Phytochrome chromophore biosynthesis. Both 5-aminolevulinic acid and biliverdin overcome inhibition by gabaculine in etiolated Avena sativa L. seedlings

• Published in: Plant physiology (Bethesda) Vol. 84; no. 2; pp. 304 - 310
• Main Authors: Elich, Tedd D., Lagarias, J. Clark
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-06-1987
• Subjects: acide organique; acidos organicos; Agronomy. Soil science and plant productions; ahilamiento; amino compounds; Antiserum; Apoproteins; avena sativa; bile; bilis; Biological and medical sciences; biosintesis; biosynthese; Biosynthesis; Chromium; Chromophores; compose amine; compuestos de amina; Economic plant physiology; etiolation; etiolement; Fundamental and applied biological sciences. Psychology; Gels; immunological techniques; Kinetics; Metabolism; Nutrition. Photosynthesis. Respiration. Metabolism; Oats; organic acids; pigment; pigmentos; pigments; Plant physiology and development; Plants; plantulas; plantule; Reserves and secretions. Pigments. Phytochromes; Seedlings; Storage and secretion, pigments, phytochrome; technique immunologique; tecnicas inmunologicas; Avena sativa; Monocotyledones; Gramineae; Apoproteins; Angiospermae; Phytochrome; Spermatophyta; Biosynthesis; Metabolic inhibitor; Cereal crop; Chromophore
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.84.2.304

Etiolated Avena sativa L. seedlings grown in the presence of gabaculine (5-amino-1,3-cyclohexadienylcarboxylic acid) contained reduced levels of phytochrome as shown by spectrophotometric and immunochemical assays. Photochromic phytochrome levels in gabaculine-grown plants were estimated to be 20% of control plants, while immunoblot analysis showed that the phytochrome protein moiety was present at approximately 50% of control levels. Gabaculine-grown seedlings administered either 5-aminolevulinic acid or biliverdin exhibited a rapid increase of spectrophotometrically detectable phytochrome. Phytochrome concentrations estimated immunochemically did not similarly increase throughout treatment with either compound. Similar experiments with 5-amino[4-14C]levulinic acid showed radiolabeling of phytochrome with kinetics that paralleled the spectrally detected increase. These results are consistent with (a) the intermediacy of both 5-aminolevulinic acid and biliverdin in the biosynthetic pathway of the phytochrome chromophore and (b) the lack of coordinate regulation of chromophore and apoprotein synthesis in Avena seedlings.