In vitro effect of different cytokinin types (BAP, TDZ) on two different Ocimum basilicum cultivars explants

Ocimum basilicum L. (sweet basil) is an economically and ethnobotanically important aromatic, medicinal, ornamental and culinary herb, with a very wide gene pool, that is sensitive to cold and prone to several plant pathogens that can demolish harvest and lessen yield. In this research, the effects of BAP (6-Benzylaminopurine) and TDZ (Thidiazuron) on different genotypes for in vitro cloning were determined, in order to provide a detailed protocol guide concerning Ocimum basilicum L. propagation. The results from the O. basilicum seed propagations revealed that the best condition for the secondary shoot growth is with 5.0 mg/l TDZ or 1.5 mg/l BAP on all types of explants except the root, the secondary root growth can be obtained on all types explant with any BAP concentration and all cytokinins can induce callus on all types of explants. On the whole, it shows that multiple secondary shoot induction and regeneration in Ocimum basilicum L. is regulated by appropriate cytokinin concentration.

Lepidozia bragginsiana, a new species from New Zealand (Marchantiopsida)

Molecular and morphological data support the recognition of a new Lepidozia species related to L. pendulina and also endemic to New Zealand, which we dedicate to Dr John Braggins. Lepidozia bragginsiana can be distinguished from closely related and other similar species by its bipinnate branching, the narrow underleaf lobes, typically uniseriate toward their tip on both primary and secondary shoots, the asymmetric underleaves on primary shoots that are usually narrower than the stem and also possess basal spines and spurs, the production of spurs and spines, or even accessory lobes, on the postical margin of primary and secondary shoot leaves; and by the relatively small leaf cells with evenly thickened walls. Lepidozia bragginsiana is an inhabitant of hyper-humid forest habitats where it occupies elevated microsites on the forest floor. A lectotype is proposed for L. obtusiloba.

Rose Phytoene Desaturase Gene Silencing by Apple Latent Spherical Virus Vectors

We have succeeded in establishing a virus-induced gene silencing (VIGS) of rose using Apple latent spherical virus (ALSV) vectors. An ALSV infection on rose did not cause any symptoms like those observed on other plant species and grew healthy. We have cloned and sequenced the phytoene desaturase (PDS) gene in wild rose, then used its fragment for silencing the rose internal PDS gene. The silencing phenotypes such as the highly uniform photo-bleached phenotype with PDS inhibitions were observed on the upper leaves of primary shoots and on a secondary shoot of R. rugosa for more than 5 months. ALSV vectors seemed useful for analyzing gene function and for the molecular breeding of rose.

Growth and Branching Responses of Portulaca grandiflora to Foliar Applications of Chemical Growth Regulators

During container production of portulaca, growth of long, prostrate, sparsely branched stems makes handling of plants difficult, and reduces their commercial appeal. Growers prefer to minimize shoot elongation while increasing branching to provide a full, compact plant. The objectives of this study were to evaluate growth regulators for promotion of branching and inhibition of stem elongation. Container-grown plants ≈21 cm in diameter were treated with sprays of ProShear (benzylaminopurine) at 62.4, 125, and 250 ppm; Promalin (benzyaminopurine + gibberellins 4+7) at 125, 250, and 500 ppm; Atrimmec (dikegulac) at 250, 500, and 750 ppm; and Florel (ethephon) at 250, 500, and 750 ppm. These treatments were compared with untreated controls in a randomized complete-block design. Main shoot lengths were measured at 16, 31, and 51 days after treatment (DAT). Numbers of new shoot breaks were counted 16 DAT. The growth habit, that is, tendency to grow upright or prostrate, was also evaluated 16 DAT. The most-effective material for retarding primary shoot elongation and for stimulating secondary shoot development was ProShear. At 16 DAT, 250 ppm ProShear reduced shoot elongation by 25% compared to control plants. This treatment also increased the number of secondary shoot breaks by 143%. Promalin increased the number of new shoot breaks, but it also increased the lengths of all shoots. High rates of Florel and Promalin caused shoots to grow predominantly upright rather then prostrate. ProShear, however, caused more prostrate growth as rate increased.

Clopyralid Effects on Shoot Emergence, Root Biomass, and Secondary Shoot Regrowth Potential of Canada Thistle (Cirsium arvense)

The root fresh weight of intact Canada thistle plants was greater than that of decapitated plants 2 months following soil surface treatment with clopyralid at 140 g ai/ha. Nevertheless, secondary shoot regrowth potential was reduced to the same extent for both intact and decapitated plants after clopyralid treatment. Soil-applied clopyralid did not reduce root biomass as much as it reduced secondary shoot regrowth potential from adventitious root buds. Increasing the clopyralid rate from 11 to 1120 g/ha progressively reduced the total number of emerged shoots more than root fresh weight 2 months after treatment of decapitated Canada thistle. Increasing the clopyralid rate also reduced the regrowth potential of secondary shoots from root buds proportionately more than it reduced root biomass. Secondary shoots emerging through a surface layer of soil treated with clopyralid at 140 g/ha absorbed phytotoxic amounts of clopyralid. Secondary shoot numbers were not reduced after emerging through an activated charcoal layer into herbicide-treated soil, but they were deformed and their dry weight was reduced as was later secondary shoot regrowth potential.

Toxicity, Absorption, Translocation, and Metabolism of Foliar-Applied Chlorimuron in Yellow and Purple Nutsedge (Cyperus esculentusandC. rotundus)

Greenhouse and laboratory experiments were conducted to study the activity of foliar-applied chlorimuron in yellow and purple nutsedge. Foliar-applied chlorimuron caused injury to both yellow and purple nutsedge at rates as low as 5 g ai/ha. Visible injury increased as rates increased from 5 to 20 g/ha at all weekly evaluation dates. At 28 days after application, there was 84% control of yellow and 100% control of purple nutsedge from 20 g/ha of chlorimuron. In both species, all rates of chlorimuron reduced shoot dry weight, inhibited secondary shoot production, and inhibited resprouting of parent tubers attached to treated plants. Over 92% of the applied label was recovered, when 15 μl of 3.46 mM14C-chlorimuron solution containing 0.18 μCi was applied to a 1 cm2area in the middle of the fourth fully expanded leaf. Over 12% of the total14C applied was absorbed, with over 15% of that being translocated within 1 day after application in both species. More than 76% of the absorbed14C in yellow nutsedge and 72% in purple nutsedge remained in the treated area. In both species, basipetal transport was limited. Analysis of plant tissue extracts by thin-layer chromatography indicated slow degradation of chlorimuron in both species. Susceptibility of yellow and purple nutsedge to chlorimuron appears to be due to the rapid absorption and translocation rates in relationship to the slow degradation rate of the active parent compound.

A comparative study of initiation and development of embryogenic callus from haploid embryos of several barley cultivars. I. Developmental state of embryo explants and callus potential

Six cultivars of barley (‘Akka’, ‘Bruce’, ‘Klages’, ‘Leger’, ‘Perth’, and ‘York’) were compared for their ability to produce haploid embryos competent to produce embryogenic haploid callus. The capacity to generate such callus from scutellar epidermal cells is different among these cultivars and appears to be correlated with the developmental state–age of the embryo and associated with a rapid growth period. Histological examination of 12-, 14-, and 16-day-old embryos confirmed the meristematic nature of the callus-initiating cells and produced results which correspond well with results obtained from cultures of other similar embryos. Variability among cultivars in embryo development, root initiation from callus, and primary and secondary shoot regeneration was also identified.