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Gu Y Filippi MD Cancelas JA Siefring JE Williams EP Jasti AC Harris CE Lee AW Prabhakar R Atkinson SJ Kwiatkowski DJ Williams DA 《Science (New York, N.Y.)》2003,302(5644):445-449
The Rho guanosine triphosphatases (GTPases) Rac1 and Rac2 are critical signaling regulators in mammalian cells. The deletion of both Rac1 and Rac2 murine alleles leads to a massive egress of hematopoietic stem/progenitor cells (HSC/Ps) into the blood from the marrow, whereas Rac1-/- but not Rac2-/- HSC/Ps fail to engraft in the bone marrow of irradiated recipient mice. In contrast, Rac2, but not Rac1, regulates superoxide production and directed migration in neutrophils, and in each cell type, the two GTPases play distinct roles in actin organization, cell survival, and proliferation. Thus, Rac1 and Rac2 regulate unique aspects of hematopoietic development and function. 相似文献
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Madhavan Srinivasan Satya Vijayalakshmi Kothandaraman Paranidharan Vaikuntavasan Velazhahan Rethinasamy 《Phytoparasitica》2014,42(4):437-444
Anthracnose, caused by Colletotrichum capsici, is a major disease of chilli (Capsicum annuum L.) affecting both fruit and seed quality. The pathogen is both internally and externally seedborne. However, a rapid and sensitive method for detection of this pathogen in seeds is currently limited. In this study, a polymerase chain reaction (PCR) method based on sequence characterized amplified region (SCAR) marker was developed for specific and sensitive detection of C. capsici in chilli seeds and fruits. The developed SCAR primers were highly specific to C. capsici and resulted in the amplification of an expected 250-bp fragment from genomic DNA of all seven of the C. capsici isolates tested. No amplification occurred when the SCAR primers were tested with genomic DNA from three other fungal isolates and four other Colletotrichum species. The SCAR primers successfully amplified similar sized fragments from DNA derived from C. capsici-infected chilli fruits. The molecular detection sensitivity of C. capsici was 1 pg of purified C. capsici DNA template and 25 ng of DNA from C. capsici-infected chilli fruits. A real-time PCR assay was also developed using SYBR Green chemistry for detection of C. capsici in chilli fruits and seeds. The standard curve obtained showed a linear correlation between copy number of the cloned target DNA sequence of C. capsici and cycle threshold (Ct) values, with R2 of 0.98. These PCR-based assays may be highly useful in detection of this important pathogen in chilli seeds and fruits in plant quarantine laboratories. 相似文献
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Vidhyasekaran P Ponmalar TR Samiyappan R Velazhahan R Vimala R Ramanathan A Paranidharan V Muthukrishnan S 《Phytopathology》1997,87(12):1258-1263
ABSTRACT Rhizoctonia solani, the rice sheath blight pathogen, produces a toxin that reproduces all symptoms of the disease. The toxin has been partially purified and it was found to be a carbohydrate containing glucose, mannose, N-acetylgalactosamine, and N-acetylglucosamine. The toxin was also detected in infected leaves. Highly virulent isolates produced more toxin than less virulent isolates. Several R. solani isolates from rice and one each from cotton and tomato produced a similar toxin. All rice cultivars tested were susceptible to the pathogen and sensitive to the toxin. Host specificity of the toxin has been demonstrated using hosts and nonhosts of the pathogen. 相似文献
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Journal of Plant Diseases and Protection - Foliar application of Bacillus subtilis strain AUBS1 significantly reduced the sheath blight disease of rice (Oryza sativa L.) under greenhouse... 相似文献
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Madhavan Srinivasan Paranidharan Vaikuntavasan Velazhahan Rethinasamy 《植物病害和植物保护杂志》2010,117(6):253-257
Journal of Plant Diseases and Protection - Chilli (Capsicum annuum) fruits showing symptoms of an-thracnose disease were collected from farmer’s fields in different chilli-growing areas of... 相似文献
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A. Ramesh Sundar R. Velazhahan R. Viswanathan P. Padmanaban P. Vidhyasekaran 《Phytoparasitica》2001,29(3):231-242
The effect of a novel synthetic signal molecule, acibenzolar-S-methyl (CGA-245704; benzo [1,2,3] thiadiazole-7-carbothioic
acid S-methyl ester), in inducing resistance in sugarcane against red rot disease caused by the fungusColletotrichum falcatum Went was studied. Application of CGA-245704 as a soil drench or along with marcotting rooting mixture induced resistance
in sugarcane to challenge inoculation withC. falcatum. When the pathogen was inoculated by the plug method, it caused discoloration in the untreated control stalk tissues; however,
in the stalk tissues pretreated with acibenzolar-S-methyl, pathogen colonization was considerably reduced. When the pathogen
was inoculated by nodal swabbing, its penetration was arrested in the sensitized stalk tissues. An induced systemic resistance
effect was found to persist up to 30 days in the pretreated cut canes. Increased phenolic content and accumulation of pathogenesis-related
(PR) proteins,viz., chitinase, β-1,3-glucanase and thaumatin-like protein (PR-5), were observed in sugarcane plants treated with acibenzolar-S-methyl. 相似文献
7.
Purification of an Elicitor-Inducible Antifungal Chitinase from Suspension-Cultured Rice Cells 总被引：1，自引：0，他引：1
Suspension-cultured rice cells showed an appreciable amount of chitinase activity when the cultured cells were treated with
an elicitor isolated fromRhizoctonia solani, the rice sheath blight pathogen. A fivefold increase in chitinase activity was observed 24 h after elicitor treatment. The
elicitor-inducible chitinase was purified by ammonium sulfate fractionation, chitin affinity chromatography and gel filtration.
Its molecular weight is 35 kDa and it has an isoelectric point of 8.3. The 35 kDa basic chitinase inhibited mycelial growth
ofR. solani in vitro. Morphological changes appeared within 1 h following exposure of mycelium to the chitinase. The hyphal tip showed marked
swelling and subsequently lysis was also observed. 相似文献
8.
P. Vidhyasekaran N. Kamala A. Ramanathan K. Rajappan V. Paranidharan R. Velazhahan 《Phytoparasitica》2001,29(2):155-166
When lower leaves of rice plants were inoculated with powder formulation of a saprophytic strain ofPseudomonas fluorescens, Pfl, upper leaves, in addition to the inoculated lower leaves, showed resistance to the rice bacterial blight pathogenXanthomonas oryzae pv.oryzae. When the leaves were challenge-inoculated withX. oryzae pv.oryzae 4 days afterP. fluorescens application on lower leaves, the disease intensity in upper leaves decreased from 6.7 to 1.1. When rice seeds were treated
with the formulation ofP. fluorescens Pfl and sown, 30-day-old seedlings showed resistance toX. oryzae pv.oryzae and the disease intensity decreased from 6.8 to 1.2. The induced resistance was transient; leaves sprayed withP. fluorescens Pfl at 30 days after treatment and leaves of 60-day-old seedlings fromP. fluorescens-treated seeds did not show resistance to the pathogen. In field trials, seed treatment followed by foliar application of the powder
formulation ofP. fluorescens Pfl effectively controlled rice bacterial blight and increased the yield. In the induced resistant leaves a sharp increase
in lignification and activities of peroxidase, phenylalanine ammonia-lyase and 4-coumarate: CoA ligase was observed when the
leaves were challenge-inoculated withX. oryzae pv.oryzae. An approximately threefold increase in lignin content, peroxidase activity and phenylalanine ammonia-lyase activity and a
fivefold increase in 4-coumarate: CoA ligase activity were observed 5 days after challenge inoculation withX. oryzae pv.oryzae in rice leaves pretreated withP. fluorescens for 5 days. A similar increase in defense-related activities was not observed in susceptible interactions or inP. fluorescens-treated plants at later stages of interactions when no resistance to the pathogen was observed. 相似文献
9.
The host background of rice influences the resistance expression of a three genes pyramid (xa5 + xa13 + Xa21) to bacterial blight (Xanthomonas oryzae pv. oryzae) pathotypes of Indian mainland and Bay islands 
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下载免费PDF全文 Krishnan Sakthivel Raj K. Gautam Kaari Manigundan Reena Singh Jegadeesan Ramalingam Gouri S. Laha Aundy Kumar Rethinasamy Velazhahan 《Plant Breeding》2017,136(3):357-364
Bacterial blight (BB) is a major disease of rice for which host resistance is the only effective solution. The three genes pyramid xa5 + xa13 + Xa21 is recently the most utilized combination for developing resistant varieties through marker‐assisted breeding. Our study was carried out to elicit the detailed response of twenty lines possessing these three genes in five genetic backgrounds to twelve diverse BB pathotypes in India. The lines developed from ADT 47 variety showed incomplete resistance to most of the pathotypes, whereas susceptibility varied from 8.3% to 16.6% in ADT 43 and IR24, respectively. However, in IMP ASD16/60 and Improved Samba Mahsuri, complete resistance against all pathotypes was observed. The overall results confirmed that genetic background plays crucial role for the effective expression of xa5 + xa13 + Xa21 combination. Molecular studies did not reveal correlation between origin of pathotypes and their virulence potential. It is suggested to deploy Improved Samba Mahsuri, IMP ASD 16/60 and AD1306 varieties in the bacterial blight prone areas or use them as donors for realizing wider and durable resistance. 相似文献
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