Light interacts with auxin during leaf elongation and leaf angle development in young corn seedlings

• Published in: Planta Vol. 216; no. 3; pp. 366 - 376
• Main Authors: Fellner, Martin, Horton, Lindsey A., Cocke, Allison E., Stephens, Nicholas R., Ford, E. David, Van Volkenburgh, Elizabeth
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01.01.2003; Springer; Springer Nature B.V
• Subjects: Adaptation, Physiological - drug effects; Adaptation, Physiological - radiation effects; Agronomy. Soil science and plant productions; Auxins; Biological and medical sciences; Biological Transport - drug effects; Biological Transport - physiology; Biological Transport - radiation effects; Coleoptiles; Corn; Crop yield; Darkness; Declination; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Genotypes; Growth and development; Growth regulators; Humans; Hybrids; Indoleacetic Acids - metabolism; Indoleacetic Acids - pharmacology; Leaves; Light; Mesocotyls; Metabolism; Naphthaleneacetic Acids - pharmacology; Phthalimides - pharmacology; Plant growth; Plant Growth Regulators - pharmacology; Plant Leaves - drug effects; Plant Leaves - growth & development; Plant Leaves - radiation effects; Plant physiology and development; Plants; Seedlings; Space life sciences; Vegetables; Zea mays - drug effects; Zea mays - growth & development; Zea mays - radiation effects; Monocotyledones; Auxin; Growth; Plant juvenile growth stage; Biological transport; Cereal crop; Polar auxin transport; Light interception; Gramineae; Light; Angiospermae; Plant growth substance; Mechanism of action; Elongation; Translocation; Light effect; Zea mays; Etiolation; Planting density; Leaf angle; Zea; Spermatophyta; Phytohormone; Position angle; Hormonal receptor
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-002-0881-7

Modern corn (Zea mays L.) varieties have been selected for their ability to maintain productivity in dense plantings. We have tested the possibility that the physiological consequence of the selection of the modern hybrid, 3394, for increased crop yield includes changes in responsiveness to auxin and light. Etiolated seedlings in the modern line are shorter than in an older hybrid, 307, since they produce shorter coleoptile, mesocotyl, and leaves (blade as well as sheath). Etiolated 3394 seedlings, as well as isolated mesocotyl and sheath segments, were less responsive to auxin and an inhibitor of polar auxin transport, N-1-naphthylphthalamic acid (NPA). Reduced response of 3394 to auxin was associated with less reduction of elongation growth by light (white, red, far-red, blue) than in 307, whereas the activity of polar auxin transport (PAT) and its reduction by red or far-red light was similar in both genotypes. NPA reduced PAT in etiolated 3394 seedlings much less than in 307. A characteristic feature of 3394 plants is more erect leaves. In both hybrids, light (white, red, blue) increases leaf declination from the vertical, whereas NPA reduces leaf declination in 307, but not in 3394. Our results support findings that auxin and PAT are involved in elongation growth of corn seedlings, and we show that light interacts with auxin or PAT in regulation of leaf declination. We hypothesize that, relative to 307, more erect leaves in the modern hybrid may be primarily a consequence of a reduced amount of auxin receptor(s) and reduced responsiveness to light in etiolated 3394 plants. The more erect leaves in 3394 may contribute to the tolerance of the modern corn hybrid to dense planting.