Phenotypical evidence of effective amelioration of ammonium-inhibited plant (root) growth by exogenous low urea

• Published in: Journal of plant physiology 2020-12, Vol.255, p.153306, Article 153306
• Main Authors: Ke, Jie, Pu, Wen-Xuan, Wang, Hui, Liu, Lai-Hua, Sheng, Song
• Format: Article
• Language: English
• Subjects: Ammonium; Ammonium Compounds - adverse effects; Ammonium Compounds - metabolism; Ammonium tolerance Cotton; Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Cotton; Crops, Agricultural - genetics; Crops, Agricultural - growth & development; Crops, Agricultural - metabolism; Detoxification; Exogenous urea; Gene Expression Regulation, Plant - drug effects; Genetic Variation; Gossypium - genetics; Gossypium - growth & development; Gossypium - metabolism; Growth rate; Nitrogen; Nitrogen sources; Phenotype; Plant growth; Plant Roots - growth & development; Plant Roots - metabolism; Root growth; Tobacco; Urea; Urea - metabolism; Urea - pharmacology
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2020.153306

•Sub-millimolar urea effectively improves NH4+-inhibited plant/root growth of different species. Ammonium and nitrate are major soil inorganic-nitrogen sources for plant growth, but many species cultivated with even low millimolar NH4+ as a sole N form display a growth retardation. To date, critical biological components and applicable approaches involved in the effective enhancement of NH4+ tolerance remain to be thoroughly explored. Here, we report phenotypical traits of urea-dependent improvement of NH4+-suppressed plant/root growth. Urea at 0.1 mM was sufficient to remarkably stimulate NH4+ (3 mM)-fed cotton growth, showing a 2.5∼4-fold increase in shoot- and root-biomass and total root-length, 20 % higher GS activity, 18 % less NH4+-accumulation in roots, and a comparable plant total-N content compared to the control, implying a novel role for urea in cotton NH4+detoxification. A similar phenomenon was observed in tobacco and rice. Moreover, comparisons between twelve NH4+-grown Arabidopsis accessions revealed a great degree of natural variation in their root-growth response to low urea, with WAR and Blh-1 exhibiting the most significant increase in primary- and lateral-root length and numbers, and Sav-0 and Edi-0 being the most insensitive. Such phenotypical evidence suggests a common ability of plants to accommodate NH4+-stress by responding to exogenous urea, providing a novel aspect for further understanding the process of urea-dependent plant NH4+ tolerance.