Vitamin-C content (VCC) was evaluated in 74 guava landraces using direct titration method with iodine during two seasons. Results showed that the highest value of VCC was 284.0±1.33, while the lowest VCC was 152.83±1.83 with an average of 221.26±3.17 mg/100g fresh weight. Analysis of variance showed the presence of highly significant differences among the tested landraces, as well as the interaction between landraces and seasons. Data of VCC showed normal distribution with high values of both broad sense heritability (0.97) and genetic advance (78.49) indicating high ability for selection. On the other hand, molecular analysis was performed using two molecular markers, i.e. sequence related amplified polymorphism (SRAP) and inter sequence simple repeats (ISSR) to determine unique and specific bands for high or low VCC. SRAP was more informative than ISSR and was able to generate 12 specific bands. Among these bands, 10 bands were specific for bulked DNA of landraces with high VCC, while the other two bands were specific for low VCC. However, ISSR only showed four bands where all of them were specific for low VCC. Results of this study gave good information for genotype selection for high VCC which could be used in guava breeding programs and/or biotechnological approaches. In addition, the specific bands generated by SRAP might assist in rapid screening for genotypes with high VCC, which could be identified in seedling or graft stage, therefore this would save time in a plant with long juvenile period like guava. Furthermore, these bands would be analyzed by sequencing in subsequent studies to locate related genome regions.

Forty landraces of guava were subjected to drought tolerance evaluation based on in vitro polyethylene glycol (PEG) treatment. Nodal stem segments with lateral buds were used as explant. Five concentrations (i.e. 0, 4, 6, 8 and 10%) of PEG were tested, among which the optimum concentration for screening was determined as 8%. Analysis of variance showed highly significant variation among the tested landraces, concentrations of PEG and the interaction between them in the percentage of response (%R), number of shoot per explant (NSE) and drought susceptibility index. The average percentage of reduction due to PEG treatment was 48.30 and 52.57% for the %R and NSE, respectively. Heritability and genetic advance were increased due to drought stress for %R, while they were decreased for NSE, indicating that %R was more related to drought stress than NSE. The molecular analysis of the highest and lowest responsive landraces was performed using sequence related amplified polymorphism (SRAP) and inter-simple sequence repeats (ISSR). Both markers were effective in discriminating the tested landraces and completely separated them into two clusters related to %R under PEG. ISSR showed a higher percentage of polymorphism, polymorphic information content and diversity index compared with SRAP. However, SRAP was more effective than ISSR in showing a higher primer resolving power and a number of unique specific bands for drought tolerance and susceptibility. Drought in vitro evaluation method established here is effective, inexpensive and manageable in genotype screening for drought tolerance in guava and could be used in other woody plant species.

Forty landraces of guava were subjected to drought tolerance evaluation based on in vitro polyethylene glycol (PEG) treatment. Nodal stem segments with lateral buds were used as explant. Five concentrations (i.e. 0, 4, 6, 8 and 10%) of PEG were tested, among which the optimum concentration for screening was determined as 8%. Analysis of variance showed highly significant variation among the tested landraces, concentrations of PEG and the interaction between them in the percentage of response (%R), number of shoot per explant (NSE) and drought susceptibility index. The average percentage of reduction due to PEG treatment was 48.30 and 52.57% for the %R and NSE, respectively. Heritability and genetic advance were increased due to drought stress for %R, while they were decreased for NSE, indicating that %R was more related to drought stress than NSE. The molecular analysis of the highest and lowest responsive landraces was performed using sequence related amplified polymorphism (SRAP) and inter-simple sequence repeats (ISSR). Both markers were effective in discriminating the tested landraces and completely separated them into two clusters related to %R under PEG. ISSR showed a higher percentage of polymorphism, polymorphic information content and diversity index compared with SRAP. However, SRAP was more effective than ISSR in showing a higher primer resolving power and a number of unique specific bands for drought tolerance and susceptibility. Drought in vitro evaluation method established here is effective, inexpensive and manageable in genotype screening for drought tolerance in guava and could be used in other woody plant species.

Forty landraces of guava were subjected to drought tolerance evaluation based on in vitro polyethylene glycol (PEG) treatment. Nodal stem segments with lateral buds were used as explant. Five concentrations (i.e. 0, 4, 6, 8 and 10%) of PEG were tested, among which the optimum concentration for screening was determined as 8%. Analysis of variance showed highly significant variation among the tested landraces, concentrations of PEG and the interaction between them in the percentage of response (%R), number of shoot per explant (NSE) and drought susceptibility index. The average percentage of reduction due to PEG treatment was 48.30 and 52.57% for the %R and NSE, respectively. Heritability and genetic advance were increased due to drought stress for %R, while they were decreased for NSE, indicating that %R was more related to drought stress than NSE. The molecular analysis of the highest and lowest responsive landraces was performed using sequence related amplified polymorphism (SRAP) and inter-simple sequence repeats (ISSR). Both markers were effective in discriminating the tested landraces and completely separated them into two clusters related to %R under PEG. ISSR showed a higher percentage of polymorphism, polymorphic information content and diversity index compared with SRAP. However, SRAP was more effective than ISSR in showing a higher primer resolving power and a number of unique specific bands for drought tolerance and susceptibility. Drought in vitro evaluation method established here is effective, inexpensive and manageable in genotype screening for drought tolerance in guava and could be used in other woody plant species.

Fifty bread wheat lines were evaluated for drought tolerance and compared to six local cultivars under three water regimes (Well-watered = 0.8 Evapotranspiration (ETp), Mild drought stress = 0.6 ETp and severe drought stress = 0.4 ETp.). Eight agronomic traits were evaluated, i.e. days to heading, number of spikes/plant, 100-kernel weight (g), relative water content (%) , chlorophyll concentration (μg/cm2), grain yield/plant (g), harvest index and water use efficiency (WUE) (kg/m3) under normal and stress conditions. Analysis of variance showed highly significant variations among the tested lines. As an average of all tested lines chlorophyll concentration was the most affected trait by drought followed by grain yield per plant and WUE, while harvest index showed the lowest reduction due to drought stress. Five lines (1, 5, 11, 41 and 42) showed high performance in grain yield/plant and surpassed all local varieties under all conditions. The sequence related amplified polymorphism (SRAP) technique was used for detection of markers associated with drought tolerance. SRAP was able to discriminate between the bulked-DNA of high and low performance lines in some evaluated traits under drought. Moreover, several unique and specific bands for high- and low-bulked lines were generated exposing the efficiency of SRAP in genotyping and diversity analysis. Evaluation of WUE showed its efficiency in differentiating among the tested lines and was in agreement with SRAP analysis which showed the maximum number of specific markers when the high- and low-WUE bulks were compared unlike the other traits. The generated bands could serve preliminarily as selectable markers for drought tolerance in wheat.

Fifty bread wheat lines were evaluated for drought tolerance and compared to six local cultivars under three water regimes (Well-watered = 0.8 Evapotranspiration (ETp), Mild drought stress = 0.6 ETp and severe drought stress = 0.4 ETp.). Eight agronomic traits were evaluated, i.e. days to heading, number of spikes/plant, 100-kernel weight (g), relative water content (%) , chlorophyll concentration (μg/cm2), grain yield/plant (g), harvest index and water use efficiency (WUE) (kg/m3) under normal and stress conditions. Analysis of variance showed highly significant variations among the tested lines. As an average of all tested lines chlorophyll concentration was the most affected trait by drought followed by grain yield per plant and WUE, while harvest index showed the lowest reduction due to drought stress. Five lines (1, 5, 11, 41 and 42) showed high performance in grain yield/plant and surpassed all local varieties under all conditions. The sequence related amplified polymorphism (SRAP) technique was used for detection of markers associated with drought tolerance. SRAP was able to discriminate between the bulked-DNA of high and low performance lines in some evaluated traits under drought. Moreover, several unique and specific bands for high- and low-bulked lines were generated exposing the efficiency of SRAP in genotyping and diversity analysis. Evaluation of WUE showed its efficiency in differentiating among the tested lines and was in agreement with SRAP analysis which showed the maximum number of specific markers when the high- and low-WUE bulks were compared unlike the other traits. The generated bands could serve preliminarily as selectable markers for drought tolerance in wheat.

The sequence related amplified polymorphism (SRAP) was used to assess genetic relationship among some Musa balbisiana related accessions including wild diploid, triploid cultivar, plantains, diploid and tetraploid hybrids. A total of 74 bands were generated, of which 65 bands (87.84%) were polymorphic among the tested accessions. The average of polymorphism information content (PIC) for all primers was 0.29, while the average of diversity index (DI) was 0.73. Results showed the SRAP efficiency in grouping the tested accessions and exposing minimum differences among genotypes. Interestingly, the wild diploid accessions were separated into two groups, in which BB-CICY, Tani, Cameron and Singapuri grouped together with the triploid cultivar “Lep Chang Kut”, while the other diploid accessions, i.e. Butuhan, Pisang Batu and BB-545, formed the second group near to plantains and hybrids. These findings were subsequently supported by the identification of some specific bands generated by SRAP, which were existed in all B genome contained accessions with the exception of Butuhan, Pisang Batu and BB-545. The results suggested that these accessions may have recombinant chromosomes of A and B genomes or they are mislabeled. The identification of the specific bands for B genome found in this study provided markers linked to chromosomes 2, 8 and 11, which could be helpful in discriminating banana and plantain cultivars. Specific primers were designed from sequences of some specific bands, among which a 256bp fragment was successfully amplified, and was able to distinguish between acuminata and balbisiana accessions. Moreover, the information herein could be important in Musa basic breeding program, identification of mislabeled accessions and germplasm management and conservation.

A reproducible method for extraction of high-quality genomic DNA (gDNA) suitable for application in several PCR-based methods was developed after modifications to the Dellaporta method. Changes to the extraction buffer include the use of a higher concentration of NaCl, substitution of β-mercaptoethanol with sodium-metabisulfite, and the use of polyethylene glycol for DNA precipitation. Compared to the original method and two other protocols tested, our improved protocol resulted in the isolation of a good yield and purity of gDNA. The content of extracted DNA was spectrophotometrically evaluated, and the quality was analyzed by Amplified Fragment Length Polymorphisms (AFLP). AFLP profiles of the DNA obtained with our protocol were comparable to those of a commercial kit for plant DNA extraction. The potential of this improved method relies on its successful use with different molecular markers using gDNA extracted from fresh and frozen tissues of a variety of vascular plants, including banana in this paper, and proven in wheat, guava, sugarcane, and bean, as well as from microalgae. Therefore, the new protocol is an adequate, convenient and economical choice for use and study of various fields of genomics.

Phosphorus applications (0.6, 1.2 and 1.8 gm/kg soil) were applied to six leguminous tree species; Acacia laeta, Acacia abida, Acacia nilotica, Acacia farnesiana, Tamarindus indica and Haematoxylum campechianum to define the suitable P rate for favorable growth. The heaviest roots in average of both seasons; fresh and dry were obtained from T. indica. The thickest and heaviest shoot were resulted from A. laeta. The longest roots recorded by A. nilotica and A. farnesiana. The maximum N and P contents were obtained by T. indica. The other species achieved intermediate levels of N and P. In relation to P application, a rate of 1.2 gm/kg of phosphorus was the best for shoot diameter and root length, meanwhile, 1.8 gm/kg increased fresh and dry weight of both shoots and roots. Leaf content of N was increased with increasing P from 0.6 to 1.8 gm/kg. Phosphorus addition at 1.2 gm/kg was more effective in accumulation of P concentration.