**Acknowledgements**

is evident. Namely, hexaploid bread wheat (*Triticum aestivum* L.) has one of the most complex (ABD) genomes (e.g. six copies of each chromosome, numerous of near-identical sequences scattered throughout, overall haploid size of >15 billion bases) [100], thus making wheat highly challenging for genome sequencing and detection of salt-tolerant genes and quantitative trait loci. Also, the huge amount of repetitive sequences poses a big challenge for sequencing the wheat genome [101]. For instance, first assembly of the wheat genome from 2012 was represented by only ~33% (5.42 billion bases) [102], another assembly from 2014 by ~66% (10.2 billion bases) [103] whereas assemblies from 2017 were extended to 78% (12.7 billion bases) [104] and recent assembly was almost completed with >15.3 billion bases [100]. Hence, the genomic complexity and its uncomplete assembly makes the wheat crop additionally extremely difficult for improvement to salt tolerance over conventional (e.g. traditional breeding) and/or modern genetic (e.g. molecular and transgenic breeding) approaches.

Genetic improvement of wheat for salt-tolerance has also a great potential of acquiring some

wheat genotypes with genetically related halophytic plant species (e.g. *Lophopyrum elongatum*) [105]. In wheat salt resistance is associated with low rates of the root-to-shoot transport

on chromosome 4D [107]. Contrary, durum wheat (tetraploid, AB genomes) have higher rates

Sustainable plant production has three main goals: environmental health, economic profitability, and social and economic equity. It needs to achieve higher and higher amount of quality food by using less stock and energy under actual environmental conditions. Nitrogen is one of the most important nutrients for plants because of the yield quality and quantity as well. Applying adequate amount of nutrients based on genotype requirements is hard under potential conditions, especially under different abiotic loads. About 70% of all fertilisers are used on wheat and rice. Wheat is an important staple crop and crucial source of non-animal protein in human food and also makes a significant contribution to animal feed. The problem is that the utilisation efficiency of nitrogenous fertilisers under field conditions is relatively low, thus the production may become dangerous for the environment, economically inadequate and can result in poor quality. Finding of 'smart' wheat genotypes with high NUE does not mean a solution for the problem of being sustainable. Several environmental conditions have effect on NUE and/or the components

of NUE, thus we need more knowledge to locate the final answer our global challenge.

 accumulation and weaker K+/Na + discrimination [80] and is consequently less salt resistant *vs*. bread wheat (**Figure 2**). It was confirmed that salt−/draught-tolerant genes and quantitative trait loci identified in *T. dicoccoides* and *H. spontaneum* have great potential in wheat improvement also [108]. Finally, improvement in salt resistance of modern wheat genotypes will be generated from introducing new gene(s) by (i) crossing with new donor germplasm or (ii) transformation with single genes, and after the progeny has to be back-crossed

exclusion and/or compartmentation by crossing

[106]. Bread wheat genotypes have a low rate of

discrimination which is controlled by a locus (Kna1)

/Cl<sup>−</sup>

over Na+

/Na+

into adapted cultivars before the donor genes are ready for cultivation [80].

halophytic traits (genes) such as Na+

with high selectivity for K+

accumulation and enhanced K+

of Na+

40 Global Wheat Production

of Na+

**6. Conclusion**

Na+

Thank you for the support of 'Kiváló malomipari paraméterekkel rendelkező adaptív őszi búza vonalak előállítása' (AGR\_PIAC\_13-1-2013-0002) grant and the EFOP-3.6.3- VEKOP-16- 2017-00008 project. The project is co-financed by the European Union and the European Social Fund.
