Lipoxygense Activity and C6‐Aldehyde Formation in Comparison to Germination and Vigor during Soybean Seed Development

Abstract

Developmental changes in lipoxygenase (LOX) activity have been observed during embryo maturation, which suggests that the LOX pathway may be involved in seed development. A study was designed to measure changes in LOX activity and C6‐aldehyde (hexanal and hexenal) formation during seed development and relate these changes to the attainment of maximum germination and vigor. Field grown soybean [Glycine max L. (Merr.) cv. Century] seeds were sampled at regular intervals starting at 31 d after flowering and continuing until maximum dry seed weight [physiological maturity (PM)] in 1990 and 1991. Axes and cotyledons from freshly harvested seeds were evaluated for LOX activity and C6‐aldehyde formation. The remaining seeds were air dried and tested for germination and vigor. Maximum germination occurred at 46 and 43 d after flowering in 1990 and 1991, respectively. Maximum vigor, as measured by accelerated aging, occurred at 54 and 48 d after flowering in 1990 and 1991, respectively, which was 18 d before PM. During seed development, maximum LOX activity occurred in both the axes and cotyledons during the linear phase of seed growth, but declined before PM. In the axes and cotyledons, maximum hexanal and trans‐2‐hexenal formation occurred at approximately 30% of final dry weight, which was before maximum LOX activity, except for axes in 1990. Maximum hexenal and hexenal formation coincided with the first maximum expression of germination, while maximum vigor was more closely related to maximum LOX activity in the axes (1991) and cotyledons. Maximum expression of seed quality (germination and vigor) and maximum LOX and C6‐aldehyde formation were correlated during soybean seed development.