Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H⁺-ATPases and nitrate transporters in rice

Abstract

Humic acids (HAs) have a major effect on nutrient uptake, metabolism, growth and development in plants. Here, we evaluated the effect of HA pretreatment applied with a nutrient solution on the uptake kinetics of nitrate nitrogen (N-NO 3 − ) and the metabolism of nitrogen (N) in rice under conditions of high and low NO 3 − supply. In addition, the kinetic parameters of NO 3 − uptake, N metabolites, and nitrate transporters (NRTs) and the plasma membrane (PM) H + -ATPase gene expression were examined. The plants were grown in a growth chamber with modified Hoagland and Arnon solution until 21 days after germination (DAG), and they were then transferred to a solution without N for 48 h and then to another solution without N and with and without the addition of HAs for another 48 h. After this period of N deprivation, the plants received new nutrient solutions containing 0.2 and 2.0 mM N-NO 3 − . Treatment of rice plants with HA promoted the induction of the genes OsNRT2.1-2.2/OsNAR2.1 and some isoforms PM H + -ATPase in roots. The application of HAs differentially modified the parameters of the uptake kinetics of NO 3 − under both concentrations. When grown with 0.2 mM NO 3 − , the plants pretreated with HA had lower K m and C min values as well as a higher V max /K m ratio. When grown with 2 mM NO 3 − , the plants pretreated with HA had a higher V max value, a greater root and shoot mass, and a lower root/shoot ratio. The N fractions were also altered by pretreatment with HA, and a greater accumulation of NO 3 − and N-amino was observed in the roots and shoots, respectively, of plants pretreated with HA. The results suggest that pretreatment with HA modifies root morphology and gene expression of PM H + -ATPases and NO 3 − transporters, resulting in a greater efficiency of NO 3 − acquisition by high-and low-affinity systems.

A Vegetal Biopolymer-Based Biostimulant Promoted Root Growth in Melon While Triggering Brassinosteroids and Stress-Related Compounds

“…In their study Ertani et al (2011) demonstrated that lignosulphonates treatment improved N assimilation in maize plants through the stimulation of key enzymes (glutamate-synthase and glutamine-synthetase) and also by promoting photosynthetic activity through the stimulation of both rubisco enzyme activity as well as chlorophyll biosynthesis. Besides the biostimulant-mediated enhancement of root growth, vegetal-based biopolymers can also upregulate the expression of genes encoding for plasma membrane H + -ATPases and nitrate transporters, resulting in greater efficiency in nitrate uptake and assimilation ( Tavares et al, 2017 ).…”

Nutrient acquisition and eucalyptus growth affected by humic acid sources and concentrations

“…There was a decline in Ca uptake efficiency with the increase in C-HA concentration. The HS are able to optimize nutrient acquisition by plants, whether by stimulation of cell transporters that increase P uptake (JINDO et al, 2016), or stimulation of plasmatic membrane H + -ATPase, generating an electrochemical difference of protons between it and the outside medium which increases nutrient uptake (CANELLAS et al, 2015), including N acquisition by plants (TAVARES et al, 2017). HS acts stimulating the number of physiologically active roots (RIMA et al, 2011) and increase root growth (MELO et al, 2015;ROSE et al, 2014), Such effects depends on the HA concentration and properties (AGUIAR et al, 2009).…”

“…According to Pinheiro et al (2010), increase in HA concentration in nutrient solution drastically reduced accumulation of Fe, Cu, and Zn; however, for Mn, this effect was not so pronounced as for Fe, Cu, Zn and B; depending on the source, Mn accumulation improves when the concentration of 10 mg L -1 C-HA is used. Application of HA increasing macronutrient accumulation in plants is shown in greater magnitude for N, P, K, and Ca (AZCONA et al, 2011;EKINCI et al, 2015;MELO et al 2015;TAVARES et al, 2017), whereas, for S and Mg, this effect may be small or null (AZCONA et al, 2011;PINHEIRO et al, 2010).…”

“…Besides, HA increases number of physiologically active root (RIMA et al, 2011), and improves the plasmatic membrane H + -ATPase activity (NARDI et al, 2016). In addition, HA can stimulate nutrient transporter activity (JINDO et al, 2016;TAVARES et al, 2017;TOMASI et al, 2014). Indirect effects are those associated with the ability of HA to change the growth medium pH and electrical conductivity (EC) and nutrient complexation, changing macro and micro nutrients availability (LYONS; GENC, 2016;PINHEIRO et al, 2010).…”

Estímulo da atividade das H+-ATPases por Enterobacter sp. em mudas de Calophyllum brasiliense Cambess (guanandi)

“…Outra contribuição importante dos MPVC para a nutrição radicular é a estimulação de enzimas como as H + -ATPases da membrana plasmática, que convertem a energia livre liberada pela hidrólise do ATP em um potencial eletroquímico trans-membranar usado para a importação de nitrato e outros nutrientes (Du Jardin, 2015). Além da captação de nutrientes, o bombeamento de prótons pelas ATPases da membrana plasmática também contribui para o afrouxamento da parede celular e o aumento celular levando a maiores rendimentos por parte da planta (Zandonadi et al, 2010(Zandonadi et al, , 2016Tavares et al, 2017).…”