Eliminating the purple acid phosphatase AtPAP26 in Arabidopsis thaliana delays leaf senescence and impairs phosphorus remobilization

Abstract

SummaryLimitation of crop productivity by suboptimal phosphorus (P) nutrition is a widespread concern. Enhanced crop P-use efficiency could be achieved by improving P remobilization from senescing leaves to developing tissues and seeds. Transcriptomic studies indicate that hundreds of Arabidopsis thaliana genes are up-regulated during leaf senescence, including that encoding the purple acid phosphatase (PAP) AtPAP26 (At5g34850).In this study, biochemical and functional genomic tools were integrated to test the hypothesis that AtPAP26 participates in P remobilization during leaf senescence.An eightfold increase in acid phosphatase activity of senescing leaves was correlated with the accumulation of AtPAP26 transcripts and immunoreactive AtPAP26 polypeptides. Senescing leaves of an atpap26 T-DNA insertion mutant displayed a > 90% decrease in acid phosphatase activity, markedly impaired P remobilization efficiency and delayed senescence. This was paralleled by reduced seed total P concentrations and germination rates.These results demonstrate that AtPAP26 loss of function causes dramatic effects that cannot be compensated for by any other PAP isozyme, even though Arabidopsis contains 29 different PAP genes. Our current and earlier studies establish that AtPAP26 not only helps to scavenge P from organic P sources when Arabidopsis is cultivated in inorganic orthophosphate (Pi)-deficient soils, but also has an important P remobilization function during leaf senescence.

The Difference of Physiological and Proteomic Changes in Maize Leaves Adaptation to Drought, Heat, and Combined Both Stresses

“…Purple acid phosphatase (PAP) family members were involved in extensive aspects of plant development, mineral homeostasis and stress responses (González-Muñoz et al, 2015). In Arabidopsis thaliana , the elimination of AtPAP26 disturbed phosphorus remobilization and delayed leaf senescence (Robinson et al, 2012). In the current study, heat stress and combined stress down-regulated PAP expression.…”

Improving phosphorus efficiency in cereal crops: Is breeding for reduced grain phosphorus concentration part of the solution?

“…A second line of enquiry using lpa mutants or transgenic plants with altered phosphatase scavenging capacity has also suggested that alterations to seed P affect seed germination and seedling vigor (Raboy, 2009; Robinson et al, 2012). Studies with lpa mutants across a range of species found reduced seedling vigor or impaired germination compared to wild-type parent lines (Meis et al, 2003; Kim and Tai, 2011).…”

Delayed degradation of chlorophylls and photosynthetic proteins in Arabidopsis autophagy mutants during stress-induced leaf yellowing

“…In the early phase of leaf senescence, developmental and environmental cues signal the plant cells to activate transcription factors (TFs) that modulate the expression of senescence-associated genes (SAGs) (Guo and Ecker, 2004; Balazadeh et al , 2008). The products of these SAGs conduct the highly ordered breakdown of intracellular organelles, including the degradation of proteins and macromolecules to remobilize leaf nutrients into other developing organs such as new leaves or seeds, or into storage organs (Lim et al , 2007; Robinson et al , 2012). …”