Abstract
Phosphate (Pi) is a macronutrient that is essential for plant growth and development. However, the low mobility of Pi impedes uptake, thus reducing availability. Accordingly, plants have developed physiological strategies to cope with low Pi availability. Here, we report that the characteristic Arabidopsis thaliana Pi starvation responses are in part dependent on the activity of the nuclear growth-repressing DELLA proteins (DELLAs), core components of the gibberellin (GA)-signaling pathway. We first show that multiple shoot and root Pi starvation responses can be repressed by exogenous GA or by mutations conferring a substantial reduction in DELLA function. In contrast, mutants having enhanced DELLA function exhibit enhanced Pi starvation responses. We also show that Pi deficiency promotes the accumulation of a green fluorescent protein-tagged DELLA (GFP-RGA [repressor of ga1-3]) in root cell nuclei. In further experiments, we show that Pi starvation causes a decrease in the level of bioactive GA and associated changes in the levels of gene transcripts encoding enzymes of GA metabolism. Finally, we show that the GA-DELLA system regulates the increased root hair length that is characteristic of Pi starvation. In conclusion, our results indicate that DELLA-mediated signaling contributes to the anthocyanin accumulation and root architecture changes characteristic of Pi starvation responses, but do not regulate Pi starvation-induced changes in Pi uptake efficiency or the accumulation of selected Pi starvation-responsive gene transcripts. Pi starvation causes a reduction in bioactive GA level, which, in turn, causes DELLA accumulation, thus modulating several adaptively significant plant Pi starvation responses.
Highlights
Phosphate (Pi) is a macronutrient that is essential for plant growth and development
It has recently become apparent that the GA-DELLA proteins (DELLAs) mechanism plays an important role in modulating plant growth via integration of both environmental and endogenous signals (Lee at al., 2002; Fu and Harberd, 2003; Alvey and Harberd, 2005; Achard et al, 2006, 2007a, 2007 b; Penfield et al, 2006)
The work described in this article shows that the plant growth and developmental effects of nutrient limitation, in particular of Pi starvation, are mediated via the GA-DELLA mechanism
Summary
Phosphate (Pi) is a macronutrient that is essential for plant growth and development. To sustain growth in such limiting conditions, plants have evolved a number of developmental and metabolic responses to adapt both the internal Pi status in planta and the external soil Pi availability. These responses include changes in root morphology and architecture, accumulation of anthocyanin, and increases in the synthesis and secretion of. Gibberellin Signaling and Phosphate Starvation Responses are grown in LP conditions, exogenous auxin treatment dramatically inhibits the growth of primary roots and induces the formation of lateral roots. Analysis of the root architecture of ethylenesignaling mutants, such as etr, ctr, ein, ein, and hls, and of plants treated with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid show that ethylene does not promote the formation of lateral roots when Pi is limiting (Lopez-Bucio et al, 2002)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
