pH
Soil acidity or pH directly and indirectly influences root
development. Plant roots respond to changes in soil pH with
massive transcriptional alterations in the expression of a large
number of auxin-responsive genes, suggesting that pH-mediated
changes in root architecture are at least partly mediated by auxin
(Lager et al., 2010). Plant roots grown under alkaline conditions
(e.g. pH 8) show increased auxin transport activity mediated by
PIN2 (Xu W et al., 2012). PIN2-transported auxin is also
required for the activation of plasma membrane H+-ATPasemediated
proton secretion from the root tips. This process
appears to be essential in acidifying the environment around
the roots and maintaining primary root growth (Xu W et al.,
2012). Additional studies are certainly required to dissect the
effect of pH on root development and the potential roles of
auxin signalling and transport in the integration of pH-mediated
effects into root architectur