In potato the polyphenol oxidase (PPO) mediated wound-inducible browning phenotypes is one of the major drawback for food industry. In order to investigate and reduce PPO's expression for browning we obtained the potato specific PPO cDNAs using Vicia faba L. specific (Locus VVU 83274) primers and cloned them under control of the cauliflower mosaic virus 35S promoter. Transgenic potato plants (Solanum tuberosum L.) that show down expression of PPOs were obtained using Agrobacterium mediated transformation. Wounded transgenic plants with reduced PPO activity exhibited a great amount of reduced browning when compared with their control plants. Our results confirm the importance of PPO mediated phenolic oxidation in browning discoloration of potato suggesting the possibility of manipulation of PPO expression
Plant regeneration from 9 clones ofPopulus tremula representing diverse genotypes originated from Turkey, has been studied in different media, such as Murashige and Skoog's Medium (MS), Aspen Culture Medium (ACM) and Woody Plant Medium (WPM) with appropriate supplements of growth regulators. Regeneration efficiency on WPM containing 1 mg/l zeatin using stem explantsin vitro, was higher than on MS and ACM. In this system, the time required for shoot regeneration was 2 weeks, which was shorter by two weeks than that of previous reports. A strong genotype dependence was observed among the tested nine clones. The regeneration system, we describe here, did not involve the callus phase and thus was less prone to somaclonal variation. When adventitious microshoots were cultured on WPM supplemented with 0.5 mg/l or 2 mg/l indole-3-butyric acid (IBA), root formation was obtained after 1 week of culture. Adaptation of regenerated plantletsin vivo was 100%. This system for micropropagation ofPopulus tremula is expected to be suitable for studies on transformation of genes involved in lignin biosynthesis via modification of lignin content.
Retrotransposons are genetic elements that can move within the genome. They can cause mutations by inserting themselves near or within genes. They may also have an important role in the regulation of the development. Barley is an important model plant in addition to its commercial importance. Retrotransposons constitute more than 50% of the barley (Hordeum vulgare L.) genome. In this study, we used mature embryo, leaf and root tissues grown from the same barley plant, to investigate BARE1 and BAGY2 retrotransposon movements, and to analyze the expression of inner domains of BARE1-gag, BAGY2-env (envelope) and rt (reverse transcriptase), using IRAP (Inter-Retrotransposon Amplified Polymorphism) and reverse transcriptase PCR (RT-PCR) techniques, respectively. Barley seeds germinated in Petri dishes under sterile conditions for 16 h were used for mature embryo dissection and genomic DNA isolation. Genomic DNA was also isolated from the leaves and roots of 5 individual seedlings which were harvested on the 10th day of germination. IRAP-PCR was performed with each DNA template for BARE1 and BAGY2 retrotransposons. BAGY2 was found to be more stable, while BARE1 polymorphisms were observed among embryos, 10-day-old roots and 10-day-old leaves. We found 50 % similarity between the roots and the leaves, 55 % between the embryo and the roots, and 66 % between the embryo and the leaves.Different PCR products of cDNA samples from embryos, roots and leaves demonstrated that the expression profile might change among individuals. The obtained findings are expected to contribute to our understanding of the effects of epigenetic changes during barley development.
The stability of aging barley calli was investigated with the barley retroelement 1 (BARE-1) retrotransposon specific inter-retrotransposon amplified polymorphism (IRAP) technique.Mature embryos of barley (Hordeum vulgare cv.Zafer-160) were cultured on callus induction MS medium supplemented with 3 mg/L 2,4-D and maintained on the same medium for 60 days.Ten IRAP primers were used in 25 different combinations.The similarity index between 30-day-old and 45-day-old calli was 84%; however, the similarity index between mature embryos and 45-day-old calli was 75%.These culture conditions caused BARE-1 retrotransposon alterations to appear as different band profiles.This is the first report of the use of the IRAP technique in barley in an investigation of callus development.
