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Abstract The present investigation was conducted to study the following: First, the phylogenetic relation-ships between ten Egyptian Hordeum vulgare L varieties depending on agro-morphological criteria, molecular genetic markers (RAPD-PCR, ISSR-PCR and microsatellite SSR-PCR) and protein banding patterns electrophoresis, also determination of the viable marker which has potential power in discrimination and identification of cultivars and landraces, also identification of landraces in the present study. Second, study the effect of salt stress by NaCl treatments on analysis of variance of agro-morphological traits to identify which varieties are more tolerant to salinity. Also, study the effect of salinity on soluble protein contents and proline concentrations in leaves of the studied varieties. Third, study the effect of salinity in expression of betaine aldehyde dehydrogenase gene. Also this gene was isolated and it was alignmented in GenBank to identify it. The seeds of seven cultivars of Hordeum vulgaries L. were used, Giza 123, Giza 126, Giza 127, Giza 128, Giza 129, Giza 130 and Giza 2000 were obtained from Agricultural Research Center, Giza, Egypt and three landraces were obtained from Egyptian National GenBank, Agricultural Research Center, Giza, Egypt, under code number (11557, 11580 and 113737), these landraces are collected from Sinai, El-Aresh (El-Kheroba, El-Sheikh Zuwaid) and Ras Sedr (Wadi Sedr). Summary 161 The obtained results could be summarized as follows: I-Agro-morphological Criteria studies: 1- Ten studied Hordeum vulgare L variedies were discriminated and identified to determine the phylogenetic relationships between them depending on analysis of variance of studied Agro-morphological traits (branch number/plant, shoot length (cm), root length (cm), node number/plant, spike length (cm), spike weight (gm), no. of grains/spike, grain weight /spike (gm) and grain weight/plant (gm)) The result of agro-morphological phenogram by UPGMA indicated that the agro-morphological phenogram is completely similar to the pedigree of studied varieties. 2- from the results obtained from studing the effect of different concentrations of NaCl (control, 9000, 12000 and 15000 ppm) on studied agro-morphological traits of ten studied barley varieties, we concluded that Giza 2000 cultivar and Wadi Sedr landrace are considered more tolerance varieties between studied varieties while Giza 129 cultivar considered a sensitive cultivar. II- Molecular genetic marker studies Classification technique based on the use of molecular markers like RAPD, ISSR and SSR provide a much more accurate and powerful means of analyzing genetic relationship The result of RAPD, ISSR and SSR fingerprinting patterns revealed different levels of polymorphism among the ten varieties. This corresponds to a level of polymorphism of 41.77%, 62.02% and 61.22% respectively this reflect that ISSR markers are more Summary 162 discriminating than SSR and RAPD to evaluate the genetic diversity and relationship among studied varieties. The phenogram obtained from the collective data of three markers classified the three landraces in separate cluster with Giza 2000 this indicated that there are a similarity distance between studied landraces and Giza 2000. III- gene expression studies under salinity and BADH gene isolation 1- We studied the protein electrophoresis banding patterns on ten studied varieties to determine the phylogenetic relationships between them by phenogram of UPGMA, from result, we found that the studied landraces grouped into a separate cluster and had a high similarity between them, then the three studied landraces had high similarity with Giza 2000, also Giza 128, Giza 129 and Giza 130 have the same similarity degree. 2- from studying the effect of salinity on protein electrophoresis banding pattern of ten studied varieties at three sampling time points (sampling after 24 hours, 1st week and 2nd week salt treatment). from results we found that a maximum polymorphism was observed at third time point (sampling after 2nd week salt treatments), but showed the lowest variation. While sampling after 24 hours and 1st week salt treatment showed a maximum variation. Also the bands intensity shown maximum intensity at first time point (sampling after 24 hours), while showed minimum intensity at third time point (sampling after 2nd week salt treatments). Also, the proteins of Mw 28 KDa and Mw 49KDa disappeared in Summary 162 sensitive varieties (Giza 129) and appeared in tolerant varieties after 24 hour and 1st week from salt treatments respectively. 3- Proline is a type of proteins play an important role in a biotic stress as draught and salinity so we determined the concentration of proline formed in studied varieties under different concentration of NaCl, from results we found that Giza 2000 and Wadi Sedr formed a high concentration of proline under salt stress this explain why this two varieties are tolerant to salt stress while Giza 129 (sensitive cultivars) form low concentration from proline. 4- In the present investigation, BADH-1 gene expression was determined by Real Time PCR, then this gene was isolated from genomic DNA and cDNA from the most tolerant barley (Giza 2000 and Wadi Sedr) and sensitive barley Giza 129 cultivar, then sequencing of this gene was performed and it was aligned in GenBank. This nucleotide sequences were translated into amino acid sequences then these amino acid sequences were aligned in GenBank, also the 3D of BADH-1 enzyme were determined. These isolated genes were submitted in GenBank under accession number KX433169, KX342849, KX342850, KX342851, KX433170 and KX433171. from Agro-morphological, molecular and biochemical studies, the three studied landraces could be discriminated and identified, they are more similar to Giza 2000 cultivars. While from studing the effect of salinity on three landraces, we found that Wadi Sedr landrace is near to Giza 2000 cultivar. Summary 162 from this study, we recommended cultivating the more tolerant varieties (Giza 2000 and Wadi Sedr) on salin soil within the salinity range we used in this studies |