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Abstract Detail


Hormone Biology

Jin, Qiaojun [1], Hasenstein, Karl [2].

Auxin effects on cell elongation and microtubule organization in Chara.

Auxin plays important roles in multiple aspects of plant growth and development, but its actions in Chara, a close relative of land plants, are poorly understood. We tested the effets of α-naphthylacetic acid (NAA), indole-3-acetic acid (IAA) and an anti-auxin, 4,4,4-trifluoro-3-(indole-3) butyric acid (TFIBA) on internodal elongation and microtubule (MT) responses in Chara. Unlike higher plants, the elongation of Chara internodes did not respond to α-NAA at concentrations of 10 or 0.1 µ M. IAA (10 or 0.1 µ M) inhibited internode elongation. However, the response depended on the number of internodal cells. Thalli with one internodal cell were inhibited by 0.1 µM IAA, and thalli with two internodal cells were inhibited by 10 µM IAA. The root growth promoter TFIBA (100 µM) showed no effect on internodal growth. Interestingly, methanol, which was used as solvent for the tested compounds, promoted internode elongation. Rhizoid elongation and formation in Chara were not affected by IAA or TFIBA. Similar to higher plants, α-NAA depolymerized MTs in developing antheridia in a transient and concentration dependent fashion. After two h of incubation MTs depolymerized; reformation occurred by 5 h. In contrast, IAA (10µM) caused MT depolymerization after three h. MTs reorganized after 4 h. Our results suggest that during evolution from Chara to land plants, the physiological response to auxin was modified. Supported by NASA grant NNA04CK48G.


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1 - University of Louisiana, at Lafayette, Biology, 104 university circle, Lafayette, LA, 70504, USA
2 - University of Louisiana, at Lafayette, Biology

Keywords:
Chara, IAA, NAA, TFIBA.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P35013
Abstract ID:298


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