Ectopic Overexpression of a Novel R2R3-MYB, NtMYB2 from Chinese Narcissus Represses Anthocyanin Biosynthesis in Tobacco.

Muhammad Anwar,Saquib Waheed,Andrew Allan,Guiqing Wang,Jiacheng Wu,Lihui Zeng

doi:10.3390/molecules23040781

Abstract

R2R3 MYB transcription factors play key functions in the regulation of secondary metabolites. In the present study, a R2R3 MYB transcriptional factor NtMYB2 was identified from Chinese narcissus (Narcissus tazetta L. var. Chinensis Roem) and functionally characterized. NtMYB2 belongs to subgroup 4 of the R2R3 MYB transcription factor family that are related to repressor MYBs involved in the regulation of anthocyanin and flavonoids. Transient expression confirmed that NtMYB2 strongly reduced the red pigmentation induced by MYB- anthocyanin activators in agro-infiltrated tobacco leaves. Ectopic expression of NtMYB2 in tobacco significantly reduced the pigmentation and altered the floral phenotypes in transgenic tobacco flowers. Gene expression analysis suggested that NtMYB2 repressed the transcript levels of structural genes involved in anthocyanin biosynthesis pathway, especially the UFGT gene. NtMYB2 gene is expressed in all examined narcissus tissues; the levels of transcription in petals and corona is higher than other tissues and the transcription level at the bud stage was highest. These results show that NtMYB2 is involved in the regulation of anthocyanin biosynthesis pathway and may act as a repressor by down regulating the transcripts of key enzyme genes in Chinese narcissus.

Highlights

Chinese narcissus (Narcissus tazetta L. var. chinensis Roem) is a perennial bulbous plant which belongs to the Amaryllidaceae family
The results suggest NtMYB2 may be a repressor of anthocyanin biosynthesis
The 30 end of NtMYB2 open reading frame (ORF) was isolated by 30 RACE-PCR with two gene specific primers GP1, GP2 (Table 1) and universal primer (UPM) and a 912 bp fragment was obtained

Summary

Introduction

Chinese narcissus (Narcissus tazetta L. var. chinensis Roem) is a perennial bulbous plant which belongs to the Amaryllidaceae family. Chinensis Roem) is a perennial bulbous plant which belongs to the Amaryllidaceae family. It has very popular attractive ornamental flowers with significant commercial and cultural value. It has been grown in China and East Asia from many years as a traditional and commercial flower. Narcissus has been reported as a triploid species, mostly propagated by a vegetative method, as genetically advanced improvement using traditional cross breeding is complicated [1]. Only a few cultivars have been used for commercial production in China and many agronomic characters have to be improved such as flower colors [2]. In Chinese narcissus, the flower colors are white and yellow.

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Discussion

Conclusion