engleski

4-Cl-IAA, a Potent Substitute for Seeds to Promote Pea Pericarp Growth

Deseeding pea (Pisum sativum L.) pericarps arrests pericarp growth and subsequently leads to abscission of the pericarp. Application of either auxins or gibberellins partially reverses the effect of seed removal. 4-Cl-IAA, an endogenous auxin of peas, is uniquely active. One of the consequences of seed removal is suppression of the oxidation of GA_19 to GA_20. Application of 4-Cl-IAA reverses this effect. Much of the work previously done in our laboratory used 4-Cl-IAA at 1 microgram/pericarp. We now have determined that 50 ng of 4-Cl-IAA is a much more appropriate treatment. By following the metabolism of [C^14]-GA_12-aldehyde in deseeded pericarp we observed that treatment with 1 microgram 4-Cl-IAA promotes the formation of a compound that chromatographs on C18 HPLC like [C^14]GA_53. However, treatment of similar pericarp with 50 ng 4-Cl-IAA, which is adequate to stimulate pod growth, has no detectable effect on the formation of the compound that chromatographs like [C^14]-GA_53. 5 ng of 4-Cl-IAA applied to a pericarp-half elicits a significantly positive growth response. Wounding developing pericarp tissue also suppresses the oxidation of GA_19 to GA_20. Treatment with 4-Cl-IAA overcomes the suppressed formation of GA_20. Compared to other halogenated analogues of IAA, 4-Cl-IAA is uniquely active in the promotion of growth of deseeded pericarps.

Pisum sativum; pea; pericarp growth; wounding; auxin; gibberellin; 4-chloroindole-3-acetic acid; GA12-aldehyde; GA19; GA20; GA53

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