Strawberry fruit protein with a novel indole-acyl modification

Area of Science:

• Plant Biochemistry
• Molecular Biology
• Fruit Development

Background:

• Plant hormones, particularly auxins like indole-3-acetic acid (IAA), play crucial roles in plant growth and development.
• Conjugation of IAA to other molecules can affect its activity, transport, and storage within plant tissues.
• Previous research has identified various IAA conjugates, but protein-bound forms in fruit tissues remain less explored.

Purpose of the Study:

• To investigate the presence and nature of solvent-insoluble conjugated indole-3-acetic acid (IAA) in Fragaria vesca (strawberry) achenes and receptacle tissue.
• To identify the molecular identity of the protein to which IAA is conjugated in strawberry fruit.
• To characterize the class of IAA conjugates present in strawberry fruit tissue.

Main Methods:

• Extraction and alkaline hydrolysis of conjugated IAA from strawberry achenes and receptacles.
• Production of a polyclonal antibody against IAA-glycine-BSA to detect IAA conjugates.
• Immunoblotting to detect immuno-reactive bands, followed by 2D-PAGE and LC-MS/MS analysis for protein identification.

Main Results:

• Solvent-insoluble conjugated IAA was detected in both achenes and receptacles, accounting for 0.4-4 ng IAA per gram fresh weight.
• Immunoblotting revealed a prominent immuno-detectable band at approximately 76 kDa in strawberry tissues.
• LC-MS/MS analysis of peptides from this band tentatively identified proteins related to chaperonin (hsp60) or ATP synthase.

Conclusions:

• This study reports the first evidence of IAA modified protein in fruit tissue, specifically in strawberry achenes and receptacles.
• The identified protein conjugates suggest a role for chaperonins or ATP synthases in IAA metabolism or transport during fruit development.
• Further research is warranted to elucidate the precise function of these IAA-modified proteins in strawberry fruit physiology.