Abstract
Phosphorous is the second abundantly required nutrient for most crop plants, and is the most limited nutrient in natural soil. On the other hand, phosphorous in crop fields forms both insoluble organic and inorganic compounds due to its chemical properties. Taken together, P-limitation is one of the most serious factors that reduce crop yield in local farming system of developing countries, while over-input of P-fertilizer would be one of the problems for that of developed countries. In this situation, improvement of tolerance of crops to P-limited environment is one of the most important targets in molecular breeding. In fact, several procedures of molecular breeding to this target were proposed in late 90's, while almost of all attempts were limited in model plant system. In the current talk, I will focus on recent progress in plant molecular physiology that may enable "real-improvement" of tolerance of crop plants to P-limited condition. This will include 1) molecular mechanisms of organic acid excretion from the roots, 2) internal P-recycling system and 3) plant-microbial interaction for efficient P-acquisition.
