The differing responses of two Arabidopsis ecotypes to ammonium are modulated by the photoperiod regime

Abstract

Responses to excessive ammonium (NH 4 ? ) were compared between two Arabidopsis ecotypes (Col-0, JA22) with respect to different photoperiods in hydroponics. In this study, we showed that external extra NH 4 ? led to severe growth suppression, accumulations of free NH 4 ? and amino acids and increased the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in shoots of the two Arabidopsis ecotypes. However, the levels of free NH 4 ? and total amino acids increased, whereas the activities of GS, NADH-dependent glutamate synthase and GDH decreased under the continuous light when compared with the light (16 h)-dark (8 h) cycle photoperiod. Statistical analyses suggested that strong correlations exist among the growth reduction, accumulations of free NH 4 ? , total amino acids and levels of GS activity in shoots under the high NH 4 ? stress regardless of the photoperiod regimes. Interestingly, under the continuous light, Col-0 showed more resistant to such growth reduction and maintained about onefold higher capability of converting excess free NH 4 ? into amino acids, with onefold higher GS activity induced by the external NH 4 ? when compared with JA22. In contrast, these differences were abolished between Col-0 and JA22 under the lightdark cycle condition. Taken together, our results conclude that the sensitivity to NH 4 ? of Col-0 and JA22 is changed between the continuous light and the light-dark cycle photoperiod, which is correlative to the alteration of the GS activity in shoots.

Impaired electron transfer accounts for the photosynthesis inhibition in wheat seedlings (Triticum aestivum L.) subjected to ammonium stress

“…In previous studies, the most obvious inhibition caused by NH 4 + nutrition was reflected by the reduced plant biomass (Li et al , Wang et al , Wang et al ). In the present study, in NH 4 + ‐sensitive AK58, NH 4 + ‐fed plants produced 28.5 and 22.1% lower plant dry biomass and leaf areas, respectively than NO 3 − ‐fed plants.…”

Improvement of nitrogen accumulation and metabolism in rice (Oryza sativa L.) by the endophyte Phomopsis liquidambari

“…These results are consistent with the reports of Liu et al (2013) andP erez-Tienda et al (2014), who showed that the N metabolisms in mycorrhizal roots were significantly changed. Li et al (2011) , and other nutrients from the soil and transport these nutrients to different tissues using a variety of transporters. For example, AMT protein family members transport NH 4 þ , and NRT protein family members transport NO 3 -.…”

Nitrogen use efficiency (NUE) in rice links to NH4 + toxicity and futile NH4 + cycling in roots

“…Nevertheless, NH 4 + frequently reaches levels in soils that affect plant growth negatively. These negative effects manifest in stunted root growth, yield depression, and chlorosis of leaves Balkos et al 2010;Li et al 2011b). However, higher plants display widely differing responses to NH 4 + nutrition (Marschner 1995) and, accordingly, can be divided into tolerant and sensitive species .…”