How do nitrogen and phosphorus deficiencies affect strigolactone production and exudation?

Plants exude strigolactones (SLs) to attract symbiotic arbuscular mycorrhizal fungi in the rhizosphere. Previous studies have demonstrated that phosphorus (P) deficiency, but not nitrogen (N) deficiency, significantly promotes SL exudation in red clover, while in sorghum not only P deficiency but also N deficiency enhances SL exudation. There are differences between plant species in SL exudation under P- and N-deficient conditions, which may possibly be related to differences between legumes and non-legumes. To investigate this possibility in detail, the effects of N and P deficiencies on SL exudation were examined in Fabaceae (alfalfa and Chinese milk vetch), Asteraceae (marigold and lettuce), Solanaceae (tomato), and Poaceae (wheat) plants. In alfalfa as expected, and unexpectedly in tomato, only P deficiency promoted SL exudation. In contrast, in Chinese milk vetch, a leguminous plant, and in the other non-leguminous plants examined, N deficiency as well as P deficiency enhanced SL exudation. Distinct reductions in shoot P levels were observed in plants grown under N deficiency, except for tomato, in which shoot P level was increased by N starvation, suggesting that the P status of the shoot regulates SL exudation. There seems to be a correlation between shoot P levels and SL exudation across the species/families investigated

Evaluation of phosphorus starvation inducible genes relating to efficient phosphorus utilization in rice

Plants develop strategies to recycle phosphorus so that all organs receive adequate amount of phosphorus, especially new growing organs. To evaluate the metabolic adaptation of rice plant under phosphorus deficient condition, we selected several genes relating phosphorus utilizing efficiency in the cell. Phosphoenolpyruvate carboxylase, triose phosphate translocator, phosphoenolpyruvate/inorganic phosphate translocator (PPT), pyruvate kinase, NAD dependent glyceraldehydes-3-phosphate dehydrogenase, NADP dependent glyceraldehydes-3-phosphate dehydrogenase, were selected because of their important role in the phosphorus utilization in the cell and 2 consisting proposed bypass pathway to save phosphate. Most dramatic change was observed in the expression level of PPT (which tranport phosphoenolpyruvate (PEP) in the cytosol to chloroplast), thus we consider that PEP may play an important role in maintaining carbon metabolism under phosphate deficient condition