Fluorine containing topolin cytokinins for Phalaenopsis amabilis (L.) Blume micropropagation

In vitro cloning of Phalaenopsis hybrids is generally characterized by slow growth and low multiplication rates. Therefore, the impact of 6-(3-fluorobenzylamino)purine (FmT) and its 9-beta-D-riboside (FmTR) was evaluated. These halogenated compounds have been selected based on their very high cytokinin activity in previous bioassays. The Phalaenopsis plantlets formed significantly more, but smaller new shoots when treated with FmTR (25.3) compared to FmT (14.6) and BA (7.0). Furthermore, FmTR treatment completely abolished rooting during the micropropagation phase. Additionally, an interaction between cytokinin type and headspace aeration was noticed. For all treatments, the number of shoots increased significantly when grown in tightly closed containers. The use of fluorinated topolins might present a breakthrough in the in vitro micropropagation of Phalaenopsis

Drosophilid flies (Diptera: Drosophilidae) of Georgia (Sakartvelo) with new records for the country

Four genera and 12 species of drosophilid flies have been recorded during our survey in five regions of Georgia in 2021. Two genera, Amiota (Loew, 1862) and Gitona Meigen, 1830, and four species (Amiota subtusradiata Duda 1934, Drosophila busckii Coquillett 1901, D. kuntzei Duda, 1924, and Gitona distigma Meigen, 1830) represent new records for the fauna of Georgia (Sakartvelo)

Cytokinin oxidase/dehydrogenase inhibitors stimulate 2iP to induce direct somatic embryogenesis in Coffea arabica

Somatic embryogenesis in Coffea spp. is important for mass production and genetic engineering. Coffee is an exceptional case, as somatic embryogenesis can be induced by applying a cytokinin such as 2iP as the only plant growth regulator. 1-(2-(2-Hydroxyethyl)phenyl)-3-(3-(trifluoromethoxy)phenyl)urea (3TFM-2HE) and 1-(3-bromo-5-(trifluoromethoxy)phenyl)-3-(2-(2-hydroxyethyl)phenyl)urea (3TFM,5Br-2HE) are two newly designed cytokinin oxidase/dehydrogenase inhibitors (CKX) from the diphenylurea group. We used a Coffea arabica leaf disks bioassay to demonstrate the indirect somatic embryo induction potential of these compounds. The leaf disks were incubated on modified Murashige and Skoog (MS) semi-solid medium in which 3TFM-2HE or 3TFM,5Br-2HE were combined with N-6-(2-isopentenyl)adenine (2iP). Although these compounds do not possess intrinsic cytokinin activity, they enhanced the activity of 2iP, resulting in direct somatic embryogenesis after seven weeks. The best results were obtained with 1 mu M 3TFM-2HE and 5 or 10 mu M 2iP. Maturation of somatic embryos into fully developed plants took place on medium supplemented with 0.5 mu M kinetin and the somatic embryos developed true leaves and a root system

A calmodulin antagonist protects in vitro raspberries against disturbed photosynthesis caused by constant light and cytokinin

Leaf chlorosis is often a problem in micropropagated Rubus idaeus, which makes successful acclimatization difficult. We found that leaf bleaching becomes extreme when in vitro plants are exposed to continuous fluorescent light in the presence of 6-benzyl adenine (BA) or isopentenyl adenine (2iP). These cytokinins had a profound negative effect on the photosynthetic apparatus measured by the chlorophyll index (ChlIdx), photosystem II efficiency (Fv/Fm) and anthocyanin reflection index (AriIdx). Since calmodulin plays a role in the regulation of photosynthesis, we investigated the impact of calmodulin antagonist Chlorpromazine hydrochloride (CPZ) on this harmful bleaching effect. In cytokinin plus CPZ treated plants, ChlIdx was three times greater and Fv/Fm was increased 50% than in only cytokinins treated plants. while plants in hormone-free control medium had the highest ChlIdx and Fv/Fm. This study illustrates how drugs for humans, like the antipsychotic medication CPZ, can also be useful in other biological systems, such as in this case, where CPZ contributes to the quality of in vitro plants. Key Message: Calmodulin antagonist chlorpromazine hydrochloride can prevent leaf chlorosis in micropropagated raspberry culture, and can be used to optimize commercial raspberry micropropagation and contribute to delivery healthy in vitro plants

Belgian endive-derived biostimulants promote shoot and root growth in vitro

Recovering biostimulant compounds from by-products of crops is a promising strategy to add value, enhance sustainability, and increase the environmental safety of the agricultural production chain. Here, we report consistent root and shoot growth-stimulating bioactivity present in water-based extracts from Belgian endive forced roots (Cichorium intybus var. foliosum) over two consecutive harvest years. The shoot and the primary root of in vitro cultivated Arabidopsis thaliana treated with Belgian endive extract were about 30% increased in size compared to plants grown under control conditions. The ornamental species Plectranthus esculentus also showed enhanced in vitro shoot and root growth, suggesting bioactivity on a broad range of species. Fractionation of the Belgian endive extracts into aqueous and organic subfractions coupled with bioactivity measurements showed that the principal root and shoot growth-promoting ingredients are primarily water-soluble. NMR-based characterization of the bioactive aqueous fractions revealed the presence of predominantly sugars and organic acids. Malate and sugars were abundant and common to all water fractions, suggesting these molecules contributed to the growth stimulation phenotype. The findings indicate that Belgian endive roots are a source for the development of organic waste-derived biostimulants with potential for application in tissue culture and putatively for soil-grown crop production

Diphenylurea-derived cytokinin oxidase/dehydrogenase inhibitors for biotechnology and agriculture

International audienceIncreasing crop productivity is our major challenge if we are to meet global needs for food, fodder and fuel. Controlling the content of the plant hormone cytokinin is a method of improving plant productivity. Cytokinin oxidase/dehydrogenase (CKO/CKX) is a major target in this regard because it degrades cytokinins. Here, we describe the synthesis and biological activities of new CKX inhibitors derived mainly from diphenylurea. They were tested on four CKX isoforms from maize and Arabidopsis, where the best compounds showed IC50 values in the 10-8 M concentration range. The binding mode of the most efficient inhibitors was characterized from high-resolution crystal complexed structures. Although these compounds do not possess intrinsic cytokinin activity, we have demonstrated their tremendous potential for use in the plant tissue culture industry as well as in agriculture. We have identified a key substance, compound 19, which not only increases stress resistance and seed yield in Arabidopsis, but also improves the yield of wheat, barley and rapeseed grains under field conditions. Our findings reveal that modulation of cytokinin levels via CKX inhibition can positively affect plant growth, development and yield, and prove that CKX inhibitors can be an attractive target in plant biotechnology and agriculture

Diphenylurea-derived cytokinin oxidase/dehydrogenase inhibitors for biotechnology and agriculture

International audienceIncreasing crop productivity is our major challenge if we are to meet global needs for food, feed and fuel. Controlling the level of the plant hormones cytokinins is a mean of improving plant productivity. Cytokinin oxidase/dehydrogenase (CKO/CKX) is a major target in this regard because it degrades cytokinins. Here, we describe the synthesis and biological activities of new CKX inhibitors derived mainly from diphenylurea. They were tested on four CKX isoforms from maize and Arabidopsis, where the best compounds showed IC50 values in the 10 -8 M concentration range. The binding mode of the most efficient inhibitors was characterized from high-resolution crystal complexed structures. Although these compounds do not possess intrinsic cytokinin activity, we have demonstrated their tremendous potential for use in the plant tissue culture industry as well as in agriculture. We have identified a key substance, compound 19, which increases stress resistance and seed yield in Arabidopsis, but also improves the yield of wheat, barley and rapeseed grains under field conditions. Thus our findings reveal that subtle modulation of cytokinin levels via CKX inhibition can positively affect plant growth, development and yield, and underline the fact that CKX inhibitors truly deserve to attract interest in plant biotechnology and agriculture