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CRISPR/Cas systems enable gene editing through the induction of site‐specific DNA double‐strand breaks (DSB). However, the nature of the induced modification highly depends on the mechanism used for DNA DSB repair. Non‐homologous end joining (NHEJ)‐mediated targeted mutagenesis induced by CRISPR/Cas is an already standardly applied tool, which can lead to various different kinds of mutations at a specific genomic site. Nevertheless, precise genome modification using homologous donor sequences is still challenging in plants. Applications depending on the less frequent homologous recombination (HR) require further improvements to create an attractive and efficient tool for general application in plants. Focusing on this issue, we developed the in planta gene targeting (ipGT) system, which is based on the simultaneous excision of a stably integrated, homologous donor sequence and the induction of a DSB within the target site. In recent years, several improvements were achieved enhancing gene targeting (GT) frequencies. After the successful application of Streptococcus pyogenes Cas9 (SpCas9) and Staphylococcus aureus Cas9 (SaCas9) for ipGT, we were able to further improve the system using Lachnospiraceae bacterium Cas12a (LbCas12a), which also enables cleavage in T‐rich regions. Most recently, we tested an improved, temperature‐tolerant version of LbCas12a (ttLbCas12a) for ipGT and were able to further increase GT efficiencies. Here, we describe the experimental procedure of the recently published ipGT system using ttLbCas12a in Arabidopsis thaliana in detail. © 2020 The Authors. Basic Protocol 1: Construction of CRISPR/ttLbCas12a expression vector to analyze ipGT efficiencies Basic Protocol 2: Achieving heritable GT plants

We introduce the novel concepts of local and union book embeddings, and, as the corresponding graph parameters, the local page number pn (G) and the union page number pn u (G). Both parameters are relaxations of the classical page number pn(G), and for every graph G we have pn (G) pn u (G) pn(G). While for pn(G) one minimizes the total number of pages in a book embedding of G, for pn (G) we instead minimize the number of pages incident to any one vertex, and for pn u (G) we instead minimize the size of a partition of G with each part being a vertex-disjoint union of crossing-free subgraphs. While pn (G) and pn u (G) are always within a multiplicative factor of 4, there is no bound on the classical page number pn(G) in terms of pn (G) or pn u (G). We show that local and union page numbers are closer related to the graph's density, while for the classical page number the graph's global structure can play a much more decisive role. We introduce tools to investigate local and union book embeddings in exemplary considerations of the class of all planar graphs and the class of graphs of tree-width k.As an incentive to pursue research in this new direction, we offer a list of intriguing open problems.