Role of Phytohormones in Soybean (Glycine max) Seed Development

Abstract

Phytohormones play a key important role in the sink development of the seed. Endogenous content of IAA, PAA, GA, ABA, and kinetin were estimated in two distinct varieties of soybean (Glycinemax (L.) Merr.) during the entire period of seed development. Antibodies against IAA, PAA, GA, ABA, and kinetin were raised in rabbits. By competitive ELISA, hormones were estimated from the two different varieties: Large seeded variety (L seed) and Small seeded variety (S seed). Growth analysis showed that L seed had more dry weight, the rate of dry matter accumulation and water content than S seed. Plant hormones are signal molecules that regulate many developmental processes, including sink size and dry matter accumulation in viable mature seed. In both the varieties, the free IAA increased gradually with the seed age; value was near to double in L seed. PAA was also observed higher in L seed than S seed during cell elongation period. While GA content was higher in S seed in compare to IAA and PAA. ABA content was observed 2–4 times lower as compared S seed. A significant difference was observed in kinetin levels which showed nearly 1.5 times higher in L seed compared to S seed. GA and ABA levels were more in S seed suggest that GA/ABA ratio and total hormonal balance determine the sink size. The probable role of hormones in seed development is discussed.