Activation of polyphenol oxidase in dormant wild oat caryopses by a seed-decay isolate of Fusarium avenaceum.
Incubation of dormant wild oat (Avena fatua L., isoline M73) caryopses for 1-3 days with Fusarium avenaceum seed-decay isolate F.a.1 induced activity of the plant defense enzyme polyphenol oxidase (PPO). Both extracts and leachates obtained from F.a.1-treated caryopses had decreased abundance of an ∼57 kDa antigenic PPO and increased abundance of antigenic PPOs ranging from ∼52 to 14 kDa, as compared to extracts and leachates from untreated caryopsis. Leachates from caryopsis incubated for 2 days with F.a.1 also had 5.1- and 7.5-fold more total PPO activity/g fwt and specific activity, respectively. Fractionation of leachate proteins by ion-exchange chromatography associated the majority of PPO activity with an ∼36 kDa protein from untreated caryopses and ∼36, 25, and 24 kDa proteins from F.a.1-treated caryopses. Predicted peptide sequences obtained from high-performance liquid chromatography-tandem mass spectrometry analyses indicated that the ∼57 and 36 kDa wild oat proteins had a strong similarity to wheat PPO. However, the 25 and 24 kDa proteins were most similar to a Chitinase and oxalate oxidase, respectively. Our results indicate that F.a.1-induced activation of latent PPO in wild oat caryopsis likely involves a cleavage mechanism allowing activated PPOs to be readily mobilized into their surrounding environment.
Anderson
James V
JV
Biosciences Research Laboratory, Agricultural Research Service, US Department of Agriculture, 1605 Albrecht Boulevard, Fargo, North Dakota 58102-2765, USA. james.anderson@ars.usda.gov
Fuerst
E Patrick
EP
Tedrow
Trisa
T
Hulke
Brent
B
Kennedy
Ann C
AC
D000595:Amino Acid Sequence; D004156:Catechol Oxidase / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004789:Enzyme Activation; D005670:Fusarium / Q000502:physiology*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000302:isolation & purification; D006109:Poaceae / Q000201:enzymology*; D012639:Seeds / Q000201:enzymology* / Q000382:microbiology*; D053719:Tandem Mass Spectrometry
D010940:Plant Proteins; D004156:Catechol Oxidase