ER Microsome Preparation and Subsequent IAA Quantification in Maize Coleoptile and Primary Root Tissue

Area of Science:

• Plant Biology
• Molecular Biology
• Biochemistry

Background:

• Auxin, a crucial plant growth hormone, has complex biosynthesis pathways.
• Previous research identified YUCCA-route enzymes in the endoplasmic reticulum (ER) in Arabidopsis and maize.
• This suggests potential subcellular compartmentation of auxin biosynthesis.

Purpose of the Study:

• To investigate the subcellular localization of auxin biosynthesis in maize.
• To demonstrate that maize auxin biosynthesis can occur in both microsomal and cytosolic fractions.

Main Methods:

• Microsomal and cytosolic fractions were isolated from maize coleoptile and primary root tissues.
• Enzyme assays were performed using tryptophan (Trp) or indole-3-pyruvic acid (IPyA) as substrates.
• Auxin indole-3-acetic acid (IAA) was extracted and quantified from the fractions.

Main Results:

• Enzymes involved in the YUCCA-route of auxin biosynthesis were found in both microsomal and cytosolic fractions of maize seedlings.
• This confirms the possibility of subcellular compartmentation for auxin biosynthesis in maize.

Conclusions:

• Auxin biosynthesis in maize seedlings is not restricted to the cytosol.
• The endoplasmic reticulum and other microsomal fractions play a role in auxin production, indicating compartmentation of this vital process.