CLONING AND EXPRESSION STUDIES ON 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE AND ETHYLENE RECEPTOR GENES IN PELARGONIUM

T.M. Mutui, H. Mibus, M. Serek
Ethylene biosynthesis is controlled by the enzyme 1-aminocyclopropane-1-carboxylic acid (ACC) synthase. Previous ACC synthase cloning studies revealed a multi-gene family. Degenerate primer pair was used to amplify three DNA fragments using genomic DNA from ‘Katinka’ leaves. Amplification of several ACC synthase genes with only one PCR reaction was possible due to different number and size of introns in homologue DNA fragments. Sequence analysis of 2 novel partial putative ACC synthase led to their characterization and designation as PzACS3 and PzACS4. The effects of various treatments on ACC synthase and ethylene receptor (ETR) genes during Pelargonium leaf senescence were studied. Gene-specific primers were constructed using already cloned ACC synthase genes in gene bank, synthesized and expression studies were done using semi-quantitative RT-PCR. ACC synthase genes (PzACS3 and PzACS4) transcripts were respectively expressed or undetectable in roots. PhETR1 transcripts were strongly expressed in roots and flower buds whereas PhETR2 was constitutively expressed. Tissue-specific gene expression patterns suggest they have different roles in ethylene biosynthesis and signaling. Transcripts of PzACS3, PzACS4 and PhETR1 genes were expressed in a treatment-specific fashion. Ethylene effect was not apparent on expression of all investigated genes whereas ABA and dark storage respectively increased abundance of pGAC-1 and GACS2 transcripts in ‘Katinka’. Conversely, dark storage had no effect on GACS2 transcripts in ‘Ganymed’. This was due to either stress-induced ethylene that occurs after dark storage or ABA treatment. Thidiazuron (TDZ) strongly induced expression of the negative acting ethylene receptor, PhETR1. This could have reduced sensitivity of Pelargonium leaves to ethylene with beneficial effect of delaying the onset of leaf senescence.
Mutui, T.M., Mibus, H. and Serek, M. (2012). CLONING AND EXPRESSION STUDIES ON 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE AND ETHYLENE RECEPTOR GENES IN PELARGONIUM. Acta Hortic. 937, 703-710
DOI: 10.17660/ActaHortic.2012.937.85
https://doi.org/10.17660/ActaHortic.2012.937.85
1-aminocyclopropane-1-carboxylic acid (ACC) synthase, ethylene receptor (ETR1) genes, gene expression, Pelargonium × hortorum
English

Acta Horticulturae