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Tomato (Lycopersicon esculentum Mill.) are considered major and important globally vegetable crops and in Egypt in particular. Tissue culture techniques have encouraged the utilization of mutation methods in crop improvement. The mutation induction in vegetative crops through tissue culture may be the optimal method to improve these crops. Induced genetic variation in tomato plantlets by using gamma radiation and identified these changes through SCoT and ISSR markers. Egyptian tomato cultivar Idkawy explant was cultured onto MS medium supplemented with 0.2 mg-l BAP. The resulted plantlets were irradiated with γ radiation doses (50, 100, 150, 200 or 250 Gy). The survival, growth rate, and mean of shoot length were decreased with increasing gamma radiation dose. The irradiated plantlets survival percentages were ranged from 78.75% to (50 Gy) and 18.75% to (250 Gy), whereas, the shoot length decreased by a rate of 2.71 cm for the dose (50 Gy) and 1.2 cm for dose (250 Gy). Genetic diversity was evaluated by SCoT and ISSR markers using ten primers for each. It was noticed that the polymorphism percentage mean of SCoT marker (60.53%) is higher than the ISSR marker (39.6). The PIC values average for both markers SCoT and ISSR were 0.429 and 0.347, as well, MI values were 0.345 and 0.156, respectively. On the other hand, the effective no. of alleles (Ne), Nei’s genetic diversity (H) and Shannon’s information index (I) parameters, it was found that the dose 100 Gy caused the highest genetic variation compared with other doses using SCoT marker, however, in ISSR marker was dose of 150 Gy the highest dose for induced genetic variation. The obtained results demonstrate that SCoT marker was more accurate and efficient than ISSR marker for distinguishing and genetic variation analysis of irradiated tomato plantlets. The relationships within treatments were assessed through cluster analysis (UPGMA) based on SCoT and ISSR analysis.

Haploid plants of Nicotiana alata were cultured in vitro on MS medium with IAA + KIN. The resulting plantlets were irradiated using gamma radiation doses of 10, 15, 20 and 25 Gy. Single node pieces were cut and transferred onto fresh MS medium. Gamma radiation doses caused the death of 9% and up to 28% of explants. NaCl concentrations caused the death of 8% up to 36% of explants, while the combined effect between gamma radiation doses and salinity had an impact suffused on the percentage of survival. The combined effect of gamma radiation doses 20 Gy and 25 Gy on NaCl concentrations of 100, 150 and 200 mM were deadly. Even more, the combined effect of gamma radiation doses and salinity had a severe negative impact on both the proline content and total soluble protein. Random amplified polymorphic DNA (RAPD) analysis was used to determine the degree of genetic variation in treated haploid Nicotiana alata plants. Total genomic DNAs from different haploid plantlets treated were amplified using five arbitrary primers. Two hundred and seventy bands were detected from plantlets irradiated with doses of 15, 20 and 25 Gy, with polymorphic band number 226 (83.7%). The total number of bands resulted from plant grew on 150 mM and 200 mM NaCl were 260 bands with polymorphic bands 185 (85.6%). However, the total number of bands produced from combined effects between gamma rays and salinity (20 Gy X 50 mM NaCl, 20 Gy X 100 mM NaCl and 25 Gy X 50 mM NaCl) were 270, with polymorphic band number 231 (85.5%). High similarity between treatments was revealed. Treatments relationships were estimated through cluster analysis (UPGMA) based on RAPD data.

Nicotiana alata anthers cultured on different modified media based on MS, MT and N were used to obtain haploid plants through direct and indirect ways. The haploid plants resulting on MS medium ranged from 52% - 80%, on MT medium ranged from 32% - 52% and on N medium ranged from 28% - 44%. Accordingly, the best medium used for haploid induction was MS supplemented with 0.2 mgl-l NAA + 0.5 mgl-l KIN. On the other hand, MS medium supplemented with 0.4 mgl-l NAA + 0.5 mgl-l KIN or 1.0 mgl-l BAP + 0.5 mgl-l NAA were the best mediums for callus induction and plant regeneration, respectively. Morphologically, the leaf size, stem highest and diameter, flower size and diameter, anther length and number were about 67% of the diploid plants growth. Irradiated anthers with doses of 0, 2.5, 5, 7.5, 10, 15, 20 and 25 Gy caused reducing the number of haploid plants with increasing gamma radiation dose. For the haploid plants irradiated with same doses, the mortality percentage of bud survival was increasing with increasing gamma radiation dose. The irradiated callus with doses of 0, 5, 10, 15 and 20 Gy was affected negatively on growth rate and morphology. Proline content in irradiated plantlets increased with increasing gamma radiation dose. As well, total soluble protein content was increased with gamma irradiation up to 10 Gy. However, the higher doses caused a severe decrease of total soluble proteins. The production of proline and total soluble proteins in haploid plants were 48.6% and 69.5%, respectively comparing with diploid plants.

Nicotiana alata anthers cultured on different modified media based on MS, MT and N were used to obtain haploid plants through direct and indirect ways. The haploid plants resulting on MS medium ranged from 52% - 80%, on MT medium ranged from 32% - 52% and on N medium ranged from 28% - 44%. Accordingly, the best medium used for haploid induction was MS supplemented with 0.2 mgl-l NAA + 0.5 mgl-l KIN. On the other hand, MS medium supplemented with 0.4 mgl-l NAA + 0.5 mgl-l KIN or 1.0 mgl-l BAP + 0.5 mgl-l NAA were the best mediums for callus induction and plant regeneration, respectively. Morphologically, the leaf size, stem highest and diameter, flower size and diameter, anther length and number were about 67% of the diploid plants growth. Irradiated anthers with doses of 0, 2.5, 5, 7.5, 10, 15, 20 and 25 Gy caused reducing the number of haploid plants with increasing gamma radiation dose. For the haploid plants irradiated with same doses, the mortality percentage of bud survival was increasing with increasing gamma radiation dose. The irradiated callus with doses of 0, 5, 10, 15 and 20 Gy was affected negatively on growth rate and morphology. Proline content in irradiated plantlets increased with increasing gamma radiation dose. As well, total soluble protein content was increased with gamma irradiation up to 10 Gy. However, the higher doses caused a severe decrease of total soluble proteins. The production of proline and total soluble proteins in haploid plants were 48.6% and 69.5%, respectively comparing with diploid plants.

In many fungal species, cell growth and morphology, thermo- and osmotolerance are regulated by mitogen-activated protein kinase (MAPk) cascades. Ste11p is a MAP kinase kinase kinase, which plays a central role in various pathways in Saccharomyces cerevisiae. Here we describe ASTE11, an STE11 homologue from Arxula adeninivorans, an imperfect, dimorphic, but nonpathogenic and extremophilic yeast. ASTE11 lacks introns, and codes for a protein of 824 amino acids with a predicted molecular weight of 91.6 kDa. The gene is constitutively expressed at low levels, but is induced by high-salt stress. To facilitate functional analysis of ASTE11, disruption and overexpressing mutants were constructed. The phenotypes of these strains indicate that Aste11p is involved in regulating aspects of cell wall structure and form, but is dispensable for adaptation to hypertonic stress. Despite its structural homology to STE11, ASTE11 cannot complement the mating defect of S. cerevisiae ste11 mutants. These findings emphasize that, although components of MAPk pathways are conserved among yeasts, they often operate in different contexts in different species.

The yeast Arxula adeninivorans provides an attractive expression platform and can be exploited as gene source for biotechnologically interesting proteins. In the following study, a striking example for the combination of both aspects is presented. The transaldolase-encoding A. adeninivorans ATAL gene, including its promoter and terminator elements, was isolated and characterized. The gene includes a coding sequence of 963 bp encoding a putative 321 amino acid protein of 35.0 kDa. The enzyme characteristics analyzed from isolates of native strains and recombinant strains overexpressing the ATAL gene revealed a molecular mass of ca. 140 kDa corresponding to a tetrameric structure, a pH optimum of ca. 5.5, and a temperature optimum of 20 degrees C. The preferred substrates for the enzyme include D-erythrose-4-phosphate and D-fructose-6-phosphate, whereas D-glyceraldehyde is not converted. The ATAL expression level under salt-free conditions was observed to increase in media supplemented with 5% NaCl rendering the ATAL promoter attractive for moderate heterologous gene expression under high-salt conditions. Its suitability was assessed for the expression of a human serum albumin (HSA) reporter gene.