Genetic variation among three population for Old World Screwworm Chrysomya bezziana (Diptera: Caliphoridae) in Northern, Middle and Southern of Iraq by using RAPD-PCR technique

Soil bacteria Sinorhizobium meliloti had enormous agricultural value, due to their ability infixing nitrogen symbiotically with an important forage crop legume- alfalfa. The aim of thisstudy (i) isolate indigenous S. meliloti from different field sites in Iraq, (ii) evaluate the isolatestolerance to induce drought using polyethylene glycol-6000, (iii) assessing genetic diversity andgenetic relationships among isolates of natural population with drought tolerant abilities.Drought tolerance study revealed vast variations between Sinorhizobium isolates, the highesttolerant isolates to drought were twelve from total thirty 40%, tolerated from -3 up to -4 Mpa(mega pascal), while the drought sensitive isolates tolerated upto – 1.5 Mpa, except isolate Bs58which tolerated upto -1 Mpa water potential. The growth declined with the increase of droughtstress. Cluster analysis based on RAPD-PCR showed significant differences among S. melilotiisolates, and the results gave almost identical grouping of isolates in regards to droughtexperiment. Among indigenous isolates two divergent groups could be determined, the first majorgroup included drought tolerant isolates and the second major group comprised all droughtmoderate and sensitive isolates with 40% similarity between the two major groups.

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PCR-Based Genotyping of Epidemic and PreepidemicTrichoderma Isolates Associated with Green Mold ofAgaricus bisporus

Applied and Environmental Microbiology ◽

10.1128/aem.65.6.2674-2678.1999 ◽

1999 ◽

Vol 65 (6) ◽

pp. 2674-2678 ◽

Cited By ~ 21

Author(s):

X. Chen ◽

C. P. Romaine ◽

Q. Tan ◽

B. Schlagnhaufer ◽

M. D. Ospina-Giraldo ◽

...

Keyword(s):

Genetic Variation ◽

North America ◽

Agaricus Bisporus ◽

Rapd Markers ◽

Rapd Analysis ◽

Pcr Amplification ◽

Green Mold ◽

Rapd Pcr ◽

Cultivated Mushroom ◽

Highly Virulent

ABSTRACT We used randomly amplified polymorphic DNA (RAPD)-PCR to estimate genetic variation among isolates of Trichoderma associated with green mold on the cultivated mushroom Agaricus bisporus. Of 83 isolates examined, 66 were sampled during the recent green mold epidemic, while the remaining 17 isolates were collected just prior to the epidemic and date back to the 1950s.Trichoderma harzianum biotype 4 was identified by RAPD analysis as the cause of almost 90% of the epidemic-related episodes of green mold occurring in the major commercial mushroom-growing region in North America. Biotype 4 was more closely allied to T. harzianum biotype 2, the predominant pathogenic genotype in Europe, than to the less pathogenic biotype 1 and Trichoderma atroviride (formerly T. harzianum biotype 3). No variation in the RAPD patterns was observed among the isolates within biotype 2 or 4, suggesting that the two pathogenic biotypes were populations containing single clones. Considerable genetic variation, however, was noted among isolates of biotype 1 and T. atroviride from Europe. Biotype 4 was not represented by the preepidemic isolates of Trichoderma as determined by RAPD markers and PCR amplification of an arbitrary DNA sequence unique to the genomes of biotypes 2 and 4. Our findings suggest that the onset of the green mold epidemic in North America resulted from the recent introduction of a highly virulent genotype of the pathogen into cultivated mushrooms.

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