Molecular and genomic studies have shown the presence of a large number of
SPX
gene family members in plants, some of which have been proved to act in P signalling and homeostasis. In this study, the molecular and evolutionary characteristics of the
SPX
gene family in plants were comprehensively analysed, and the mechanisms underlying the function of
SPX
genes in P signalling and homeostasis in the model plant species
Arabidopsis
(
Arabidopsis thaliana
) and rice (
Oryza sativa
), and in important crops, including wheat (
Triticum aestivum
), soya beans (
Glycine max
) and rapeseed (
Brassica napus
), were described. Emerging findings on the involvement of
SPX
genes in other important processes (i.e. disease resistance, iron deficiency response, low oxygen response and phytochrome-mediated light signalling) were also highlighted. The available data suggest that
SPX
genes are important regulators in the P signalling network, and may be valuable targets for enhancing crop tolerance to low P stress. Further studies on SPX proteins should include more diverse members, which may reveal SPX proteins as important regulatory hubs for multiple processes including P signalling and homeostasis in plants.
Jasmonate signalling network in Arabidopsis thaliana: crucial regulatory nodes and new physiological scenarios
