Agriculture Reference
In-Depth Information
QTLs in several crop species. Nonetheless, its practical and effective application in
MAS of breeding programmes has been rather limited up to now and would require
higher precision, reliability and a proof of consistency across these known QTLs.
Additionally, these findings emphasise the previously mentioned importance of
post-transcriptional modification in the sensing and signalling network of P homeo-
stasis, the low P tolerance, and the association of low P tolerance with root
morphology.
Conclusions
Phosphorus is an essential macronutrient with crucial functions in plant
macromolecular structure, energy metabolism and signal transduction,
which can be a major constraint for high yield when it becomes limiting in
crop production. There are economic, political and environmental reasons
why P efficiency (PAE, PUE) and P fertiliser use in crops should be inves-
tigated for future crop improvement. Therefore, scientific interest has
increased with the aim of finding the underlying molecular mechanisms for
adaptation to low P accessibility and of identifying targets to archive high-
yielding, low P-tolerant crops. Agronomic strategies for raising the amount of
available fertiliser are constantly under assessment but the polygenetic basis
of P deficiency tolerance is not yet understood. Field selection and screening
for PAE/PUE traits, especially in relation to roots, are difficult to realise due
to the complexity of soil P and agronomic practice, which may have signif-
icant impact on P availability and root properties. Another critical point is the
shift from P acquisition to translocation processes when crops become gen-
erative and distribution in grain and seeds becomes predominant. Several
approaches for investigating crops, such as the comparison of individual
genotypes exposed to a short-term P starvation period, the over-expression
of target genes and QTL analysis have resulted in contradictory observations.
Nevertheless many potential target genes, which have been identified previ-
ously in model organisms using forward and reverse genetic approaches, are
also be found in crops and are potentially exploitable. Phosphate transporters,
several transcription factors, genes coding for proteins of the TCA cycle
metabolism, phospholipid degradation, transfer and post-translational modi-
fications are among the candidates who have been detected even if their role
in the genetically diverse low P tolerance or PAE/PUE context seems com-
plex and still rather elusive.
Acknowledgements Work at Rothamsted Research is supported via the 20:20 Wheat
®
Programme by the UK Biotechnology and Biological Sciences Research Council. The contribu-
tion of A. Gruen was supported by which received funding from the European Union Seventh
Framework Programme (FP7/2007-2013) under grant agreement n
264296.
