Over-expression of TaDWF4 increases wheat productivity under low and sufficient nitrogen through enhanced carbon assimilation

Matthew J Milner,Alison R Bentley,Stéphanie M Swarbreck,Howard Griffiths,Emma J Wallington,Sarah Bowden,Melanie Craze

doi:10.1038/s42003-022-03139-9

Abstract

There is a strong pressure to reduce nitrogen (N) fertilizer inputs while maintaining or increasing current cereal crop yields. We show that overexpression of TaDWF4-B, the dominant shoot expressed homoeologue of OsDWF4, in wheat can increase plant productivity by up to 105% under a range of N levels on marginal soils, resulting in increased N use efficiency (NUE). We show that a two to four-fold increase in TaDWF4 transcript levels enhances the responsiveness of genes regulated by N. The productivity increases seen were primarily due to the maintenance of photosystem II operating efficiency and carbon assimilation in plants when grown under limiting N conditions and not an overall increase in photosynthesis capacity. The increased biomass production and yield per plant in TaDWF4 OE lines could be linked to modified carbon partitioning and changes in expression pattern of the growth regulator Target Of Rapamycin, offering a route towards breeding for sustained yield and lower N inputs.

Highlights

Seven amino acid sequences were identified with high homology to the rice DWF4 amino acid sequence (e value < 1e−50, and >70% homology), these were encoded by four sequences located on chromosome 3 and three sequences located on chromosome 4
In this study, we identified the functional orthologues of the OsDWF4 in wheat and generated OE lines to understand whether increased TaDWF4 expression could be used to increase wheat N use efficiency (NUE) and drive an increase in yield as seen in other crops with modified DWF4 expression
Significant tissue type differences were seen in the expression of the three homoeologues, suggesting that specific regulatory elements may control modification of TaDWF4 expression in particular tissues to increase plant growth in wheat

Summary

Introduction

There is a strong pressure to reduce nitrogen (N) fertilizer inputs while maintaining or increasing current cereal crop yields. Strategies to improve the yield capacity of crop cultivars have focused on photosynthesis[8–10], with gains in biomass and yield reaching 40%11,12 This is not sufficient, and reducing our reliance on synthetic fertilizer will rely on identifying ways to reduce wheat N requirement, i.e., being able to produce wheat with lower N input without a reduction in yield or grain quality[2]. The presence of homeoalleles in hexaploid wheat increases both coding sequence variation per se and regulatory variation with the new promoter and transcription factor combinations and functional diversification of the duplicated genes[21,22] This genome asymmetry and variation have consequences for quality traits such as the control of wheat seed storage proteins, biotic and abiotic traits, agronomic traits, and response to pests and diseases[23–25]. The mechanism of how altering BR levels impacts yield is still not completely understood, but in many plant species an increased rate of carbon fixation has been observed, suggesting that photosynthesis is key to the increased yields[30,34]

Methods

Results

Conclusion