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Publications - Cell and Metabolic Biology
Publications
A T-DNA insertion mutant of FUSCA3 (fus3-T) in Arabidopsis thaliana exhibits several of the expected deleterious effects on seed development, but not the formation of brown seeds, a colouration which results from the accumulation of large amounts of anthocyanin. A detailed phenotypic comparison between fus3-T and a known splice point mutant (fus3-3) revealed that the seeds from both mutants do not enter dormancy and can be rescued at an immature stage. Without rescue, mature fus3-3 seeds are non-viable, whereas those of fus3-T suffer only a slight loss in their germinability. A series of comparisons between the two mutants uncovered differences with respect to conditional lethality, in histological and sub-cellular features, and in the relative amounts of various storage compounds and metabolites present, leading to a further dissection of developmental processes in seeds and a partial reinterpretation of the complex seed phenotype. FUS3 function is now known to be restricted to the acquisition of embryo-dependent seed dormancy, the determination of cotyledonary cell identity, and the synthesis and accumulation of storage compounds. Based on DNA binding studies, a model is presented which can explain the differences between the mutant alleles. The fus3-T lesion is responsible for loss of function only, while the fus3-3 mutation induces various pleiotropic effects conditioned by a truncation gene product causing severe mis-differentiation.
Publications
Among the plant hormones jasmonic acid and related derivatives are known to mediate stress responses and several developmental processes. Biosynthesis, regulation, and metabolism of jasmonic acid in Arabidopsis thaliana are reviewed, including properties of mutants of jasmonate biosynthesis. The individual signalling properties of several jasmonates are described.
Publications
Transport processes between plant and fungal cells are key elements in arbuscular mycorrhiza (AM), where H+‐ATPases are considered to be involved in active uptake of nutrients from the symbiotic interface. Genes encoding H+‐ATPases were identified in the genome of Medicago truncatula and three cDNA fragments of the H+‐ATPase gene family (Mtha 1 ‐ 3) were obtained by RT‐PCR using RNA from M. truncatula mycorrhizal roots as template. While Mtha 2 and Mtha 3 appeared to be constitutively expressed in roots and unaffected by AM development, transcripts of Mtha 1 could only be detected in AM tissues and not in controls. Further analyses by RT‐PCR revealed that Mtha 1 transcripts are not detectable in shoots and phosphate availability did not affect RNA accumulation of the gene. Localization of transcripts by in situ hybridization on AM tissues showed that Mtha 1 RNA accumulates only in cells containing fungal arbuscules. This is the first report of arbuscule‐specific induced expression of a plant H+‐ATPase gene in mycorrhizal tissues.
Publications
Treatment of barley leaf segments with jasmonic acid methyl ester (JM) leads to the accumulation of a set of newly formed abundant proteins. Among them, the most abun dant protein exhibits a molecular mass of 23 kDa (JIP‐23). Here, data are presented on the occurrence and expression of the lIP‐23 genes in different cultivars of Hordeum vulgare . Southern blot analysis of 80 cultivars revealed the occurrence of 2 to 4 genes coding for JIP‐23 in all cultivars. By means of Northern blot and immunoblot analysis it is shown that some cultivars lack the ex pression of jip‐23 upon treatment of primary leaves with JM as well as upon stress performed by incubation with 1 M sorbitol solution. During germination, however, all tested cultivars ex hibited developmental expression of jip‐23 . The results are dis cussed in terms of possible functions of JIP‐23 in barley.
This page was last modified on 27 Jan 2025 .
