Genotype dependent callus induction and shoot regeneration in sunflower (Helianthus annuus L.)

This study aims to observe the effect of genotype, hormone and culture conditions on sunflower (Helianthus annuus L.) callus induction and indirect plant regeneration. Calli were obtained from hypocotyl and cotyledon explants of five different sunflower genotypes; Trakya 80, Trakya 129, Trakya 259, Trakya 2098 and Viniimk 8931, which are commercially important for Turkey. Seeds germinated on Murashige and Skoog (MS) media contained no hormones. Hypocotyl and cotyledon explants were cultured on MS media supplemented with 1 mg/l 2,4-D (2,4-dichlorophenoxy acetic acid) and different percentage of callus inductions were obtained. Calli were cultured on MS + 1 mg/l BA (6-benzylaminopurine) and 0.5 mg/l NAA (-naphthalene acetic acid). Some genotypes showed high regeneration response while others showed lower on the same media with hypocotyl and cotyledon derived calli. This study showed that genotypic differences affect callus induction and plant regeneration in sunflower tissue culture studies

Inhibition of NOS- like activity in maize alters the expression of genes involved in H2O2 scavenging and glycine betaine biosynthesis

Nitric oxide synthase-like activity contributes to the production of nitric oxide in plants, which controls plant responses to stress. This study investigates if changes in ascorbate peroxidase enzymatic activity and glycine betaine content in response to inhibition of nitric oxide synthase-like activity are associated with transcriptional regulation by analyzing transcript levels of genes (betaine aldehyde dehydrogenase) involved in glycine betaine biosynthesis and those encoding antioxidant enzymes (ascorbate peroxidase and catalase) in leaves of maize seedlings treated with an inhibitor of nitric oxide synthase-like activity. In seedlings treated with a nitric oxide synthase inhibitor, transcript levels of betaine aldehyde dehydrogenase were decreased. In plants treated with the nitric oxide synthase inhibitor, the transcript levels of ascorbate peroxidase-encoding genes were down-regulated. We thus conclude that inhibition of nitric oxide synthase-like activity suppresses the expression of ascorbate peroxidase and betaine aldehyde dehydrogenase genes in maize leaves. Furthermore, catalase activity was suppressed in leaves of plants treated with nitric oxide synthase inhibitor; and this corresponded with the suppression of the expression of catalase genes. We further conclude that inhibition of nitric oxide synthase-like activity, which suppresses ascorbate peroxidase and catalase enzymatic activities, results in increased H2O2 content

Direct plant regeneration from hypocotyl and cotyledon explants of five different sunflower genotypes (Helianthus annus L.) from Turkey

This study aims to establish plant tissue culture and regeneration systems of five different sunflower (Helianthus annuus L.) genotypes: Trakya 259, Trakya 80, Trakya 129, Trakya 2098 and Viniimk 8931, which are commercially important for Turkey. Plant tissue culture systems were established on Murashige and Skoog (MS) media supplemented with various plant growth regulators using hypocotyl and cotyledon explants. The highest shoot regeneration was observed using hypocotyl explants with Trakya 259 genotype (40 %) on MS media supplemented with 1 mg/l BAP (6-benzylaminopurine) and 0.5 mg/l NAA (a-naphthalene acetic acid). Hypocotyl explants from other genotypes showed regeneration efficiencies as followed: Trakya 80, 33 %; Trakya 129, 29 %; Trakyu 2098, 22 % and Viniimk 8931, 19 %. Shoot regeneration efficiencies with the cotyledon explants on the same medium were lower in comparation with hypocotyl explants as followed: Trakya 129, 20 %; Trakya 2098, 10 % and Viniimk 8931, 9 %. In addition, two genotypes (Trakya 259 and Trakya 80) were non-responsive on the same media with cotyledon explants. All of the regenerated shoots were rooted on MS media supplemented with 1 mg/l IBA (indol-3-butiric acid). The results obtained in this study will be useful for the improvement of gene transfer systems to these commercially important sunflower genotypes