Mild ammonium stress increases chlorophyllcontent inArabidopsis thaliana

摘要

Nitrate (NO3) and ammonium (NH4C) are the main forms of nitrogen available in the soil for plants. Excessive NH4Caccumulation in tissues is toxic for plants and exclusive NH4C-based nutrition enhances this effect. Ammonium toxicitysyndrome commonly includes growth impairment, ion imbalance and chlorosis among others. In this work, weobserved high intraspecific variability in chlorophyll content in 47Arabidopsis thaliananatural accessions grown under1mM NH4Cor 1 mM NO3 as N-source. Interestingly, chlorophyll content increased in every accession uponammonium nutrition. Moreover, this increase was independent of ammonium tolerance capacity. Thus, chlorosis seemsto be an exclusive effect of severe ammonium toxicity while mild ammonium stress induces chlorophyll accumulation.