Open AccessHormone-Mediated Regulative Action of the Sunflower Shoot Apex on Growth and Cation Level in the Cotyledons
Author(s) -
Y. Saks,
I. Ilan
Publication year - 1984
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.74.2.408
Subject(s) - apex (geometry) , auxin , helianthus annuus , biology , botany , kinetin , shoot , apical dominance , sunflower , cotyledon , helianthus , etiolation , tissue culture , horticulture , biochemistry , enzyme , in vitro , gene
Decapitation of the shoot apex of seedlings of Helianthus annuus Lin. above the cotyledonary node brought about promotion of growth in the cotyledons. Potassium level in the cotyledons of decapitated plants was higher, and that of sodium lower, than in those of intact plants. IAA applied to the cut stem surface imitated the effects of the apex. Application of kinetin to the cotyledons antagonized the apex or the auxin in their influence on growth and cation level. Labeled IAA applied to the cut stem surface penetrated into the cotyledons in significant amounts. It was concluded that growth and monovalent cation level in the cotyledons are regulated by auxin released from the shoot apex and that at least part of the auxin effect is exerted directly in the cotyledons. A function of the apex as a sink for cytokinins may also be involved in the control mechanism.