It is only a posteriori that PSTOL1, the isolated gene underlying PUP1 QTL, proved to control an adaptive development response of the root system in low-phosphate soil condition promoting root branching (Gamuyao et al. [2012]).
The variables which control the reaction of phosphate in soil are the solubility of fertilizers, the inorganic or organic form, soil pH, presence of calcareous materials and water management practices (Ranjan et al. 2013).
It has been estimated that 5·7 billion hectares of land worldwide are deficient in P. Concentrations of phosphate in soil solutions are generally <10 µ m, which are well below the critical level that is needed for the optimal performance of crops (Batjes, 1997).
But pollution specialists are more interested in the calcium in the gypsum; it binds with phosphate in soil, forming a larger particle that resists being washed away.
The mobility of phosphate in soil and aquatic systems is largely determined by the reaction between phosphate and mineral surfaces [3, 4].
Plants grown in phosphate deficient soil have shown increased strigolactones production which facilitate root growth development and fungal/mycorrhizal symbiosis increasing phosphate intake from the rhizosphere.
Biotechnology research aimed at reducing input requirements and increasing input use efficiency could lead to crops that utilize water more efficiently, fix nitrogen from air, extract phosphate from soil more effectively, and resist pests without synthetic pesticides.
Compounds with carboxylic acid groups were selected because the effect of organic anions on the mobilization of phosphate in soil is mediated by their functional groups [ 25], among which carboxyls are known to play a central role [ 26].
Also, twenty to eighty percent of phosphate in soil is in organic form [ 3]; it should be mineralized into inorganic form before it becomes available for plant up-taking.
