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Summary In seed plants, 1‐aminocyclopropane‐1‐carboxylic acid (ACC) is the precursor of the plant hormone ethylene but also has ethylene‐independent signaling roles. Nonseed plants produce ACC but do not efficiently convert it to ethylene. InArabidopsis thaliana, ACC is transported by amino acid transporters, LYSINE HISTIDINE TRANSPORTER 1 (LHT1) and LHT2. In nonseed plants,LHThomologs have been uncharacterized.Here, we isolated an ACC‐insensitive mutant (Mpain) that is defective in ACC uptake in the liverwortMarchantia polymorpha. Mpaincontained a frameshift mutation (1 bp deletion) in the MpLHT1coding sequence, and was complemented by expression of a wild‐type MpLHT1transgene. Additionally, ACC insensitivity was re‐created in CRISPR/Cas9‐Mplht1knockout mutants. We found that MpLHT1 can also transportl‐hydroxyproline andl‐histidine.We examined the physiological functions of MpLHT1in vegetative growth and reproduction based on mutant phenotypes. Mpainand Mplht1plants were smaller and developed fewer gemmae cups compared to wild‐type plants. Mplht1mutants also had reduced fertility, and archegoniophores displayed early senescence.These findings reveal that MpLHT1 serves as an ACC and amino acid transporter inM. polymorphaand has diverse physiological functions. We propose that MpLHT1 contributes to homeostasis of ACC and other amino acids inM. polymorphagrowth and reproduction.
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The first intron and promoter of Arabidopsis DIACYLGLYCEROL ACYLTRANSFERASE 1 exert synergistic effects on pollen and embryo lipid accumulation
Summary Accumulation of triacylglycerols (TAGs) is crucial during various stages of plant development. InArabidopsis, two enzymes share overlapping functions to produce TAGs, namely acyl‐CoA:diacylglycerol acyltransferase 1 (DGAT1) and phospholipid:diacylglycerol acyltransferase 1 (PDAT1). Loss of function of both genes in adgat1‐1/pdat1‐2double mutant is gametophyte lethal. However, the key regulatory elements controlling tissue‐specific expression of either gene has not yet been identified.We transformed adgat1‐1/dgat1‐1//PDAT1/pdat1‐2parent with transgenic constructs containing theArabidopsis DGAT1promoter fused to theAtDGAT1open reading frame either with or without the first intron.Triple homozygous plants were obtained, however, in the absence of theDGAT1first intron anthers fail to fill with pollen, seed yield isc. 10% of wild‐type, seed oil content remains reduced (similar todgat1‐1/dgat1‐1), and non‐Mendelian segregation of thePDAT1/pdat1‐2locus occurs. Whereas plants expressing theAtDGAT1pro:AtDGAT1transgene containing the first intron mostly recover phenotypes to wild‐type.This study establishes that a combination of the promoter and first intron ofAtDGAT1provides the proper context for temporal and tissue‐specific expression ofAtDGAT1in pollen. Furthermore, we discuss possible mechanisms of intron mediated regulation and how regulatory elements can be used as genetic tools to functionally replace TAG biosynthetic enzymes inArabidopsis.
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- Award ID(s):
- 2242822
- PAR ID:
- 10574967
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 245
- Issue:
- 1
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 263-281
- Size(s):
- p. 263-281
- Sponsoring Org:
- National Science Foundation
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