Accumulation of Transcripts Abundance after Barley Inoculation with Cochliobolus sativus

Arabi, Mohammad Imad Eddin,AL-Daoude, Antonious,Shoaib, Amina,Jawhar, Mohammad The Korean Society of Plant Pathology 2015 Plant Pathology Journal Vol.31 No.1

Spot blotch caused by the hemibiotrophic pathogen Cochliobolus sativus has been the major yield-reducing factor for barley production during the last decade. Monitoring transcriptional reorganization triggered in response to this fungus is an essential first step for the functional analysis of genes involved in the process. To characterize the defense responses initiated by barley resistant and susceptible cultivars, a survey of transcript abundance at early time points of C. sativus inoculation was conducted. A notable number of transcripts exhibiting significant differential accumulations in the resistant and susceptible cultivars were detected compared to the non-inoculated controls. At the p-value of 0.0001, transcripts were divided into three general categories; defense, regulatory and unknown function, and the resistant cultivar had the greatest number of common transcripts at different time points. Quantities of differentially accumulated gene transcripts in both cultivars were identified at 24 h post infection, the approximate time when the pathogen changes trophic lifestyles. The unique and common accumulated transcripts might be of considerable interest for enhancing effective resistance to C. sativus.

Accumulation of Transcripts Abundance after Barley Inoculation with Cochliobolus sativus

Mohammad Imad Eddin Arabi,Antonious Al-Daoude,Amina Shoaib,Mohammad Jawhar 한국식물병리학회 2015 Plant Pathology Journal Vol.31 No.1

Spot blotch caused by the hemibiotrophic pathogenCochliobolus sativus has been the major yield-reducingfactor for barley production during the last decade. Monitoring transcriptional reorganization triggeredin response to this fungus is an essential first step forthe functional analysis of genes involved in the process. To characterize the defense responses initiated bybarley resistant and susceptible cultivars, a survey oftranscript abundance at early time points of C. sativusinoculation was conducted. A notable number of transcriptsexhibiting significant differential accumulationsin the resistant and susceptible cultivars were detectedcompared to the non-inoculated controls. At the p-valueof 0.0001, transcripts were divided into three generalcategories; defense, regulatory and unknown function,and the resistant cultivar had the greatest number ofcommon transcripts at different time points. Quantitiesof differentially accumulated gene transcripts inboth cultivars were identified at 24 h post infection, theapproximate time when the pathogen changes trophiclifestyles. The unique and common accumulated transcriptsmight be of considerable interest for enhancingeffective resistance to C. sativus.

Greenhouse Method for Assessing Spot Blotch Resistance in Barley

Mohammad Imad Eddin Arabi,Mohammad Jawhar 한국식물병리학회 2010 Plant Pathology Journal Vol.26 No.4

New sources of barley (Hordeum vulgare L.) resistant to spot blotch, caused by Cochliobolus sativus, are needed to provide effective resistance because of the rapid change pathotype patterns of C. sativus in fields. The purposes of our study were to develop a method to screen barley for resistance to spot blotch disease and then use this methodology to screen barley genotypes for resistance to the major virulent pathotype Pt4 in barley populations in Syria. A transparent tape method,in which a conidial suspension of C. sativus was dropped onto transparent tape and placed, treated-side down, on the second leaf surface of barley plants. Disease symptoms of fungus were easily detected on the leaves covered by the transparent tape after 48h of inoculation. The transparent tape method was repeatable and the disease scores obtained were correlated (r = 0.91, P = 0.001) with those obtained by the seedling assay. This method may be beneficial in various plant pathology breeding programs.

Greenhouse Method for Assessing Spot Blotch Resistance in Barley

Arabi, Mohammad Imad Eddin,Jawhar, Mohammad The Korean Society of Plant Pathology 2010 Plant Pathology Journal Vol.26 No.4

New sources of barley (Hordeum vulgare L.) resistant to spot blotch, caused by Cochliobolus sativus, are needed to provide effective resistance because of the rapid change pathotype patterns of C. sativus in fields. The purposes of our study were to develop a method to screen barley for resistance to spot blotch disease and then use this methodology to screen barley genotypes for resistance to the major virulent pathotype Pt4 in barley populations in Syria. A transparent tape method, in which a conidial suspension of C. sativus was dropped onto transparent tape and placed, treated-side down, on the second leaf surface of barley plants. Disease symptoms of fungus were easily detected on the leaves covered by the transparent tape after 48h of inoculation. The transparent tape method was repeatable and the disease scores obtained were correlated (r = 0.91, P = 0.001) with those obtained by the seedling assay. This method may be beneficial in various plant pathology breeding programs.

A Simple Method for Assessing Severity of Common Root Rot on Barley

Mohammad Imad Eddin Arabi,Mohammad Jawhar 한국식물병리학회 2013 Plant Pathology Journal Vol.29 No.4

Common root rot caused by Cochliobolus sativus is a serious disease of barley. A simple and reliable method for assessing this disease would enhance our capacity in identifying resistance sources and developing resistant barley cultivars. In searching for such a method, a conidial suspension of C. sativus was dropped onto sterilized elongated subcrown internodes and incubated in sandwich filter paper using polyethylene transparent envelopes. Initial disease symptoms were easily detected after 48h of inoculation. Highly significant correlation coefficients were found in each experiment (A, B and C)between sandwich filter paper and seedling assays,indicating that this testing procedure was reliable. The method presented facilitates a rapid pre-selection under uniform conditions which is of importance from a breeder's point of view.

A Simple Method for Assessing Severity of Common Root Rot on Barley

Arabi, Mohammad Imad Eddin,Jawhar, Mohammad The Korean Society of Plant Pathology 2013 Plant Pathology Journal Vol.29 No.4

Common root rot caused by Cochliobolus sativus is a serious disease of barley. A simple and reliable method for assessing this disease would enhance our capacity in identifying resistance sources and developing resistant barley cultivars. In searching for such a method, a conidial suspension of C. sativus was dropped onto sterilized elongated subcrown internodes and incubated in sandwich filter paper using polyethylene transparent envelopes. Initial disease symptoms were easily detected after 48h of inoculation. Highly significant correlation coefficients were found in each experiment (A, B and C) between sandwich filter paper and seedling assays, indicating that this testing procedure was reliable. The method presented facilitates a rapid pre-selection under uniform conditions which is of importance from a breeder's point of view.

Physiological and Morphological Aspects of Bipolaris sorokiniana Conidia Surviving on Wheat Straw

Duveiller, E.,Chand, R.,Singh, H.V.,Joshi, A.K. The Korean Society of Plant Pathology 2002 Plant Pathology Journal Vol.18 No.6

Wheat samples showing typical spot blotch symptoms on stems and sheaths were collected from the field after physiological maturity, and were sealed in paper bags and stored in the laboratory at room temperature to study the survival of Bipolaris sorokiniana conidia on wheat straw. The materials were observed at monthly intervals to assess the conidia viability during storage. After 4 months, the frequency of individual conidia already present on wheat straw at the time of sampling was reduced and appeared to be progressively replaced by the formation of round structures consist-ing of conidia aggregates. After 5 months, distinct, individual conidia were no longer detected, and only 'clumps of conidia' were observed. These dark black aggregates or 'clumps of conidia’measured 157-170$\mu\textrm{m}$ in diameter and were grouped into boat-shaped olivacious conidia showing thick wall and measuring 50-82$\times$20-30$\mu\textrm{m}$. The germination was unipolar and below 0.5%, suggesting the occurrence of dormancy, In contrast, individual conidium produced on wheat during the growing season were 96-130$\times$16-20$\mu\textrm{m}$, slightly curved, hyaline to light pale, and euseptate with a bipolar germination reaching 98-100%. Bipolaris sorokiniana conidia produced on PDA were 55-82$\times$20-27$\mu\textrm{m}$, tapered at both ends, dark brown to olivacious, distoseptate, showed up to 1% germination, and were predominantly unipolar. Results of the present study suggest that B. sorokiniana conidia belonged to two different physiological categories corresponding to the pathogen's infection phase and its survival, respectively. The infection phase is characterized by a high germination percentage as opposed to the survival phase harboring apparent dormancy.

Physiological and Morphological Aspects of Bipolaris sorokiniana Conidia Surviving on Wheat Straw

R.Chand,H.V.Singh,A.K.Joshi,E.Duveiller 한국식물병리학회 2002 Plant Pathology Journal Vol.18 No.6

Wheat samples showing typical spot blotch symptoms on stems and sheaths were collected from the field after physiological maturity, and were sealed in paper bags and stored in the laboratory at room temperature to study the survival of Bipolaris sorokiniana conidia on wheat straw. The materials were observed at monthly intervals to assess the conidia viability during storage. After 4 months, the frequency of individual conidia already present on wheat straw at the time of sampling was reduced and appeared to be progressively replaced by the formation of round structures consisting of conidia aggregates. After 5 months, distinct, individual conidia were no longer detected, and only ‘clumps of conidia’ were observed. These dark black aggregates or ‘clumps of conidia’ measured 157-170 mm in diameter and were grouped into boat-shaped olivacious conidia showing thick wall and measuring 50-82 ´ 20-30 mm. The germination was unipolar and below 0.5%, suggesting the occurrence of dormancy. In contrast, individual conidium produced on wheat during the growing season were 96-130 ´ 16-20 mm, slightly curved, hyaline to light pale, and euseptate with a bipolar germination reaching 98-100%. Bipolaris sorokiniana conidia produced on PDA were 55-82 ´ 20- 27 mm, tapered at both ends, dark brown to olivacious, distoseptate, showed up to 1% germination, and were predominantly unipolar. Results of the present study suggest that B. sorokiniana conidia belonged to two different physiological categories corresponding to the pathogen's infection phase and its survival, respectively. The infection phase is characterized by a high germination percentage as opposed to the survival phase harboring apparent dormancy.