Differential Expression of miRNAs in Sorghum bicolor under Drought and Salt Stress

The regulatory mechanisms of drought and salt-associated miRNAs have not been fully understood in Sorghum bicolor. In this study, we investigated the effect of salinity stress (200 and 300 mM NaCl) and drought stress at pre- and post-flowering stages on the expression pattern of small regulatory RNAs in six Sorghum genotypes using semi-quantitative reverse transcriptase PCR (RT-qPCR). The results indicated that both drought and salt stresses altered the expression pattern of miRNAs in a dose-dependent manner. However, each miRNA responded to drought and salt stress in a different pattern among the six sorghum genotypes. miR156, miR167, miR168 and miR399 give different expressions levels compared to other studied miRNAs which may attribute to the adaption of sorghum to drought and salt stress and are good candidates for improving sorghum by transgenic technology.

Heterotic Effect, Combining Ability and Significance of Synthetics over Line Cultivars in Faba Bean (<i>Vicia faba</i>L.) Grown under Semi-Arid Zones

The aim of this study was to investigate the amount of heterosis and performance of faba bean synthetic cultivars compared to line cultivars under semi-arid conditions. Five inbred lines in at least S6 generation were developed and used to develop F1s hybrid (in all possible combination excluding reciprocal), lines mixtures (Syn-0) and synthetic generations of Syn-1. Evaluation of the entries showed the lines to have high general and specific combining ability, high yield and high average degree of cross-fertilization (0.36);hetrosis relative to mid-parent for yield was 67%. Lines mixture from four inbred lines (Hudeiba/93, Bassabier, Ed-Damar and Shabah) gave the highest yield of 3.40 t/ha for Syn-0 and 3.96 t/ha for Syn-1. Compared to the average yield t/ha of the pure stand of the four lines (3.11 t/ha), the increase in yield of was 9% in sy-0 and 27% in Syn-1. Compared to the individual yield t/ha of the pure stand of the lines, the performance of Syn-0 surpassed that of the individual pure stands of the linesby 14% for Hudiaba/93 and Bassabier and 4% for Ed-Damar and 7% for Shabah, whereas the increase in performance of Syn-1 compared to pure stand of the lines was 32%, 25% and 21%, respectively. The results confirm the previous knowledge on yield increase with successive syn-generations in faba bean due to the effects of heterogeneity and heterozygosity. Such results could be used as a base for an effective breeding program for improvement of yield of faba bean grown under the semi-arid zones.

Impact of Bee Pollination on Yield of Faba Bean (<i>Vicia faba</i>L.) Grown under Semi-Arid Conditions

The effect of honeybee (Apis mellifera carnica) on yield was investigated in open-pollinated faba bean cultivars and three inbred generations produced from them (once-selfed, twice-selfed, and thrice-selfed). All entries were grown in cages under two pollination conditions: presence of bees (cross-pollination) or absence of bees (self-pollination). The open-pollinated generations gave the highest performance in the presence and absence of bees. In the presence of bees, the open-pollinated and their inbred entries gave higher performance in all of the studied traits than in the absence of bees;the average improvement in yield and its components was 22%. The highest improvement percentage in yield performance was shown by more inbred entries (thrice-selfed > once-selfed), indicating that in faba bean populations, the performance of inbred generations was chiefly associated with the tripping of flowers, which is usually governed by successfully fertilized flowers, i.e., plants result from selfing in faba bean population needs to be visited by pollinating insects (bees) to set more seeds. It concluded that honeybee has an important role in increasing faba bean yield in semi-arid conditions;hence, it is important to provide a pollinator friendly environment for their foraging places and nesting sites to secure food supply.

Genetic Diversity in the Semi-Arid Grown Cowpea(<i>Vigna unguiculata</i>L. Walp)Accessions Using Morphological and Molecular Characterization

Assessment of genetic diversity of the indigenous crop accessions is extremely important for breeders to identify potential parents in cross-breeding programs. Fourteen cowpea accessions collected from different parts of Sudan were used for characterization at morphological and molecular levels. The seeds of the accessions were sown in the field using a randomized complete block design with three replicates. Sixteen morphological descriptors (9 qualitative and 7 quantitative) and 20 Random Amplified Polymorphic DNA (RAPD) markers were used for characterization of the accessions. The results of morphological data revealed considerable variability within and between state’s accessions. Some morphological traits revealed similarity between accessions from different states. Among the 20 RAPD markers used, 18 were polymorphic. A total of 379 polymorphic patterns were generated;polymorphic information content (PIC) ranged from 0.63 to 0.98 with an average of 0.9. The number of fragment detected ranged from 2 for OPL-11 to 51 for OPY-2 with an average of 26.06/primer and 27.07/genotype. One to five (1 - 5) unique fragments of different sizes were detected for particular accessions, which may provide a valuable resource for breeding superior cowpea cultivars in Sudan and other semi-arid zones. Genetic similarity was ranged from 0.02 to 0.47 with an average of 0.25. Highest genetic similarity was between genotypes HSD-2966 and HSD-2967 and between genotypes HSD-5131 and HSD-5627 and the lowest was between HSD-5131 and HSD-5861 followed by that between HSD-2976 and HSD-29130 accessions. The study recommends the combination of morphological and molecular data for more efficient genetic diversity assessment and management.