Expression of AMT1;1 and AMT2;1 is stimulated by mineral nitrogen and reproductive growth stage in barley under field conditions

Abstract

Barley (Hordeum vulgare) is an important cereal for providing food and feed. Nitrogen (N) is a crucial element for plant productivity. N fertilizing management requires large amount of money and energy, and excess application makes environmental hazards. Therefore, the future varieties and management systems need to be more efficient in nitrogen uptake and utilization. Ammonium transporters (AMTs) are important genes in N uptake and transport. Since N has strong impact on biomass production, it was hypothesized that N rate and barley growth stage have significant influence on AMT expression under field conditions. The field experiment was carried out in 2019 to determine expression patterns of HvAMT1;1 and HvAMT2;1 genes at different growth stages under different N fertilizer rates and types. A down-regulation of HvAMT1;1 and HvAMT2;1 until heading and up-regulation at anthesis stage was observed compared to the unfertilized treatment, mineral fertilizers having stronger effect. HvAMT1;1 was expressed 2.8 times more than HvAMT2;1 at the same time. There was a positive correlation between both AMT genes expression and N content in leaves at anthesis as well as 1000-kernel weight. In conclusion, nitrogen uptake and translocation is partially governed by HvAMT1;1 and HvAMT2;1, and it is a valuable candidate for breeding programs.

Keywords:

• ammonium transporter
• nitrogen
• barley
• conventional
• organic
• manure
• gene expression

Acknowledgments

Many thanks to the crop science team, especially to Enn Lauringson, Are Selge, Liina Talgre, Maarika Alaru and Vyacheslav Eremeev who have contributed towards the experiment initiation and management. The technical assistance of Rõhu experimental station from the Estonian University of Life Sciences is gratefully acknowledged.

Disclosure statement

The authors declare that there are no conflicts of interest.

Additional information

Funding

This research was supported by the Estonian Research Council grant PRG 1260. The study has also been supported by Estonian University of Life Sciences projects P180270PKTT and P190257PKTT.