Hypothesis/review: contribution of putrescine to 4-aminobutyrate (GABA) production in response to abiotic stress.
4-Aminobutyrate (GABA) accumulates in various plant parts, including bulky fruits such as apples, in response to abiotic stress. It is generally believed that the GABA is derived from glutamate, although a contribution from polyamines is possible. Putrescine, but not spermidine and spermine, generally accumulates in response to the genetic manipulation of polyamine biosynthetic enzymes and abiotic stress. However, the GABA levels in stressed plants are influenced by processes other than putrescine availability. It is hypothesized that the catabolism of putrescine to GABA is regulated by a combination of gene-dependent and -independent processes. The expression of several putative diamine oxidase genes is weak, but highly stress-inducible in certain tissues of Arabidopsis. In contrast, candidate genes that encode 4-aminobutyraldehyde dehydrogenase are highly constitutive, but not stress inducible. Changes in O(2) availability and cellular redox balance due to stress may directly influence the activities of diamine oxidase and 4-aminobutyraldehyde dehydrogenase, thereby restricting GABA formation. Apple fruit is known to accumulate GABA under controlled atmosphere storage and therefore could serve as a model system for investigating the relative contribution of putrescine and glutamate to GABA production.
Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1. Electronic address: bshelp@uoguelph.ca.
Barry J
BJ
Shelp
Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Gale G
GG
Bozzo
Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Christopher P
CP
Trobacher
Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Adel
A
Zarei
Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Kristen L
KL
Deyman
Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Carolyne J
CJ
Brikis
D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018698:Glutamic Acid / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011700:Putrescine / Q000378:metabolism*; D013312:Stress, Physiological; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis* / Q000235:genetics
D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D011700:Putrescine