title: Branching Mutant rms-2 in Pisum sativum (Grafting Studies and Endogenous Indole-3-Acetic Acid Levels).
abstract: Isogenic lines of pea (Pisum sativum L.) were used to determine the physiological site of action of the Rms-2 gene, which maintains apical dominance, and its effect on endogenous free indole-3-acetic acid (IAA) levels. In mutant rms-2 scions, which normally produce lateral branches below node 3 and above node 7, apical dominance was almost fully restored by grafting to Rms-2 (wild-type) stocks. In the reciprocal grafts, rms-2 stocks did not promote branching in wild-type shoots. Together, these results suggest that the Rms-2 gene inhibits branching in the shoot of pea by controlling the synthesis of a translocatable (hormone-like) substance that is produced in the roots and/or cotyledons and in the shoot. At all stages, including the stage at which aerial lateral buds commence outgrowth, the level of IAA in rms-2 shoots was elevated (up to 5-fold) in comparison with that in wild-type shoots. The internode length of rms-2 plants was 40% less than in wild-type plants, and the mutant plants allocated significantly more dry weight to the shoot than to the root in comparison with wild-type plants. Grafting to wild-type stocks did not normalize IAA levels or internode length in rms-2 scions, even though it inhibited branching, suggesting that the involvement of Rms-2 in the control of IAA level and internode length may be confined to processes in the shoot.
authors.affiliation: Depertment of Plant Science, University of Tasmania, GPO Box 252C, Hobart, Tasmania 7001, Australia.
authors.forename: C. A.
authors.initials: CA
authors.lastname: Beveridge
authors.forename: J. J.
authors.initials: JJ
authors.lastname: Ross
authors.forename: I. C.
authors.initials: IC
authors.lastname: Murfet