To develop a model plant system for efficient functional analysis of mutagenized phytochrome polypeptides, we have overexpressed oat phytochrome A in Arabidopsis thaliana. R1 seedlings from selfed primary transformants segregated for hypocotyl length, when grown in the light, with a ratio of 3 short to 1 of normal length. When homozygous lines were established from these two size classes, accum...

Plant size is largely determined by the size of individual cells. A number of studies showed a link between ploidy and cell size in land plants, but this link remains controversial. In this study, post-germination growth, which occurs entirely by cell elongation, was examined in diploid and autotetraploid hypocotyls of Arabidopsis thaliana (L.) Heynh. Final hypocotyl length was longer in tetrap...

Shade avoidance is an ecologically and molecularly well-understood set of plant developmental responses that occur when the ratio of red to far-red light (R:FR) is reduced as a result of foliar shade. Here, a genome-wide association study (GWAS) in Arabidopsis thaliana was used to identify variants underlying one of these responses: increased hypocotyl elongation. Four hypocotyl phenotypes were...

Some of the most striking features of Rhizophoraceae mangrove saplings are their voluminous cylinder-shaped hypocotyls and thickened leaves. The hypocotyls are known to serve as floats during seed dispersal (hydrochory) and store nutrients that allow the seedling to root and settle. In this study we investigate to what degree the hypocotyls and leaves can serve as water reservoirs once seedling...

The effects of irradiating blue, UV-A, UV-B and a combination of the lights on anthocyanin accumulation at different hypocotyl positions were investigated in seedlings of the purple top turnip 'Tsuda'. The location of anthocyanin accumulation varied depending on different light spectra. Stronger accumulation of anthocyanin was induced (i) at the upper hypocotyl positions by blue light; (ii) mai...

The regulation of protein turnover by the ubiquitin proteasome system (UPS) is a major posttranslational mechanism in eukaryotes. One of the key components of the UPS, the COP9 signalosome (CSN), regulates 'cullin-ring' E3 ubiquitin ligases. In plants, CSN participates in diverse cellular and developmental processes, ranging from light signaling to cell cycle control. In this work, we isolated ...

Cannabis sativa L. is an annual herbaceous crop grown for the production of long extraxylary fibers, the bast fibers, rich in cellulose and used both in the textile and biocomposite sectors. Despite being herbaceous, hemp undergoes secondary growth and this is well exemplified by the hypocotyl. The hypocotyl was already shown to be a suitable model to study secondary growth in other herbaceous ...

The disulfated peptide growth factor phytosulfokine-α (PSK-α) is perceived by LRR receptor kinases. In this study, a role for PSK signaling through PSK receptor PSKR1 in Arabidopsis thaliana hypocotyl cell elongation is established. Hypocotyls of etiolated pskr1-2 and pskr1-3 seedlings, but not of pskr2-1 seedlings were shorter than wt due to reduced cell elongation. Treatment with PSK-α did no...

Ultraviolet (UV) radiation is an important constituent of sunlight that determines plant morphology and growth. It induces photomorphogenic responses but also causes damage to DNA. Arabidopsis mutants of the endonucleases that function in nucleotide excision repair, xpf-3 and uvr1-1, showed hypersensitivity to UV-B (280-320nm) in terms of inhibition of hypocotyl growth. SOG1 is a transcription ...

Blue light-induced regulation of cell elongation is a component of the signal response pathway for both phototropic curvature and inhibition of stem elongation in higher plants. To determine if blue light regulates cell elongation in these responses through shared or discrete pathways, phototropism and hypocotyl elongation were investigated in several blue light response mutants in Arabidopsis...