Arabidopsis NRT1.5 is another essential component in the regulation of nitrate reallocation and stress tolerance.
Nitrate reallocation to plant roots occurs frequently under adverse conditions and was recently characterized to be actively regulated by Nitrate Transporter1.8 (NRT1.8) in Arabidopsis (Arabidopsis thaliana) and implicated as a common response to stresses. However, the underlying mechanisms remain largely to be determined. In this study, characterization of NRT1.5, a xylem nitrate-loading transporter, showed that the mRNA level of NRT1.5 is down-regulated by salt, drought, and cadmium treatments. Functional disruption of NRT1.5 enhanced tolerance to salt, drought, and cadmium stresses. Further analyses showed that nitrate, as well as Na(+) and Cd(2+) levels, were significantly increased in nrt1.5 roots. Important genes including Na(+)/H(+) exchanger1, Salt overly sensitive1, Pyrroline-5-carboxylate synthase1, Responsive to desiccation29A, Phytochelatin synthase1, and NRT1.8 in stress response pathways are steadily up-regulated in nrt1.5 mutant plants. Interestingly, altered accumulation of metabolites, including proline and malondialdehyde, was also observed in nrt1.5 plants. These data suggest that NRT1.5 is involved in nitrate allocation to roots and the consequent tolerance to several stresses, in a mechanism probably shared with NRT1.8.
National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, People's Republic of China.
Chun-Zhu
CZ
Chen
Xin-Fang
XF
Lv
Jian-Yong
JY
Li
Hong-Ying
HY
Yi
Ji-Ming
JM
Gong
D000222:Adaptation, Physiological / Q000235:genetics; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D055442:Metabolome / Q000235:genetics; D009154:Mutation / Q000235:genetics; D009566:Nitrates / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics
D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; C539716:NRT1.5 protein, Arabidopsis; D009566:Nitrates; D002104:Cadmium; D012964:Sodium