No abstract

No abstract

We report for the first time that expression of potato PR10a gene in faba bean causes enhanced tolerance to drought and salinity. Grain legumes such as soybean (Glycine max L. Merrill), pea (Pisum sativum L.) and faba bean (Vicia faba L.) are staple sources of protein for human and animal nutrition. Among grain legumes, faba bean is particularly sensitive to abiotic stress (in particular osmotic stress due to lack of water or enhanced soil salinity) and often suffers from severe yield losses. Many stress responsive genes have been reported with an effect on improving stress tolerance in model plants. Pathogenesis-related proteins are expressed by all plants in response to pathogen infection and, in many cases, in response to abiotic stresses as well. The PR10a gene isolated from the potato cultivar Desiree was selected for this study due to its role in enhancing salt and/or drought tolerance in potato, and transferred into faba bean cultivar Tattoo by Agrobacterium tumefaciens-mediated transformation system based upon direct shoot regeneration after transformation of meristematic cells derived from embryo axes. The transgene was under the control of the constitutive mannopine synthase promoter (p-MAS) in a dicistronic binary vector, which also contained luciferase (Luc) gene as scorable marker linked by internal ribosome entry site elements. Fertile transgenic faba bean plants were recovered. Inheritance and expression of the foreign genes were demonstrated by PCR, RT-PCR, Southern blot and monitoring of Luciferase activity. Under drought condition, after withholding water for 3 weeks, the leaves of transgenic plants were still green, while non-transgenic plants (WT) wilted and turned brown. Twenty-four hours after re-watering, the leaves of transgenic plants remained green, while WT plants did not recover. Moreover, the transgenic lines displayed higher tolerance to NaCl stress. Our results suggested that introducing a novel PR10a gene into faba bean could be a promising approach to improve its drought and salt tolerance ability, and that MAS promoter is not only constitutive, but also wound-, auxin/cytokinin- as well as stress-inducible.

No abstract

The present study was carried out for developing an efficient in vitro callus induction and plant regeneration system in four different tomato genotypes (Solanum lycopersicum Mill., previous name: Lycopersicon esculentum), Advantage II, Edkawy, Castle Rock and Super Strain B, using hypocotyl and cotyledon explants. The effects of two cytokinins, BA (benzyl adenine) and Kin (kinetin), on callus induction and plant regeneration frequency were investigated when added to MS medium in combination at varying concentrations. All concentrations of the two cytokinins were suitable for callus induction and plant regeneration. The frequency of callus induction and plant regeneration from both cotyledon and hypocotyl explants reached 100% for all tested genotypes. Cotyledons produced a higher average number of shoots per explants than hypocotyls for all the genotypes in the five concentrations of combined cytokinins. The average number of shoots per explant in Super Strain B was found to be the highest (42 and 60 for the hypocotyl and cotyledon explants, respectively). Supplementing MS medium with 1.0 mg L−1 kinetin and 1.0 mg L−1 benzyl adenine was found to be optimum for producing the highest number of shoots per explant from hypocotyls and cotyledons in the tomato genotypes investigated. The proposed medium showed a significant superiority over the reference media.

Rice is the most important food crop for the developing world. Hence, identifying rice genotypes to drought tolerance for using as donors in breeding is one of the most important challenges for rice research. Therefore, Molecular markers are useful tools to determine genetic diversity and identifying rice genotypes to drought tolerance. In the present study, A number of 41 rice genotypes with different drought tolerance from different geographic locations were evaluated for genetic diversity by using 15 SSR markers. A total of 68 alleles were detected of which 61(89.79%) were polymorphic. The number of alleles detected by a single marker varied from 2 to 8 alleles with an average of 4.71 alleles per locus. The polymorphic information content (PIC) values ranged from 0.07 (RM219) to 0.80 (RM263) with an average of 0.52. Genetic similarity coefficients of pair wise comparisons were estimated on the basis of the polymorphic microsatelite loci ranged from 0.23 to 0.91 indicating a wide range of genetic variation present among the studied genotypes. It was determined that the primers RM20A, RM302, RM212 and RM286 could be useful for selecting drought tolerant lines through MAS approach. The most significant application of these identified major QTLs for drought tolerance is to collect those favorable alleles into elite local line through marker assisted breeding. The results indicated the ability of SSR markers to identify the allelic diversity and genetic variation among the studied rice genotypes. These results recommended for using this material in future breeding programs to provide important source of genetic diversity for drought tolerance in rice.

Microbial contamination is a common problem that causes significant losses in plant micropropagation systems. The present study reports on the identification and control of bacterial contaminants in banana in vitro cultures. Twelve isolates belonging to Bacillus pumilus (S2), Bacillus subtilis (R2 and M4), Geobacillus stearothermophilus (S1, S3, S4, P2, M3 and R3) and Paenibacillus spp. (P1, R1 and M2) were identified by sequencing of 16S rRNA, gyrA or gyrB genes. Antibiotic susceptibility testing was performed with the disk diffusion method on bacterial isolates using 36 antimicrobial agents. Some antibiotics, notably Ticarcillin, Penicillin, Ampicillin, Cefazolin and Imipenem, had a broader range of bactericidal activity than others did. When contaminated axillary shoot cultures of banana were treated with 100 or 200 mg·L−1 of ticarcillin, ampicillin or penicillin the bacteria were eliminated, but a reduction in shoot multiplication and growth was observed. These findings contribute to minimizing the losses in the commercial micropropagation of banana.

Genus Carissa represents several species that are reported to be of great phyto-medicinal and ethnopharmacological value. However, Carissa macrocarpa is relatively understudied. Furthermore, environmental conditions such as seasonal changes are known to affect the phytochemical composition of medicinal plants. Therefore, this study aimed to investigate the phytochemical composition and biological activity of the leaf extracts of C. macrocarpa in the summer and winter seasons. The phytochemical screening of C. macrocarpa leaves showed positive results for a variety of phytochemicals, such as alkaloids, tannins, phenols, naphthoquinones, flavonoids, saponins, steroids, proteins, carbohydrates, mucilage, gum and resin. The methanolic extract was evaluated for its antibacterial activity against Escherichia coli and Staphylococcus aureus using the agar well diffusion method. The winter leaf extract was distinguished for its potential antibacterial activity against both bacterial strains with inhibition zones (mm) of 8.17 ± 1.04 and 6.83 ± 0.58 at 10 mg/mL. The antioxidant activity of the leaf extracts was evaluated using the 2, 2′-diphenyl-1-picrylhydrazyl (DPPH) assay. The percentage scavenging activities of the different extracts were significantly greater than that of the control. Furthermore, at 15, 30, 60, 120 and 240 µg/mL, the percentage scavenging activities of the winter methanol leaf extract were 74.65, 78.31, 85.45, 90.02 and 95.68%, and those of the summer one were 71.66, 73.57, 84.05, 88.22 and 96.28%, respectively, indicating that the methanol leaf extract had greater percentage scavenging activity in winter than in summer. In winter, the IC50 value of the methanol leaf extract (0.67 µg/mL) was lower than that of ascorbic acid (8.26 µg/mL). It is concluded that winter is the optimal season to harvest leaves of C. macrocarpa for medicinal use. To the best of our knowledge, this is the first report that relates the phytochemical composition and medicinal properties of C. macrocarpa to changes in seasons. The results obtained are promising, and this species should be further explored to decipher its pharmacological worth.