ArabidopsisMATE45 antagonizes local abscisic acid signaling to mediate development and abiotic stress responses

Abstract

Anthocyanins provide ideal visual markers for the identification of mutations that disrupt molecular responses to abiotic stress. We screened Arabidopsis mutants of ABC (ATP‐Binding Cassette) and MATE (Multidrug And Toxic compound Extrusion) transporter genes under nutritional stress and identified four genes (ABCG25, ABCG9, ABCG5, and MATE45) required for normal anthocyanin pigmentation. ABCG25 was previously demonstrated to encode a vascular‐localized cellular exporter of abscisic acid (ABA). Our results show that MATE45 encodes an aerial meristem‐ and a vascular‐localized transporter associated with the trans‐Golgi, and that it plays an important role in controlling the levels and distribution of ABA in growing aerial meristems and non‐meristematic tissues. MATE45 promoter‐GUS reporter fusions revealed the activity localized to the leaf and influorescence meristems and the vasculature. Loss‐of‐function mate45 mutants exhibited accelerated rates of aerial organ initiation suggesting at least partial functional conservation with the maize ortholog bige1. The aba2‐1 mutant, which is deficient in ABA biosynthesis, exhibited a number of phenotypes that were rescued in the mate45‐1 aba2‐1 double mutant. mate45 exhibited enhanced the seed dormancy, and germination was hypersensitive to ABA. Enhanced frequency of leaf primordia growth in mate45 seedlings grown in nutrient imbalance stress was ABA‐dependent. The ABA signaling reporter construct pRD29B::GUS revealed elevated levels of ABA signaling in the true leaf primordia of mate45 seedlings grown under nutritional stress, and gradually reduced signaling in surrounding cotyledon and hypocotyl tissues concomitant with reduced expressions of ABCG25. Our results suggest a role of MATE45 in reducing meristematic ABA and in maintaining ABA distribution in adjacent non‐meristematic tissues.

Drought Stress Responses and Resistance in Plants: From Cellular Responses to Long-Distance Intercellular Communication

“…Slight but significant ABA uptake activity of AtMATE45 was detected in E. coli cells expressing AtMATE45. These results suggest that AtMATE45 may antagonize meristematic ABA signaling, although it is unlikely to function as a bona fide ABA transporter (Kovinich et al, 2018).…”

“…Anthocyanin pigmentation related to ABA levels and ABA signaling has been demonstrated (Adams et al, 1999). Related to another ABA transporter described above in the ABC family, AtABCG25 was also included among four transporter genes found by genetic screening in AICs (Kovinich et al, 2018). AtMATE45 is mostly expressed at growing meristem sites and in the vasculature in Arabidopsis.…”

“…In the Arabidopsis MATE transporter family, AtMATE45 has been reported as a candidate ABA transporter (Kovinich et al, 2018). AtMATE45 was first identified as one of four transporter genes found by genetic screening to observe anthocyanin pigmentation under anthocyanin induction conditions (AICs).…”

Insights into long non-coding RNA regulation of anthocyanin carrot root pigmentation

“…Most of the known genes of the pathway and their main regulators were differentially expressed between the two genotypes (Supplementary Table S5 ). Several genes were induced in purple tissues and they mainly comprised genes representing: (1) the early step in the flavonoid/anthocyanin pathway, like chalcone synthase ( DcCHS1 /DCAR_030786); chalcone isomerase ( DcCHI1 /DCAR_027694) and ( DcCHIL /DCAR_019805); flavanone 3-hydroxylase ( DcF3H1 /DCAR_009483), and flavonoid 3′-hydroxylase ( DcF3′H1 /DCAR_014032); (2) cytochrome P450 (CYP450) proteins, putatively related to the flavonoid and isoflavonoid biosynthesis pathways 23 , 46 ; (3) ATP-binding cassette (ABC) transporters, potentially related to anthocyanin transport 47 , 48 ; and (4) genes from the late steps of the pathway, like dihydro-flavonol 4-reductase ( DcDFR1 /DCAR_021485), leucoanthocyanidin dioxygenase ( DcLDOX1 /DCAR_006772), and UDP-glycosyltransferase ( DcUFGT /DCAR_009823) and the recently described DcUCGXT1 /DCAR_021269 and DcSAT1 /MSTRG.8365, which were confirmed to be responsible for anthocyanin glycosylation and acylation, respectively 26 , 49 . Finally, the most significant regulatory genes of the pathway, belonging to the MYB, bHLH and WD40 TF gene families 21 , 23 – 26 were also differentially expressed between purple and orange genotypes (Supplementary Table S5 ).…”

Insights into long non-coding RNA regulation of anthocyanin carrot root pigmentation

“…Most of the known genes of the pathway and their main regulators were differentially expressed between the two genotypes ( Supplementary Table S5). Several genes were induced in purple tissues and they mainly comprised genes representing: i) the early proteins, putatively related to the flavonoid and isoflavonoid biosynthesis pathways 23,46 ; iii) ATP-binding cassette (ABC) transporters, potentially related to anthocyanin transport 47,48 ; and iv) genes from the late steps of the pathway, like dihydro-flavonol 4-reductase (DcDFR1/DCAR_021485), leucoanthocyanidin dioxygenase (DcLDOX1/ DCAR_006772), and UDP-glycosyltransferase (DcUFGT/DCAR_009823) and the recently described DcUCGXT1/DCAR_021269 and DcSAT1/MSTRG.8365, which were confirmed to be responsible for anthocyanin glycosylation and acylation, respectively 26,49 . Finally, the most significant regulatory genes of the pathway, belonging to the MYB, bHLH and WD40 TF gene families 21,[23][24][25][26] were also differentially expressed between purple and orange genotypes ( Supplementary Table S5).…”