Effect of enhanced UV-B radiation and inoculated blast isolate (Magnaporthe grisea) on phenylalanine ammonial-yase activity and flavonoid content in seedlings of two rice cultivars

2010 ◽  
Vol 18 (4) ◽  
pp. 856-860 ◽  
Author(s):  
Yuan LI ◽  
Xiao-Xiao GAO ◽  
Zhao-Hua GAO ◽  
Yong-Mei HE ◽  
Jian-Jun CHEN ◽  
...  
Keyword(s):  
Magnaporthe Grisea ◽  
Rice Cultivars ◽  
Flavonoid Content

scholarly journals Identification of an Avirulence Gene in the Fungus Magnaporthe grisea Corresponding to a Resistance Gene at the Pik Locus

2005 ◽  
Vol 95 (7) ◽  
pp. 768-772 ◽  
Author(s):  
N. Yasuda ◽  
M. T. Noguchi ◽  
Y. Fujita
Keyword(s):  
Resistance Gene ◽  
Genetic Basis ◽  
Magnaporthe Grisea ◽  
Fragment Length Polymorphism ◽  
Random Amplified Polymorphic Dna ◽  
Genetic Maps ◽  
Avirulence Gene ◽  
Chinese Isolate ◽  
Rice Cultivars ◽  
Almost All

A rice isolate of Magnaporthe grisea collected from China was avirulent on rice cvs. Hattan 3 and 13 other Japanese rice cultivars. The rice cv. Hattan 3 is susceptible to almost all Japanese blast fungus isolates from rice. The genetic basis of avirulence in the Chinese isolate on Japanese rice cultivars was studied using a cross between the Chinese isolate and a laboratory isolate. The segregation of avirulence or virulence was studied in 185 progeny from the cross, and monogenic control was demonstrated for avirulence to the 14 rice cultivars. The resistance gene that corresponds to the avirulence gene (Avr-Hattan 3) is thought to be located at the Pik locus. Resistance and susceptibility in response to the Chinese isolate in F3 lines of a cross of resistant and susceptible rice cultivars were very similar to the Pik tester isolate, Ken54-20. Random amplified polymorphic DNA markers and restriction fragment length polymorphism markers from genetic maps of the fungus were used to construct a partial genetic map of Avr-Hattan 3. We obtained several flanking markers and one co-segregated marker of Avr-Hattan 3 in the 144 mapping population.

scholarly journals Estimation of phenotypic diversity in field populations of Magnaporthe grisea from two upland rice cultivars

2007 ◽  
Vol 32 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Gisele B. Silva ◽  
Laércio Zambolim ◽  
Anne S. Prabhu ◽  
Leila G. Araújo ◽  
Francisco J.P. Zimmermann
Keyword(s):  
Standard Deviation ◽  
Magnaporthe Grisea ◽  
Upland Rice ◽  
Phenotypic Diversity ◽  
Diversity Index ◽  
Rice Cultivars ◽  
Simpson Index ◽  
Reaction Type ◽  
Growing Seasons ◽  
Differential Cultivars

The phenotypic diversity of Magnaporthe grisea was evaluated based on leaf samples with blast lesions collected from eight commercial fields of the upland rice cultivars 'BRS Primavera' and 'BRS Bonança', during the growing seasons of 2001/2002 and 2002/2003, in Goias State. The number of M. grisea isolates from each field utilized for virulence testing varied from 28 to 47. Three different indices were used based on reaction type in the eight standard international differentials and eight Brazilian differentials. The M. grisea subpopulations of ´Primavera' and 'Bonança', as measured by Simpson, Shannon and Gleason indices, showed similar phenotypic diversities. The Simpson index was more sensitive relation than those of Shannon and Gleason for pathotype number and standard deviation utilizing Brazilian differentials. However, the Gleason index was sensitive to standard deviation for international differentials. The sample size did not significantly influence the diversity index. The two sets of differential cultivars used in this study distinguished phenotypic diversity in different ways in all of the eight subpopulations analyzed. The phenotypic diversity determined based on eight differential Brazilian cultivars was lower in commercial rice fields of 'Primavera' than in the fields of 'Bonança,' independent of the diversity index utilized, year and location. Considering the Brazilian differentials, the four subpopulations of 'BRS Primavera' did not show evenness in distribution and only one pathotype dominated in the populations. The even distribution of pathotype was observed in three subpopulations of 'BRS Bonança'. The pathotype diversity of M. grisea was determined with more precision using Brazilian differentials and Simpson index.

scholarly journals Magnaporthe grisea genes for pathogenicity and virulence identified through a series of backcrosses.

Genetics ◽  
1991 ◽  
Vol 127 (1) ◽  
pp. 87-101 ◽  
Author(s):  
B Valent ◽  
L Farrall ◽  
F G Chumley
Keyword(s):  
Dna Sequences ◽  
Magnaporthe Grisea ◽  
Pathogenic Fungus ◽  
Field Isolate ◽  
Recurrent Parent ◽  
High Fertility ◽  
Rice Cultivars ◽  
Avirulence Genes ◽  
Chromosomal Dna ◽  
Fertile Female

Abstract We have identified genes for pathogenicity toward rice (Oryza sativa) and genes for virulence toward specific rice cultivars in the plant pathogenic fungus Magnaporthe grisea. A genetic cross was conducted between the weeping lovegrass (Eragrostis curvula) pathogen 4091-5-8, a highly fertile, hermaphroditic laboratory strain, and the rice pathogen O-135, a poorly fertile, female-sterile field isolate that infects weeping lovegrass as well as rice. A six-generation backcrossing scheme was then undertaken with the rice pathogen as the recurrent parent. One goal of these crosses was to generate rice pathogenic progeny with the high fertility characteristic of strain 4091-5-8, which would permit rigorous genetic analysis of rice pathogens. Therefore, progeny strains to be used as parents for backcross generations were chosen only on the basis of fertility. The ratios of pathogenic to nonpathogenic (and virulent to avirulent) progeny through the backcross generations suggested that the starting parent strains differ in two types of genes that control the ability to infect rice. First, they differ by polygenic factors that determine the extent of lesion development achieved by those progeny that infect rice. These genes do not appear to play a role in infection of weeping lovegrass because both parents and all progeny infect weeping lovegrass. Second, the parents differ by simple Mendelian determinants, "avirulence genes," that govern virulence toward specific rice cultivars in all-or-none fashion. Several crosses confirm the segregation of three unlinked avirulence genes, Avr 1-CO39, Avr 1-M201 and Avr1-YAMO, alleles of which determine avirulence on rice cultivars CO39, M201, and Yashiro-mochi, respectively. Interestingly, avirulence alleles of Avr1-CO39, Avr1-M201 and Avr1-YAMO were inherited from the parent strain 4091-5-8, which is a nonpathogen of rice. Middle repetitive DNA sequences ("MGR sequences"), present in approximately 40-50 copies in the genome of the rice pathogen parent, and in very low copy number in the genome of the nonpathogen of rice, were used as physical markers to monitor restoration of the rice pathogen genetic background during introgression of fertility. The introgression of highest levels of fertility into the most successful rice pathogen progeny was incomplete by the sixth generation, perhaps a consequence of genetic linkage between genes for fertility and genes for rice pathogenicity. One chromosomal DNA segment with MGR sequence homology appeared to be linked to the gene Avr1-CO39. Finally, many of the crosses described in this paper exhibited a characteristic common to many crosses involving M. grisea rice pathogen field isolates.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Expression of Magnaporthe grisea Avirulence Gene ACE1 Is Connected to the Initiation of Appressorium-Mediated Penetration

2007 ◽  
Vol 6 (3) ◽  
pp. 546-554 ◽  
Author(s):  
Isabelle Fudal ◽  
Jérôme Collemare ◽  
Heidi U. Böhnert ◽  
Delphine Melayah ◽  
Marc-Henri Lebrun
Keyword(s):  
Host Plant ◽  
Magnaporthe Grisea ◽  
Plant Cell Wall ◽  
Current Control ◽  
Camp Signaling ◽  
Avirulence Gene ◽  
Rice Cultivars ◽  
Avirulence Genes ◽  
Specific Expression ◽  
Melanin Biosynthesis

ABSTRACT Magnaporthe grisea is responsible for a devastating fungal disease of rice called blast. Current control of this disease relies on resistant rice cultivars that recognize M. grisea signals corresponding to specific secreted proteins encoded by avirulence genes. The M. grisea ACE1 avirulence gene differs from others, since it controls the biosynthesis of a secondary metabolite likely recognized by rice cultivars carrying the Pi33 resistance gene. Using a transcriptional fusion between ACE1 promoter and eGFP, we showed that ACE1 is only expressed in appressoria during fungal penetration into rice and barley leaves, onion skin, and cellophane membranes. ACE1 is almost not expressed in appressoria differentiated on Teflon and Mylar artificial membranes. ACE1 expression is not induced by cellophane and plant cell wall components, demonstrating that it does not require typical host plant compounds. Cyclic AMP (cAMP) signaling mutants ΔcpkA and Δmac1 sum1-99 and tetraspanin mutant Δpls1::hph differentiate melanized appressoria with normal turgor but are unable to penetrate host plant leaves. ACE1 is normally expressed in these mutants, suggesting that it does not require cAMP signaling or a successful penetration event. ACE1 is not expressed in appressoria of the buf1::hph mutant defective for melanin biosynthesis and appressorial turgor. The addition of hyperosmotic solutes to buf1::hph appressoria restores appressorial development and ACE1 expression. Treatments of young wild-type appressoria with actin and tubulin inhibitors reduce both fungal penetration and ACE1 expression. These experiments suggest that ACE1 appressorium-specific expression does not depend on host plant signals but is connected to the onset of appressorium-mediated penetration.

scholarly journals The Genomic Dynamics and Evolutionary Mechanism of the Pi2/9 Locus in Rice

2007 ◽  
Vol 20 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Bo Zhou ◽  
Maureen Dolan ◽  
Hajime Sakai ◽  
Guo-Liang Wang
Keyword(s):  
Magnaporthe Grisea ◽  
Sequence Divergence ◽  
Valuable Insight ◽  
Gene Complex ◽  
Rice Cultivars ◽  
Orthologous Relationship ◽  
Regulatory Regions ◽  
Evolutionary Mechanism ◽  
Genetic Events ◽  
Insight Into

The Pi2/9 locus contains at least four resistance specificities to Magnaporthe grisea and belongs to a gene complex comprised of multiple genes that encode highly homologous nucleotide binding site (NBS) and leucine rich repeat (LRR) proteins. To investigate the genetic events involved in the evolution of the Pi2/9 locus, we analyzed the Pi2/9 locus at the inter- and intralocus levels in five rice cultivars. The NBS-LRR genes in the five cultivars belong to the same phylogenetic clade among rice NBS-LRR genes, and all have a phase-2 intron at the N-terminus. However, the paralogs within each haplotype show a significant sequence divergence and their N-terminal intron and 5′ regulatory regions are very different. On the contrary, the orthologs from different haplotypes are highly similar, indicating an obvious orthologous relationship has been maintained during the evolution of the Pi2/9 locus. These results suggest that sequence diversification in the 5′ regulatory regions and N-terminal introns of the paralogs may have led to suppression of meiotic recombination between the paralogs within each haplotype, facilitating the maintenance of the orthologous relationship among rice cultivars. Our observations provide valuable insight into the genomic dynamics and evolutionary mechanism of an NBS-LRR resistance-gene complex in rice.

scholarly journals Gain of Virulence Caused by Insertion of a Pot3 Transposon in a Magnaporthe grisea Avirulence Gene

2001 ◽  
Vol 14 (5) ◽  
pp. 671-674 ◽  
Author(s):  
Seogchan Kang ◽  
Marc Henri Lebrun ◽  
Leonard Farrall ◽  
Barbara Valent
Keyword(s):  
Disease Resistance ◽  
Resistance Gene ◽  
Magnaporthe Grisea ◽  
Rice Cultivar ◽  
Avirulence Gene ◽  
Disease Resistance Gene ◽  
Rice Cultivars

The avirulence gene AVR-Pita in Magnaporthe grisea prevents the fungus from infecting rice cultivars carrying the disease resistance gene Pi-ta. Insertion of Pot3 transposon into the promoter of AVR-Pita caused the gain of virulence toward Yashiro-mochi, a rice cultivar containing Pi-ta, which demonstrated the ability of Pot3 to move within the M. grisea genome. The appearance of Pot3 in M. grisea seems to predate the diversification of various host-specific forms of the fungus.

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