|
Little is known about the regulation of IAA level in plants under low temperature. On exposing 6-day-old etiolated pea(Pisum, sativum L, var. Sparkle) seedlings grown at 25 ℃ to 5 ℃ for 3 days, free IAA level decreased from 17.6 to 4.9 ng/g fresh weight(that is, from 68 to 10 p㏖/shoot) and total IAA level from 113.2 to 60.8ng/g FW. The level of free tryptophan, precusor of IAA, also decreased from 583 to 414 n㏖/g FW and that of free phenylalanine and tyrosine, products of shikimic acid pathway along with tryptophan, decreased from 3,168 to 2,327 n㏖/g FW. Thus low temperature was found to down-regulate the level of endogenous IAA, in part, by reducing tryptophan biosynthesis in etiolated pea shoots.
|