Physiological dissection revealed that both uptake and assimilation are the major components regulating different growth responses of two tobacco cultivars to nitrogen nutrition

Abstract

K326 and HD represent major tobacco cultivars in China, which required large N fertiliser input but at different application rates. To understand primary components affecting tobacco N use physiology, we adopted these two varieties as valuable genetic material to assess their growth response to N nutrition. We established a hydroponic culture system to grow plants supplied with different N regimes. Plant biomass, N, ammonium, nitrate, arginine, GS and NR activity, N transfer and use efficiency as well as root uptake were examined. Our data revealed the preference of K326 and HD to utilise nitrate or ammonium nitrate but not ammonium alone, with 2 mm N supply probably sufficient and economical to achieve good biomass production at the vegetative stage. Moreover, both varieties were very sensitive to ammonium, perhaps due to lack of or abnormal signalling related to nitrate and/or arginine rather than impairment of N acquisition and initial assimilation; this was supported by measurements of the plant content of N, ammonium and activities of GS and NR. Notably, short-term N root influx studies identified differential uptake kinetics of K326 and HD, with distinct affinities and transport rates for ammonium and nitrate. The data suggest that the growth adaptation of K326 or HD to higher or lower N may be ascribed to different competences for effective N uptake/translocation and assimilation. Thus, our work provides valuable information to prompt deeper investigation of the molecular basis controlling plant N use efficiency.

Molecular identification and functional characterization of GhAMT1.3 in ammonium transport with a high affinity from cotton (Gossypium hirsutum L.)

“…In this work, we revealed that cotton roots preferentially absorb ammonium when presented equimolarly with nitrate in the medium (Fig. A), despite being an unfavorable N‐source for the growth of some crops, including cotton plants, when grown solely with NH 4 + as N form (Gerendás et al , Britto and Kronzucker , Fan et al ). Subsequently, we have for the first time provided kinetic evidence for cotton NH 4 + acquisition.…”

Genotypic Variation in Nitrogen Use-Efficiency Traits of 28 Tobacco Genotypes

“…Indeed, Poorter et al [25] relate the challenge of assessing a reliable mass of roots in plants conducted in pot experiments with substrate. Fan et al [15] found a decrease of root/shoot ratio with increasing N concentration for one cultivar, but not in another one when supplied solely with N-NO 3 . However, our data are in accordance with the "functional equilibrium" existing between roots and shoots described by Brouwer [26].…”

“…For tobacco genotypes, few works have used numerous genotypes in the study of NUE traits [13,14]. Thus, studies of the mechanisms behind NUE traits are limited to a few tobacco genotypes [15,16]. Again, this is comprehensive, since the growing process of many genotypes is time-intensive in terms of labor, and plant analysis is frequently time consuming with associated high costs (e.g., physiological analysis, 15 N isotypes).…”

Juvenile hormone mediates the positive effects of nitrogen fertilization on weight and reproduction in pea aphid

“…Plants show great genetic variation in nitrogen uptake, translocation and assimilation, and in conversion of the assimilated products into amino acids and other nitrogen‐containing compounds, which results in distinct responses in nitrogen and amino acid contents to nitrogen fertilization among plant species . For example, tobacco K326 has higher foliar nitrogen content under nitrate fertilization than tobacco HD, which is due to the higher activity of nitrate reductase and nitrite reductase . Thus, insects feeding on the different plants could have various responses to nitrogen fertilization .…”

“…[8][9][10] For example, tobacco K326 has higher foliar nitrogen content under nitrate fertilization than tobacco HD, which is due to the higher activity of nitrate reductase and nitrite reductase. 11 Thus, insects feeding on the different plants could have various responses to nitrogen fertilization. 12 Moreover, the existence of an optimal plant nitrogen level for herbivorous insects has been proposed, and this differs among insect species.…”