Abscisic acid facilitates phosphate acquisition through the transcription factor ABA INSENSITIVE5 in Arabidopsis

Abstract

Low phosphate (LP) in soil is a common nutrient stress that severely restricts agricultural production, but the role, if any, of the major stress phytohormone abscisic acid (ABA) in plant phosphate (Pi) starvation responses remains elusive. Here, we report that LP-induced ABA accumulation promotes Pi uptake in an ABA INSENSITIVE5 (ABI5)-dependent manner in Arabidopsis thaliana. LP significantly activated plant ABA biosynthesis, metabolism, and stress responses, suggesting a role of ABA in the plant response to Pi availability. LP-induced ABA accumulation and expression of two major high-affinity phosphate transporter genes PHOSPHATE TRANSPORTER1;1/1;4 (PHT1;1/1;4) were severely impaired in a mutant lacking BETA-GLUCOSIDASE1 (BG1), which converts conjugated ABA to active ABA, and the mutant had shorter roots and less Pi content than wild-type plants under LP conditions. Moreover, a mutant of ABI5, which encodes a central transcription factor in ABA signaling, also exhibited suppressed root elongation and had reduced Pi content under LP conditions. ABI5 facilitated Pi acquisition by activating the expression of PHT1;1 by directly binding to its promoter, while overexpression of PHT1;1 completely rescued its Pi content under LP conditions. Together, our findings illustrate a molecular mechanism by which ABA positively modulates phosphate acquisition through ABI5 in the Arabidopsis response to phosphate deficiency.

Transcriptome analysis of axillary buds in low phosphorus stress and functional analysis of TaWRKY74s in wheat

“…While low Pi treatment induced an increase in ABA in wild-type plants, aba2-1 mutants showed less extent of ABA increase while no ABA increase was observed in bg1-1 mutants. This means that the release of ABA from ABA glucose esters by BG1 plays an important role in the accumulation of ABA in plants induced by low Pi treatment [ 25 ]. PHT is a class of phosphorus transporters; PHR1 , the positive regulator of PHT, is a core player in plant Pi starvation responses [ 26 ].…”

Identification of genetic and environmental factors influencing aerial root traits that support biological nitrogen fixation in sorghum

“…Under low nitrate conditions in the soil, ABA indirectly regulates lateral root growth in Arabidopsis, where signal transduction is modulated by ABI5 ( Signora et al 2001 ). Furthermore, ABI5 regulates phosphate absorption through ABA signaling, making it plausible that its expression is upregulated under reduced fertilizer conditions ( Zhang et al 2022 ). Moreover, nitric oxide negatively regulates ABA signaling to promote root growth via the scavenging of reactive oxygen species (ROS) by the S -nitrosylation of AtABI5 and OsTRAB1 ( Albertos et al 2015 ; Xu et al 2018 ).…”

A fungal secondary metabolism gene cluster enables mutualist-pathogen transition in root endophyteColletotrichum tofieldiae

“…In Ct3 , ABA-BOT genes serve to accelerate early induction of host PSR-related genes (at 10 dpi) even under Pi sufficient conditions, likely through the host ABA core pathways. This may reflect a positive role for ABA in PSR under low Pi (Aleksza et al ., 2017; Zhang et al ., 2022). In contrast, beneficial Ct strains induce host PSR-related genes specifically under low Pi, at a later phase (24 dpi), coincident with the appearance of PGP effects.…”