Jiang, Panpan (2017). Light signaling in Arabis alpina, a perennial relative of Arabidopsis thaliana. PhD thesis, Universität zu Köln.
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Abstract
Light is one of the most important environmental factors affecting plant development throughout the whole life cycle. Arabidopsis SPA and COP1 proteins act as central repressors of photomorphogenesis. However, previous studies on the functions of SPA and COP1 proteins are limited to only a few species and not in perennial species. In the present study, I examined the functionality of COP1 and SPA1 proteins from the new perennial model species Arabis alpina in Arabidopsis. The open reading frame of COP1 and SPA1 in the wild type A. alpina Paj were amplified and expressed in Arabidopsis cop1 and spa mutants, respectively. The analyses in the transgenic plants suggested conserved basic mechanisms of AaCOP1 and AaSPA1 during evolution between perennials and annuals in Brassicaceae family. The light regulation of SPA (SPA1/2/3/4) transcripts in A. alpina Paj was similar as in Arabidopsis. In the accession Wca, however, AaSPA2 mRNA abundance was increased by light, suggesting a different light regulation mechanism on Wca SPA2 in comparison to the wild type Paj. Natural variation in photoperiodic flowering has been studied in Arabidopsis, the loss- or gain-of- function of phytochromes (PHYA, PHYB, PHYC, PHYD) and cryptochromes (CRY2) could lead to reduced photoperiod responses in natural accessions of Arabidopsis. In the present study, natural variation of photoperiodic flowering in different A. alpina accessions was investigated. The accession Wca acts as a photoperiod-insensitive plant. A time course experiment was conducted to analyze the expression of the floral meristem identity genes AaLFY and AaAP1, which could support the observed photoperiod-insensitivity in Wca. Furthermore, Wca did not respond to different fluence rates of red light, suggesting a possibly dysfunctional phyB in Wca. On the other hand, the distinct flowering behavior between the long-day-plant Dor and the photoperiod- insensitive Wca could not be correlated to the diurnal oscillation of AaCO and AaFT. Moreover, the decrease of AaFT expression in the SD/LD shift experiment suggests additional factors might be involved in the floral transition in Wca. Arabidopsis responds to low R:FR ratio with elongated hypocotyl and petiole length at seedlings stage, and with the elongation of petiole in the rosette leaves, inhibition of leaf blade expansion and accelerated flowering in adult plants. The responses of A. alpina Paj to low R:FR appear to be age-dependent: as Paj displayed tolerance to shade in two-week-old seedlings but exhibited elongation of stem in eight-week-old adult plants. The expression of auxin biosynthesis genes YUCs in A. alpina could be correlated to the age-dependent SAS phenotype observed.
Item Type: | Thesis (PhD thesis) | ||||||||
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URN: | urn:nbn:de:hbz:38-76865 | ||||||||
Date: | 14 July 2017 | ||||||||
Language: | English | ||||||||
Faculty: | Faculty of Mathematics and Natural Sciences | ||||||||
Divisions: | Faculty of Mathematics and Natural Sciences > Department of Biology > Botanical Institute | ||||||||
Subjects: | Natural sciences and mathematics Agriculture |
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Date of oral exam: | 24 April 2017 | ||||||||
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Refereed: | Yes | ||||||||
URI: | http://kups.ub.uni-koeln.de/id/eprint/7686 |
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