Colchicine application significantly affects plant performance in the second generation of synthetic polyploids and its effects vary between populations.

Background and Aims: Understanding the direct consequences of polyploidization is necessary for assessing the evolutionary significance of this mode of speciation. Previous studies have not studied the degree of between-population variation that occurs due to these effects. Although it is assumed that the effects of the substances that create synthetic polyploids disappear in second-generation synthetic polyploids, this has not been tested. Methods: The direct consequences of polyploidization were assessed and separated from the effects of subsequent evolution in Vicia cracca , a naturally occurring species with diploid and autotetraploid cytotypes. Synthetic tetraploids were created from diploids of four mixed-ploidy populations. Performance of natural diploids and tetraploids was compared with that of synthetic tetraploids. Diploid offspring of the synthetic tetraploid mothers were also included in the comparison. In this way, the effects of colchicine application in the maternal generation on offspring performance could be compared independently of the effects of polyploidization. Key Results: The sizes of seeds and stomata were primarily affected by cytotype, while plant performance differed between natural and synthetic polyploids. Most performance traits were also determined by colchicine application to the mothers, and most of these results were largely population specific. Conclusions: Because the consequences of colchicine application are still apparent in the second generation of the plants, at least the third-generation polyploids should be considered in future comparisons. The specificities of the colchicine-treated plants may also be caused by strong selection pressures during the creation of synthetic polyploids. This could be tested by comparing the initial sizes of plants that survived the colchicine treatments with those of plants that did not. High variation between populations also suggests that different polyploids follow different evolutionary trajectories, and this should be considered when studying the effects of polyploidization.

Design and synthesis of fused bicyclic inhibitors targeting the L5 loop site of centromere-associated protein E.

Centromere-associated protein-E (CENP-E) is a mitotic kinesin which plays roles in cell division, and is regarded as a promising therapeutic target for the next generation of anti-mitotic agents. We designed novel fused bicyclic CENP-E inhibitors starting from previous reported dihydrobenzofuran derivative (S)-(+)-1. Our design concept was to adjust the electron density distribution on the benzene ring of the dihydrobenzofuran moiety to increase the positive charge for targeting the negatively charged L5 loop of CENP-E, using predictions from electrostatic potential map (EPM) analysis. For the efficient synthesis of our 2,3-dihydro-1-benzothiophene 1,1-dioxide derivatives, a new synthetic method was developed. As a result, we discovered 6-cyano-7-trifluoromethyl-2,3-dihydro-1-benzothiophene 1,1-dioxide derivative (+)-5d (Compound A) as a potent CENP-E inhibitor with promising potential for in vivo activity. In this Letter, we discuss the design and synthetic strategy used in the discovery of (+)-5d and structure-activity relationships for its analogs possessing various fused bicyclic L5 binding moieties.

Colchicine-mediated in vitro polyploidization in gerbera hybrid.

An efficient in vitro protocol for high-frequency polyploidization for the first time in gerbera hybrid (BGC-2019-01) was developed in the present study. Two-week-old in vitro-developed shoots (tips) were treated individually with 0.1%, 0.25% and 0.5% (w/v) colchicine solutions for 4, 6, 8, and 12 h. The colchicine-treated shoot tips were then inoculated on Murashige and Skoog (MS) medium fortified with 1.5 mg/l meta-Topolin for multiple shoot proliferation and later transferred into 1.5 mg/l indole-3-acetic acid-fortified MS medium for rooting of shoots. The ploidy levels of the colchicine-treated and regenerated plantlets along with the non-treated ones were confirmed via flow cytometry analysis and metaphasic chromosome count. The highest frequency of tetraploid plantlets (50%) were obtained when shoot tips were treated with 0.1% colchicine for 4 h. Morphological observations revealed that induced tetraploid plantlets exhibited delayed fresh shoot initiation, fewer but longer shoots, as well as fewer but broader leaves. Likewise, the study of stomata revealed that in comparison to their diploid counterparts, the tetraploid plantlets exhibited less frequent yet significantly larger stomata, and higher number of chloroplasts. The tetraploids were recorded with significantly higher chlorophyll, carotenoid, and anthocyanin content during the photosynthetic pigment analyses. During ex vitro acclimatization and field growth, the tetraploid plants exhibited delayed proliferation but with higher vigor and thickened broad leaves. The genetic uniformity among the diploid and the tetraploid plants was confirmed using conserved DNA-derived polymorphism (CDDP), directed amplification of minisatellite-region DNA (DAMD), inter simple sequence repeats (ISSR), and start codon targeted (SCoT) polymorphism marker systems. The tetraploids developed in the present study would be of immense importance for the genetic improvement of gerbera as far as its ornamental values are concerned.