Drought stress increases the production of 5-hydroxynorvaline in two C4 grasses.
Plants produce various compounds in response to water deficit. Here, the presence and identification of a drought-inducible non-protein amino acid in the leaves of two C(4) grasses is first reported. The soluble amino acids extracted from the leaves of three different species were measured by high-performance liquid chromatography of derivatives formed with o-phthaldialdehyde and beta-mercaptoethanol. One amino acid that increased in amount with drought stress had a retention time not corresponding to any common amino acid. Its identity was determined by metabolite profiling, using (1)H NMR and GC-MS. This unusual amino acid was present in the dehydrated leaves of Cynodon dactylon (L.) Pers. and Zoysia japonica Steudel, but was absent from Paspalum dilatatum Poir. Its identity as 2-amino-5-hydroxypentanoic acid (5-hydroxynorvaline, 5-HNV) was confirmed by synthesis and co-chromatography of synthetic and naturally occurring compounds. The amount of 5-HNV in leaves of the more drought tolerant C(4) grasses, C. dactylon and Z. japonica, increased with increasing water deficit; therefore, any benefits from this unusual non-protein amino acid for drought resistance should be further explored.
Centro de Engenharia Biológica and Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal. elizabete.carmosilva@gmail.com
Ana E
AE
Carmo-Silva
Alfred J
AJ
Keys
Michael H
MH
Beale
Jane L
JL
Ward
John M
JM
Baker
Nathaniel D
ND
Hawkins
Maria Celeste
MC
Arrabaça
Martin A J
MA
Parry
D000596:Amino Acids / Q000096:biosynthesis*; D055864:Droughts; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D006109:Poaceae / Q000378:metabolism*; D013045:Species Specificity
D000596:Amino Acids; C004387:2-amino-5-hydroxyvaleric acid