Purpose
Nitrogen (N) and sulphur (S) are essential for plant growth and development. Cysteine (Cys) and methionine (Met) are N- and S-containing amino acids in soils. However, it is unclear whether plants possess a strong ability to utilise N- and S-containing amino acids from the plant physiology perspective, and whether they can access amino acids when facing rapid microbial decomposition in the soil.
Methods
Wheat and oilseed rape were cultivated using a sterilised hydroponic solution in the laboratory and field conditions with 13C-, 14C-, 15N-, and 35S-labelled Cys and Met.
Results
With sterilised hydroponic cultivation, wheat and oilseed rape possessed a greater ability for Cys and Met uptake than for SO42− uptake, but these compounds did not support plant growth at high concentrations. The uptake rate of Cys and Met in oilseed rape was almost 20-fold higher than that in wheat, while the transportation ratio was even higher, indicating that oilseed rape not only possesses a great ability for S-containing amino acid uptake but also metabolises and transports them to the shoot quickly. A short-term labelling uptake test (6 h) in the field showed that 0.6–2.2% of total added Cys and Met were utilised by wheat and oilseed rape in the intact form owing to fierce competition from soil microorganisms.
Conclusions
Wheat and oilseed rape possess a great ability for Cys and Met uptake but can access limited amounts owing to rapid microbial decomposition in soil.