Thidiazuron-induced shoot organogenesis from mature leaf explants of scented Pelargonium capitatum cultivars

Shoot organogenesis from mature leaf tissues of two scented Pelargonium capitatum cultivars, ‘Attar of Roses’ and ‘Atomic Snowflake’, grown in the greenhouse, were optimized in the presence of thidiazuron (TDZ). The protocol involved preculture of leaf sections on basal Murashige and Skoog (MS) medium supplemented with 10 lM TDZ, 4.4 lM of 6-benzyladenine (BA) and 5.4 lM a-naphtaleneacetic acid (NAA) for a period of 2 weeks and followed by subculture of explants to a fresh medium containing 4.4 lM BA and 5.4 lM NAA. Frequency of regeneration reached approximately 93% for both cultivars, with the induction of more than 100 shoots per explant. Regenerated plantlets were rooted on half-strength MS medium supplemented with 4.4 mM sucrose and 8.6 lM of Indole-3-acetic acid (IAA). All regenerated shoots from both cultivars developed roots when transferred to organic soil mix, acclimatized, and successfully transferred to greenhouse conditions. When regenerated shoots were transferred to hydroponic conditions, frequency of survival was 76.2 and 61.9% for ‘Attar of Roses’ and ‘Atomic Snowflake’, respectively

Plant regeneration from leaf-derived callus cultures of Primrose (Primula vulgaris)

Efficient micropropagation of Primula species is important both for fundamental scientific studies and commercial applications. Primula vulgaris, along with other Primulaceae species, exhibits floral heteromorphy with two distinct forms of hermaphroditic flower. Studies to identify genes that control heteromorphic flower development require propagation of floral mutants, and efficient regeneration is a key requirement for plant transformation. Several species, including P. vulgaris (Huds.) cultivars and P. x polyantha hybrids are important horticultural crops in Europe, USA and Japan and semi-double/double Primula varieties offer a high-end product. Vegetative propagation of sterile double forms, and as a means to increase numbers of inbred parent plants for F1 seed production, is however, slow. Micropropagation offers the most efficient way of increasing these varieties quickly and efficiently. To date most Primula micropropagation protocols require explant material derived from in vitro grown seedlings or use floral parts as donor material with seasonal limitations. Therefore, an effective and efficient protocol was developed for in vitro regeneration of P. vulgaris via indirect organogenesis from adult leaf derived explants. Exposure of leaf explants of P. vulgaris to media containing synthetic cytokinin, thidiazuron (TDZ) and Auxin (NAA or 2,4-D) resulted in undifferentiated cell proliferation and followed by differentiated growth as shoot organogenesis. Silver nitrate improved in vitro callus growth and increased shoot regeneration further, with up to 72% of explants producing shoots. Regenerated plants developed normally and produced normal fertile flowers within 7 months. The system was also successfully applied for the micropropagation of sterile double-flowered P. vulgaris 'Sue Jervis'. The protocol reported here enables propagation of P. vulgaris without seasonal limitation or destruction of valuable parent donor material. The protocol, with further development, has the potential to underpin development of a transformation system for Primula, which would be of value in studies on flower development and disease resistance in laboratory grown plants

1,2,6-thiadiazinones as novel narrow spectrum calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) inhibitors

We demonstrate for the first time that 4H-1,2,6-thiadiazin-4-one (TDZ) can function as a chemotype for the design of ATP-competitive kinase inhibitors. Using insights from a co-crystal structure of a 3,5-bis(arylamino)-4H-1,2,6-thiadiazin-4-one bound to calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2), several analogues were identified with micromolar activity through targeted displacement of bound water molecules in the active site. Since the TDZ analogues showed reduced promiscuity compared to their 2,4-dianilinopyrimidine counter parts, they represent starting points for development of highly selective kinase inhibitors

An efficient direct solver for a class of mixed finite element problems

In this paper we present an efficient, accurate and parallelizable direct method for the solution of the (indefinite) linear algebraic systems that arise in the solution of fourth-order partial differential equations (PDEs) using mixed finite element approximations. The method is intended particularly for use when multiple right-hand sides occur, and when high accuracy is required in these solutions. The algorithm is described in some detail and its performance is illustrated through the numerical solution of a biharmonic eigenvalue problem where the smallest eigenpair is approximated using inverse iteration after discretization via the Ciarlet–Raviart mixed finite element method

Seed germination and in vitro regeneration of the African medicinal and pesticidal plant, Bobgunnia madagascariensis

Propagation of the medicinal and pesticidal tree, Bobgunnia madagascarensis is difficult due to poor and erratic germination of its seeds and slow growth of its seedlings. This study involved two separate experiments. The first evaluated the effect of pre-sowing treatments and growing medium on ex vitro seed germination and early seedling development. The second experiment involved in vitro germination, shoot initiation and rooting of shoots. Pre-sowing seed treatments involved soaking seeds in cold and hot water for 12 and 24 h and soaking in different concentrations (0, 100, 200, 400 and 800 mg/l) of gibberellic acid for 24 h. Soaking of seeds in cold or hot water for up to 24 h did not achieve more than 45% germination, while seeds treated with gibberellic acid achieved 76%) when seeds were sown in a growing medium without compost compared with a medium with compost (<43%). All shoot-tips isolated from the in vitro germinated seedlings on B5 media without plant growth regulators continued to grow as a single shoot, while shoot-tips cultured on B5 supplemented with 0.1 mg/l of naphthaleneacetic acid (NAA) and thidiazuron (TDZ) produced two shoots each after four weeks. It was concluded that B. madagascariensis seeds had very low ex vitro germination percentages. Although, in vitro cultures improved seed germination, axillary shoot multiplication and rooting were not satisfactory. Therefore, further studies are needed to develop an optimal in vitro multiplication protocol for B. madagascariensis

Efeitos da pulverização pré-colheita com thidiazuron sobre a qualidade e a maturação de frutos em macieiras

ABSTRACTApple trees, cultivars Gala and Fuji, were sprayed at full bloom with thidiazuron (TDZ) at the doses of 0, 5, 10, or 20 g (a.i.) ha-1 and fruit were assessed for quality and maturity. In both cultivars, the increase of TDZ dose had detrimental effects on fruit quality, causing a reduction of fruit red surface and an increase of percentage of fruit that was asymmetrical and with calyx-end rot. TDZ caused an increment of calyx-end aperture that might have increased calyx-end rot. TDZ increased density and the length : diameter (L : D) ratio of the fruit. The number of viable seeds was not affected by TDZ. TDZ resulted in a substantial delay of fruit maturity in ‘Gala’ but not in ‘Fuji’. TDZ also reduced soluble solids content (SSC) in ‘Gala’ and reduced titratable acidity in both cultivars. ______________________________________________________________________________ RESUMOMacieiras, cultivares Gala e Fuji, foram pulverizadas em plena floração com thidiazuron (TDZ), nas doses de 0; 5; 10 e 20 g (i.a.) ha-1, e os frutos avaliados em termos de qualidade e maturação. Em ambas as cultivares, o TDZ apresentou efeitos negativos na qualidade dos frutos, com redução na percentagem de cor vermelha na casca e aumento na percentagem de frutos assimétricos e com podridão carpelar. O TDZ causou aumento na abertura carpelar, o que pode ter ocasionado aumento de incidência de podridão carpelar. O TDZ aumentou a densidade e a relação comprimento : diâmetro (C : D) dos frutos. O número de sementes viáveis não foi afetado pelo TDZ. O TDZ retardou substancialmente a maturação dos frutos na cultivar Gala, mas não na cultivar Fuji. O TDZ reduziu os teores de sólidos solúveis totais na cultivar Gala e reduziu a acidez titulável em ambas as cultivares