Low phosphorus availability increases shoot boron concentration in canola and potato but not in wheat

A large proportion of global agricultural soils contain suboptimal available phosphorus (P) for the growth of many plant species. Boron (B) plays important roles in plant growth and development, but limited research has been conducted to study B uptake under low P availability. This study comprised a hydroponic and a mini-rhizobox experiment with canola (Brassica napus L.), potato (Solanum tuberosum L.) and wheat (Triticum aestivum L.) under P sufficient and deficient conditions. Boron concentrations, rhizosphere soil pH, and gene expression of BnBOR1 in canola were determined. Shoot B concentrations were found significantly increased (11-149%) by low P availability in potato and canola but not in wheat. Reverse transcription polymerase chain reaction (RT-PCR) indicated that BnBOR1; 2a, BnBOR1; 2c, and BnBOR1; 3c were up-regulated after seven days of low P treatment in canola roots. Our results indicate that plant shoot B concentration was dramatically influenced by P availability, and dicots and monocots showed a contrasting B concentration response to low P availability.