Transgenic expression of a putative calcium transporter affects the time of Arabidopsis flowering

Abstract

These authors contributed equally to this work. SummaryPPF1 is a gibberellin-induced, vegetative growth-specific gene, first isolated from short-day (SD)-grown G2 pea plants. In the current work, we found that transgenic Arabidopsis plants overexpressing the PPF1 gene (PPF1 (þ)) flowered much later and had a significantly longer lifespan compared to control plants, whereas suppression of this gene (PPF1 (-)) resulted in a very rapid reproductive cycle. Western blotting analyses of PPF1 (þ) and (-) plant lines revealed a positive correlation between the amount of antibody-reactive protein and the time of flowering. Green flourescent protein (GFP) co-expression assays showed that the PPF1 protein is likely localized in chloroplast membranes. Transgenic expression of PPF1 affected the calcium storage capacities since chloroplasts isolated from PPF1 (þ) plants contained high Ca 2þ levels while chloroplasts of PPF1 (-) plants contained very low amounts of calcium ion. Using Novikoff human hepatoma cells, we demonstrated that expression of PPF1 leads to a significant inward calcium ion current that was absent in untransformed cells. We conclude that, as a putative calcium ion carrier, PPF1 affects the flowering time of higher plants by modulating Ca 2þ storage capacity within chloroplasts.

Mutation ofArabidopsis BARD1Causes Meristem Defects by Failing to ConfineWUSCHELExpression to the Organizing Center

“…Three Arabidopsis mutant lines with disrupted BARD1 were obtained from SALK collections (ABRC; http://signal.salk.edu): bard1-1, SALK_097601; bard1-2, SALK_031862; and bard1-3, SALK_003498. Seeds were surface-sterilized with 0.1% HgCl 2 , germinated on Murashige and Skoog medium for 2 weeks, transferred to soil, and grown in fully automated growth chambers (Conviron) with a 16/8 h light/dark cycle at 238C in 70% humidity (Wang et al, 2003). The wus-1 mutant originated from Thomas Laux and was a gift from K. Chong.…”

CML24, Regulated in Expression by Diverse Stimuli, Encodes a Potential Ca2+ Sensor That Functions in Responses to Abscisic Acid, Daylength, and Ion Stress

“…Induction of expression by cold of EARLI1, a vernalization-and photoperiod-responsive Arabidopsis gene encoding a putative lipid transfer protein, is Ca 21 dependent (Wilkosz and Schlappi, 2000;Bubier and Schlappi, 2004). Furthermore, antisense Arabidopsis transgenics for a putative Ca 21 receptor and Arabidopsis transgenics overexpressing PPF1, which encodes a putative Ca 21 transporter in pea (Pisum sativum), are delayed in flowering (Han et al, 2003;Wang et al, 2003).…”

Regulation of the ALBINO3-mediated transition to flowering in Arabidopsis depends on the expression of CO and GA1

“…Transgenic Arabidopsis plants expressing the ALBINO3 gene were obtained as described by Wang et al (2003). The full-length ALBINO3 gene isolated from Arabidopsis (cv.…”

“…PPF1 was cloned from the G2 pea mutant in which vegetative apical buds grow continuously for a much longer duration on short days (SDs) than on LDs (Wang et al 2003, Li et al 2004. Recent studies suggest that PPF1 regulates flowering time in higher plants by encoding a putative calcium ion transporter to modulate the Ca 2+ storage capacity within chloroplasts (Wang et al 2003).…”

“…Recent studies suggest that PPF1 regulates flowering time in higher plants by encoding a putative calcium ion transporter to modulate the Ca 2+ storage capacity within chloroplasts (Wang et al 2003). Further, over-expression of PPF1 in transgenic Arabidopsis plants was observed to affect the chloroplast development; thus, the function of PPF1 is similar to that of ALBINO3 (Sundberg et al 1997, Xu et al 2002.…”