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Intron-retained radish (Raphanus sativus L.) RsMYB1 transcripts found in colored-taproot lines enhance anthocyanin accumulation in transgenic Arabidopsis plants
Key message Overexpression of the naturally occurring intron-retained (IR) forms of radish RsMYB1 and RsTT8 transcripts in Arabidopsis causes a substantial increase in anthocyanin accumulation. The production of anthocyanins in plants is tightly controlled by the MYB–bHLH–WD40 (MBW) complex. In this...
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Published in: | Plant cell reports 2021-09, Vol.40 (9), p.1735-1749 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Key message
Overexpression of the naturally occurring intron-retained (IR) forms of radish
RsMYB1
and
RsTT8
transcripts in Arabidopsis causes a substantial increase in anthocyanin accumulation.
The production of anthocyanins in plants is tightly controlled by the MYB–bHLH–WD40 (MBW) complex. In this study, analysis of four radish (
Raphanus sativus
L.) inbred lines with different colored taproots revealed that regulatory genes of anthocyanin biosynthesis,
RsMYB1
and
RsTT8
, produce three transcripts, one completely spliced and two intron retention (IR1 and IR2) forms. Transcripts
RsMYB1-IR1
and
RsMYB1-IR2
retained the 1st (380 nt) and 2nd (149 nt) introns, respectively;
RsTT8-IR1
retained the 4th intron (113 nt);
RsTT8-IR2
retained both the 3rd (128 nt) and 4th introns. Levels of most IR forms were substantially low in radish samples, but the
RsTT8-IR2
level was higher than
RsTT8
in red skin/red flesh (RsRf) root. Since all IR forms contained a stop codon within the intron, they were predicted to encode truncated proteins with defective interaction domains, resulting in the inability to form the MBW complex in vivo. However, tobacco leaves transiently co-expressing
RsMYB1-IR
s and
RsTT8-IR
s showed substantially higher anthocyanin accumulation than those co-expressing their spliced forms. Consistently, co-expression of constructs encoding truncated proteins with spliced or IR forms of their interaction partner in tobacco leaves did not result in anthocyanin accumulation. Compared with
RsMYB1
, the overexpression of
RsMYB1-IR
s in Arabidopsis
pap1
mutant increased anthocyanin accumulation by > sevenfold and upregulated the expression of Arabidopsis flavonoid biosynthesis genes including
AtTT8
. Our results suggest that the stable co-expression of
RsMYB1-IR
s in fruit trees and vegetable crops could be used to increase their anthocyanin contents. |
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ISSN: | 0721-7714 1432-203X |
DOI: | 10.1007/s00299-021-02735-z |