farag keyba | Umm Al-Qura University, Makkah, Saudi Arabia (original) (raw)

Papers by farag keyba

Journal of Stress Physiology & Biochemistry, 2014

Water stress is likely the most important factor that adversely affects plant growth and developm... more Water stress is likely the most important factor that adversely affects plant growth and development. In this study two wheat cultivars Gemmieza-7 (sensitive) and Sahel-1 (tolerant) were subjected to water stress and compared in terms of growth parameters (growth vigor of root and shoot), water relations (relative water content and saturation water deficit ) and protein as well as nucleic acids (DNA and RNA) content in flag leaves of both cultivars. In general, water stress caused noticeable reduction in almost all growth criteria of root, shoot and flag leaf which was consistent with the progressive alteration in water relations, protein and nucleic acids content of both cultivars during grain filling. Furthermore, degree of leaf succulence and degree of leaf sclerophylly were severely affected by water stress in both wheat cultivars. In relation to wheat cultivar, the sensitive was more affected by water stress than the tolerant one. Generally, the application of salicylic acid, t...

Journal of Plant Production, 2015

Production of new maize hybrids with desirable package of earliness and physiological maturity re... more Production of new maize hybrids with desirable package of earliness and physiological maturity related traits without compromising grains yield is critical for various agricultural systems worldwide. This investigation were carried out during 2012 season to evaluate the impact of the different genetic makeup of a set of thirteen new hybrids, developed by the authors during 2011 season, on flowering related traits such as anthesis, silking, anthesis-silking intervals (ASI), and the efficiency of light absorption of plant cover as well as physiological maturity related traits such as grains filling period, and grains filling rate. The impact of these traits on ear yield under both N stress and N sufficient conditions was also investigated. The results revealed that the tested hybrids exhibited significant differences in all tested flowering related traits. Based on the phenotype of their earliness traits (days from sowing to 50% flowering) and the general mean value of these traits (60.24 days for flowering), the tested hybrids were relatively categorized into early flowering early flowering (with number of days from ≤ 50 to 55 days, e.g. B73X PHG47,

Genetics, 2010

In Sorghum bicolor, a group of phytoalexins are induced at the site of infection by Colletotrichu... more In Sorghum bicolor, a group of phytoalexins are induced at the site of infection by Colletotrichum sublineolum, the anthracnose fungus. These compounds, classified as 3-deoxyanthocyanidins, have structural similarities to the precursors of phlobaphenes. Sorghum yellow seed1 (y1) encodes a MYB transcription factor that regulates phlobaphene biosynthesis. Using the candystripe1 transposon mutagenesis system in sorghum, we have isolated functional revertants as well as loss-of-function alleles of y1. These near-isogenic lines of sorghum show that, compared to functionally revertant alleles, loss of y1 lines do not accumulate phlobaphenes. Molecular characterization of two null y1 alleles shows a partial internal deletion in the y1 sequence. These null alleles, designated as y1-ww1 and y1-ww4, do not accumulate 3-deoxyanthocyanidins when challenged with the nonpathogenic fungus Cochliobolus heterostrophus. Further, as compared to the wild-type allele, both y1-ww1 and y1-ww4 show greater...

In sorghum, 3-deoxyflavonoid pigments or phlobaphenes observed in the pericarp of mature seed are... more In sorghum, 3-deoxyflavonoid pigments or phlobaphenes observed in the pericarp of mature seed are derived from flavan-4-ols through the flavonoid biosynthetic pathway. We show here that phlobaphenes accumulation in pericarp, glumes and leaves is genetically linked with the functional yellow seed1 (y1) gene. Molecular and genetic analysis was performed on a loss of function allele of y1 present in the line BTx623. This sorghum line does not accumulate any detectable levels of flavan-4-ols or visible phlobaphenes in pericarp, glumes and leaves. Molecular structure of the y1[BTx623] showed a deletion of 3218 bp which removes 5 0 non-coding, putative promoter, exon1, intron1, exon2, and part of the intron2 sequences. The null y1 allele designated as y1-ww (white pericarp, white glume) is not transcribed and this results in a loss of Y1-regulated expression of structural genes needed for the biosynthesis of flavan-4-ols. Further LC-MS analysis of seed extracts of a functional y1 allele detected the presence of positively charged compounds known as 3-deoxyanthocyanidins. Compounds identified were apigeninidin, luteolinidin, and a methoxylated derivative of apigeninidin. These compounds were not detected in BTx623 seed extracts. Previous studies have shown that 3-deoxyanthocyanidins are induced in sorghum leaves challenged with Colletotrichum sublineolum, a fungus that causes anthracnose in sorghum. Our results now provide an evidence for a common flavonoid pathway that may lead to the biosynthesis of flavan-4-ols and 3-deoxyanthocyanidins in sorghum.

Water stress is likely the most important factor that adversely affects plant growth and developm... more Water stress is likely the most important factor that adversely affects plant growth and development. In this study two wheat cultivars Gemmieza-7 (sensitive) and Sahel-1 (tolerant) were subjected to water stress and compared in terms of growth parameters (growth vigor of root and shoot), water relations (relative water content and saturation water deficit) and protein as well as nucleic acids (DNA and RNA) content in flag leaves of both cultivars. In general, water stress caused noticeable reduction in almost all growth criteria of root, shoot and flag leaf which was consistent with the progressive alteration in water relations, protein and nucleic acids content of both cultivars during grain filling. Furthermore, degree of leaf succulence and degree of leaf sclerophylly were severely affected by water stress in both wheat cultivars. In relation to wheat cultivar, the sensitive was more affected by water stress than the tolerant one. Generally, the application of salicylic acid, trehalose or their interaction induced marked increase in growth vigor of root and shoot, water relations and protein as well as nucleic acids in flag leaves of both wheat cultivars in compare with control and water stressed plants. In conclusion, Sahel-1 has suitable mechanisms to enable it to respond more effectively to water stress than Gemmieza-7.

Sorghum responds to the ingress of the fungal pathogen Colletotrichum sublineolum through the bio... more Sorghum responds to the ingress of the fungal pathogen Colletotrichum sublineolum through the biosynthesis of 3-deoxyanthocyanidin phytoalexins at the site of primary infection. Biosynthesis of 3-deoxyanthocyanidins in sorghum requires a MYB transcription factor encoded by yellow seed1 (y1), an orthologue of the maize gene pericarp color1 (p1). Maize lines with a functional p1 and flavonoid structural genes do not produce foliar 3-deoxyanthocyanidins in response to fungal ingress. To perform a comparative metabolic analysis of sorghum and maize 3-deoxyanthocyanidin biosynthetic pathways, we developed transgenic maize lines expressing the sorghum y1 gene. In maize, the y1 transgene phenocopied p1-regulated pigment accumulation in the pericarp and cob glumes. LC-MS profiling of fungus-challenged Y1-maize leaves showed induction of 3-deoxyanthocyanidins, specifically luteolinidin. Y1-maize plants also induced constitutive and higher levels of flavonoids in leaves. In response to Colletotrichum graminicola, Y1-maize showed a resistance response.

In sorghum, 3-deoxyflavonoid pigments or phlobaphenes observed in the pericarp of mature seed are... more In sorghum, 3-deoxyflavonoid pigments or phlobaphenes observed in the pericarp of mature seed are derived from flavan-4-ols through the flavonoid biosynthetic pathway. We show here that phlobaphenes accumulation in pericarp, glumes and leaves is genetically linked with the functional yellow seed1 (y1) gene. Molecular and genetic analysis was performed on a loss of function allele of y1 present in the line BTx623. This sorghum line does not accumulate any detectable levels of flavan-4-ols or visible phlobaphenes in pericarp, glumes and leaves. Molecular structure of the y1[BTx623] showed a deletion of 3218 bp which removes 5 0 non-coding, putative promoter, exon1, intron1, exon2, and part of the intron2 sequences. The null y1 allele designated as y1-ww (white pericarp, white glume) is not transcribed and this results in a loss of Y1-regulated expression of structural genes needed for the biosynthesis of flavan-4-ols. Further LC–MS analysis of seed extracts of a functional y1 allele detected the presence of positively charged compounds known as 3-deoxyanthocyanidins. Compounds identified were apigeninidin, luteolinidin, and a methoxylated derivative of apigeninidin. These compounds were not detected in BTx623 seed extracts. Previous studies have shown that 3-deoxyanthocyanidins are induced in sorghum leaves challenged with Colletotrichum sublineolum, a fungus that causes anthracnose in sorghum. Our results now provide an evidence for a common flavonoid pathway that may lead to the biosynthesis of flavan-4-ols and 3-deoxyanthocyanidins in sorghum.

Journal of Stress Physiology & Biochemistry, 2014

Journal of Plant Production, 2015

Genetics, 2010

Water stress is likely the most important factor that adversely affects plant growth and developm... more Water stress is likely the most important factor that adversely affects plant growth and development. In this study two wheat cultivars Gemmieza-7 (sensitive) and Sahel-1 (tolerant) were subjected to water stress and compared in terms of growth parameters (growth vigor of root and shoot), water relations (relative water content and saturation water deficit) and protein as well as nucleic acids (DNA and RNA) content in flag leaves of both cultivars. In general, water stress caused noticeable reduction in almost all growth criteria of root, shoot and flag leaf which was consistent with the progressive alteration in water relations, protein and nucleic acids content of both cultivars during grain filling. Furthermore, degree of leaf succulence and degree of leaf sclerophylly were severely affected by water stress in both wheat cultivars. In relation to wheat cultivar, the sensitive was more affected by water stress than the tolerant one. Generally, the application of salicylic acid, trehalose or their interaction induced marked increase in growth vigor of root and shoot, water relations and protein as well as nucleic acids in flag leaves of both wheat cultivars in compare with control and water stressed plants. In conclusion, Sahel-1 has suitable mechanisms to enable it to respond more effectively to water stress than Gemmieza-7.

In sorghum, 3-deoxyflavonoid pigments or phlobaphenes observed in the pericarp of mature seed are... more In sorghum, 3-deoxyflavonoid pigments or phlobaphenes observed in the pericarp of mature seed are derived from flavan-4-ols through the flavonoid biosynthetic pathway. We show here that phlobaphenes accumulation in pericarp, glumes and leaves is genetically linked with the functional yellow seed1 (y1) gene. Molecular and genetic analysis was performed on a loss of function allele of y1 present in the line BTx623. This sorghum line does not accumulate any detectable levels of flavan-4-ols or visible phlobaphenes in pericarp, glumes and leaves. Molecular structure of the y1[BTx623] showed a deletion of 3218 bp which removes 5 0 non-coding, putative promoter, exon1, intron1, exon2, and part of the intron2 sequences. The null y1 allele designated as y1-ww (white pericarp, white glume) is not transcribed and this results in a loss of Y1-regulated expression of structural genes needed for the biosynthesis of flavan-4-ols. Further LC–MS analysis of seed extracts of a functional y1 allele detected the presence of positively charged compounds known as 3-deoxyanthocyanidins. Compounds identified were apigeninidin, luteolinidin, and a methoxylated derivative of apigeninidin. These compounds were not detected in BTx623 seed extracts. Previous studies have shown that 3-deoxyanthocyanidins are induced in sorghum leaves challenged with Colletotrichum sublineolum, a fungus that causes anthracnose in sorghum. Our results now provide an evidence for a common flavonoid pathway that may lead to the biosynthesis of flavan-4-ols and 3-deoxyanthocyanidins in sorghum.