Expression of the Genes OsNRT1.1, OsNRT2.1, OsNRT2.2, and Kinetics of Nitrate Uptake in Genetically Contrasting Rice Varieties

Osmário J L Araújo,Manlio S Fernandes,Leandro A Santos,Sonia Regina De Souza,André Marques Dos Santos,Milena S Pinto,Elvia M L M Stark,Marcus V L Sperandio

doi:10.4236/ajps.2015.62035

Osmário J L Araújo, Manlio S Fernandes + Show 6 more

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https://doi.org/10.4236/ajps.2015.62035

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Abstract

Four genetically contrasting rice varieties (IAC-47, Bico Ganga, Arroz de Revenda and Manteiga) according to Random Amplified Polymorphic DNA (RAPD) analysis were assessed regarding expression of the genes OsNRT1.1, OsNRT2.1 and OsNRT2.2 and the nitrate uptake kinetics parameters (Km and Vmax). Up to 250-fold increases in the induction of gene expression after nitrate resupply were observed for the high-affinity transporter (OsNRT2.1 and OsNRT2.2). However, no significant variations in Vmax among the varieties were obtained. The lower value of Km of the IAC-47 cultivar in relation to the Arroz de Revenda variety suggests a greater role of high-affinity transporter genes. These results indicate that closer attention should be paid to the expression levels of these genes in selecting varieties aiming to enhance nitrogen uptake efficiency.

Highlights

Rice is a staple food for over half the world’s people, especially in Asia, Africa and Latin America, being especially important for the sustenance of poor people [1]
The polymerase chain reactions (PCRs) were performed in 20 μL of material, containing 25 ng of genomic DNA, 2.3 mM of MgCl2, 0.2 mM of dNTP, 0.2 μM of each primer, one unit of Taq recombinant polymerase DNA (Invitrogen) and 2 μL of the enzyme’s buffer, with the volume completed by adding ultrapure water (Invitrogen), at temperatures according to Areias et al [8]
The genetic similarity dendrogram obtained from the Random Amplified Polymorphic DNA (RAPD) analysis presented two large groups (I and II) (Figure 1)

Summary

Introduction

Rice is a staple food for over half the world’s people, especially in Asia, Africa and Latin America, being especially important for the sustenance of poor people [1]. How to cite this paper: Araújo, O.J.L., et al (2015) Expression of the Genes OsNRT1.1, OsNRT2.1, OsNRT2.2, and Kinetics of Nitrate Uptake in Genetically Contrasting Rice Varieties. In studies of the nitrogen use efficiency, nitrate ( NO3− ) has great importance, because in aerated soils, it is the predominant form available to plants. Previous articles have reported that genetically contrasting rice varieties present variations in the uptake and use of NO3− , affecting the nitrogen use efficiency [4] [5]. Characterization of the kinetics parameters and expression levels of the NO3− transporter genes is important to guide selection of varieties suitable for various growing conditions

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