Functional Characterisation of Banana (Musa spp.) 2-Oxoglutarate-Dependent Dioxygenases Involved in Flavonoid Biosynthesis

Mareike Busche,Stefan Martens,Ralf Stracke,Christopher Acatay,Bernd Weisshaar

doi:10.3389/fpls.2021.701780

Mareike Busche, Stefan Martens + Show 3 more

Open Access

https://doi.org/10.3389/fpls.2021.701780

Copy DOI

Abstract

Bananas (Musa) are non-grass, monocotyledonous, perennial plants that are well known for their edible fruits. Their cultivation provides food security and employment opportunities in many countries. Banana fruits contain high levels of minerals and phytochemicals, including flavonoids, which are beneficial for human nutrition. To broaden the knowledge on flavonoid biosynthesis in this major crop plant, we aimed to identify and functionally characterise selected structural genes encoding 2-oxoglutarate-dependent dioxygenases, involved in the formation of the flavonoid aglycon. Musa candidates genes predicted to encode flavanone 3-hydroxylase (F3H), flavonol synthase (FLS) and anthocyanidin synthase (ANS) were assayed. Enzymatic functionalities of the recombinant proteins were confirmed in vivo using bioconversion assays. Moreover, transgenic analyses in corresponding Arabidopsis thaliana mutants showed that MusaF3H, MusaFLS and MusaANS were able to complement the respective loss-of-function phenotypes, thus verifying functionality of the enzymes in planta. Knowledge gained from this work provides a new aspect for further research towards genetic engineering of flavonoid biosynthesis in banana fruits to increase their antioxidant activity and nutritional value.

Highlights

Banana (Musa spp.) plants are well known for their edible fruit and serve as a staple food crop in Africa, Central and South America (Arias et al, 2003)
The approximately maximum-likelihood phylogenetic tree of 33 plant 2-oxoglutarate-dependent dioxygenases (2-ODD) with proven flavanone 3-hydroxylase (F3H), FNSI, flavonol synthase (FLS) and anthocyanidin synthase (ANS) functionality (Supplementary Table S1) and seven Musa 2-ODDs was constructed as described by Pucker et al (2020b): MAFFT alignments were cleaned with pxclsq (Brown et al, 2017) and the tree was constructed with FastTree v2.1.10 using the WAG+CAT model (Price et al, 2010)
This included two F3Hs, four FLSs and one ANS, which were classified as 2-ODDs. To functionally characterise these Musa enzymes, we amplified the corresponding CDSs from a cDNA template collection derived from different Musa organs, using primers designed on the Pahang DH reference genome sequence

Summary

Introduction

Banana (Musa spp.) plants are well known for their edible fruit and serve as a staple food crop in Africa, Central and South America (Arias et al, 2003). Anthocyanins are in many cases well known to colour flowers and fruits to attract animals and promoting pollination and dispersion of seeds (Ishikura and Yoshitama, 1984; Gronquist et al, 2001; Grotewold, 2006). Flavonols can interact with anthocyanins to modify the colour of fruits (Andersen and Jordheim, 2010) and play a prominent role in protection against UV-B irradiation (Li et al, 1993) and in plant fertility (Mo et al, 1992)

Objectives

Methods

Results

Conclusion