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Reverse breeding: a novel breeding approach based on engineered meiosis
Erik Wijnker,Kees van Dun,C. Bastiaan de Snoo,Cilia L.C. Lelivelt,Joost J.B. Keurentjes,Nazatul Shima Naharudin,Maruthachalam Ravi,Simon Chan,Hans de Jong 한국육종학회 2012 한국육종학회 심포지엄 Vol.2012 No.07
Reverse breeding is a new plant breeding strategy based on crossover suppression during meiosis. This brings forth unprecedented possibilities like the almost instantaneous generation of homozygous parents for a chosen heterozygote. As a proof of concept, an Arabidopsis (Columbia-Landsberg) heterozygote was created that carried a RNAi:DMC1 construct stopping crossover formation. Gametes of this heterozygote were grown directly into doubled haploid offspring. These offspring show different combinations of (non-recombinant) Columbia and Landsberg chromosomes. Among these doubled haploids we retrieved the original Columbia parent and a complete set of chromosome substitution lines. From among these we could easily select two so called “complementing DHs” from which the Col-Ler hybrid could be re-created. Essentially, breeders can now bring single choice uncharacterized heterozygotes into a hybrid breeding program by creating parental lines for them. Reverse breeding superficially resembles apomixis (clonal reproduction through seeds) since both allow the preservation of heterozygous genotypes. Reverse breeding, however, has very different uses because it generates homozygous breeding lines. It thus allows for the improvement of the starting heterozygote because new traits can be introgressed into its newly produced parental lines. Reverse breeding is thought to be suitable for crops with smaller chromosome numbers (x ≤ 12). It will be discussed how reverse breeding could be developed for such crops, and it will be shown how reverse breeding presents very interesting new possibilities studying epistasis and heterosis through chromosome substitution lines. Further experiments with reverse breeding lines allow testing of a variety of intriguing breeding questions like to what extent a (heterozygous) genome actually determines a plants phenotype.
Kim, Seok-Jin,Mahmood, Javeed,Kim, Changmin,Han, Gao-Feng,Kim, Seong-Wook,Jung, Sun-Min,Zhu, Guomin,De Yoreo, James J.,Kim, Guntae,Baek, Jong-Beom American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.5
<P>Because they provide lower cost but comparable activity to precious platinum (Pt)-based catalysts, nonprecious iron (Fe)-based materials, such as Fe/Fe<SUB>3</SUB>C and Fe–N–C, have gained considerable attention as electrocatalysts for the oxygen reduction reaction (ORR). However, their practical application is hindered by their poor stability, which is attributed to the defective protection of extremely unstable Fe nanoparticles. Here, we introduce a synthesis strategy for a stable Fe-based electrocatalyst, which was realized by defect-free encapsulation of Fe nanoparticles using a two-dimensional (2D) phenazine-based fused aromatic porous organic network (Aza-PON). The resulting Fe@Aza-PON catalyst showed electrocatalytic activity (half-wave potential, 0.839 V; Tafel slope, 60 mV decade<SUP>–1</SUP>) comparable to commercial Pt on activated carbon (Pt/C, 0.826 V and 90 mV decade<SUP>–1</SUP>). More importantly, the Fe@Aza-PON displayed outstanding stability (zero current loss even after 100 000 cycles) and tolerance against contamination (methanol and CO poisoning). In a hybrid Li–air battery test, the Fe@Aza-PON demonstrated performance superior to Pt/C.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2018/jacsat.2018.140.issue-5/jacs.7b10663/production/images/medium/ja-2017-10663c_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja7b10663'>ACS Electronic Supporting Info</A></P>