR-Pik, 3 isolates carried AVR-Pia, and one isolate carried AVR-Pii. AVR-Pita1 was highly variable, and 40 AVR-Pita1 haplotypes were identified in avirulent isolates. AVR-Pik had four nucleotide sequence site changes resulting in amino acid substitutions, whereas three other AVR genes, AVR-Pizt, AVR-Pia, and AVR-Pii, were relatively stable. Two AVR genes, AVR-Pik and AVR-Pizt, were found to exist in relatively larger proportions of the tested field isolates, which suggested that their corresponding R genes Pi-k and Pi-zt can be deployed in preventing blast disease in the Southern UNITED STATES in addition to Pi-ta. This study demonstrates that continued AVR gene monitoring in the pathogen population is critical for ensuring the effectiveness of deployed blast R genes in commercial rice fields.

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RANDOM AMPLIFIED POLYMORPHIC DNA (RAPDs) DETECTS PATTERNS OF GENETIC DIVERSITY IN DIPLOID MUSA ACUMINATA COLLA

HortScience ◽

10.21273/hortsci.27.6.660b ◽

1992 ◽

Vol 27 (6) ◽

pp. 660b-660

Author(s):

Robert L. Jarret

Keyword(s):

Random Amplified Polymorphic Dna ◽

Geographic Origin ◽

Morphological Characteristics ◽

Principal Component ◽

Chain Reaction ◽

Banding Patterns ◽

Random Primers ◽

Pcr Products ◽

Polymerase Chain

Patterns of diversity among thirty diploid clones of banana (Musa acuminata Colla.), collected in Papua New Guinea and the surrounding islands between 1987 and 1989, were examined genetically using the polymerase chain reaction (PCR) and random primers, to detect random amplified polymorphic DNA (RAPDs). PCR products were visualized on ethidium bromide stained agarose gels. Twenty of 60 random primers examined detected RAPDS in CTAB-extracted genomic DNA. Banding patterns ranged from very simple (1 or 2 bands/gel) to very complex (more than 20 bands/gel). All 30 Musa clones were distinguishable from each other based on their unique RAPD banding pattern. Principal component analysis (PCA) revealed several clusters of closely related clones within the materials examined. However, these clusterings were not correlated with either the geographic origin or the morphological characteristics of the clones. A role of the use of RAPDs in germplasm characterization is discussed.

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