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Publications - Cell and Metabolic Biology
Publications
Genetic resources for the model plant Arabidopsis comprise mutant lines defective in almost any single gene in reference accession Columbia. However, gene redundancy and/or close linkage often render it extremely laborious or even impossible to isolate a desired line lacking a specific function or set of genes from segregating populations. Therefore, we here evaluated strategies and efficiencies for the inactivation of multiple genes by Cas9-based nucleases and multiplexing. In first attempts, we succeeded in isolating a mutant line carrying a 70 kb deletion, which occurred at a frequency of ~ 1.6% in the T2 generation, through PCR-based screening of numerous individuals. However, we failed to isolate a line lacking Lhcb1 genes, which are present in five copies organized at two loci in the Arabidopsis genome. To improve efficiency of our Cas9-based nuclease system, regulatory sequences controlling Cas9 expression levels and timing were systematically compared. Indeed, use of DD45 and RPS5a promoters improved efficiency of our genome editing system by approximately 25–30-fold in comparison to the previous ubiquitin promoter. Using an optimized genome editing system with RPS5a promoter-driven Cas9, putatively quintuple mutant lines lacking detectable amounts of Lhcb1 protein represented approximately 30% of T1 transformants. These results show how improved genome editing systems facilitate the isolation of complex mutant alleles, previously considered impossible to generate, at high frequency even in a single (T1) generation.
Publications
In barley leaves a group of genes is expressed in response to treatment with jasmonates and abscisic acid (ABA) [21]. One of these genes coding for a jasmonate-induced protein of 23 kDa (JIP-23) was analyzed to find out the link between ABA and jasmonates by recording its expression upon modulating independently, the endogenous level of both of them. By use of inhibitors of JA synthesis and ABA degradation, and the ABA-deficient mutant Az34, as well as of cultivar-specific differences, it was shown that endogenous jasmonate increases are necessary and sufficient for expression of this gene. The endogenous rise of ABA did not induce synthesis of JIP-23, whereas exogenous ABA did not act via jasmonates. Different signalling pathways are suggested and discussed.
Publications
This article surveys the currently isolated and identified GA conjugates, their synthesis and evaluates modern methods for analysing GA glucose conjugates. The metabolism of applied GAs in higher plant systems leading, in most cases, to GA conjugates is also considered. The enzymology of the formation and hydrolysis of GA glucose conjugates is discussed in connection with their possible physiological function.
Publications
Data on the occurrence of free and conjugated gibberellins in different tribes of Gramineae are compiled and discussed with regard to their biosynthetic pathways. From the gibberellins detected so far the functioning of both the early 13-hydroxylation and the non-3,13-hydroxylation pathway of GA biosynthesis in gramineous plants can be deduced and the discovery of further gibberellin conjugates may be expected.
This page was last modified on 27 Jan 2025 .
