Int. J. Dev. Biol. 63: 45 - 55 (2019)
doi: 10.1387/ijdb.180360mv
© UPV/EHU Press

Functional analysis of Arabidopsis and maize transgenic lines overexpressing the ADP-ribose/NADH pyrophosphohydrolase, AtNUDX7

Elizabeth Njuguna1,2, Griet Coussens1,2, Pia Neyt1,2, Stijn Aesaert1,2, Veronique Storme1,2, Kirin Demuynck1,2, Hannes Vanhaeren1,2, Stijn Dhondt1,2, Yolaine Van Haver1,2, Linus Paul1,2, Dirk Inzé1,2, Hilde Nelissen1,2 and Mieke Van Lijsebettens*,1,2

1Department of Plant Biotechnology and Bioinformatics, Ghent University and 2Center for Plant Systems Biology, VIB, Gent, Belgium

ABSTRACT The conserved poly(ADP-ribosyl)ation (PAR) pathway consists of three genetic components that are potential targets to modulate the plant’s energy homeostasis upon stress with the aim to improve yield stability in crops and help secure food supply. We studied the role of the PAR pathway component ADP-ribose/NADH pyrophosphohydrolase (AtNUDX7) in yield and mild drought stress by using a transgenic approach in Arabidopsis thaliana and maize (Zea mays). Arabidopsis AtNUDX7 cDNA was overexpressed in Arabidopsis and maize by means of the constitutive Cauliflower Mosaic Virus 35S promoter and the strong constitutive Brachypodium distachyon pBdEF1α promoter, respectively. Overexpression of AtNUDX7 in Arabidopsis improved seed parameters that were measured by a novel, automated method, accelerated flowering and reduced inflorescence height. This combination of beneficial traits suggested that AtNUDX7 overexpression in Arabidopsis might enhance the ADP-ribose recycling step and maintain energy levels by supplying an ATP source in the poly(ADP-ribosyl)ation energy homeostasis pathway. Arabidopsis and maize lines with high, medium and low overexpression levels of the AtNUDX7 gene were analysed in automated platforms and the inhibition of several growth parameters was determined under mild drought stress conditions. The data showed that the constitutive overexpression of the Arabidopsis AtNUDX7 gene in Arabidopsis and maize at varying levels did not improve tolerance to mild drought stress, but knocking down AtNUDX7 expression did, however at the expense of general growth under normal conditions.

Keywords:

seed yield, flowering time, water deficit, mild drought stress, constitutive promoter

*Corresponding author e-mail: milij@psb.vib-ugent.be