The outermost cuticle of soybean seeds: chemical composition and function during imbibition

Seeds of different cultivars of Glycine max (L.) Merr. (soybean) have strikingly different rates of water imbibition. Seeds that readily imbibe water are termed 'soft', while those that remain non-permeable, even after several days in water, are referred to as 'hard', 'stone', or 'impermeable' seeds. What prevents soybean hard seeds from taking up water? Previous work established that the initial imbibition of soft soybean seeds correlates with the presence of small cracks in the outermost cuticle that covers the seed coat, prompting a detailed analysis of soybean seed coat cutin. In this paper, it is shown that the outermost cuticle of the seed coat has an unusual chemical composition, lacking typical mid-chain-hydroxylated fatty acids but being relatively rich in other types of hydroxylated fatty acids. The cuticle of the impermeable cultivar studied contained a disproportionately high amount of hydroxylated fatty acids relative to that of the permeable ones. Moreover, a brief treatment with hot alkali released the omega-hydroxy fatty acid component of the outermost cuticle and created holes in it that caused the seeds to become permeable. This demonstrates that the outermost cuticle of the seed is the critical structure that prevents water uptake by hard seeds.     

The chemical composition of Microbiota decussata

From the leaves of Microbiota decussata (Cupressaceae) biflavones: cupressuflavone, amentoflavone and 7-O-methylamentoflavone were isolated and identified. The amount of cupressuflavone in Microbiota decussata and xCupressocyparis leylandii (Leyland cypress) (Cupressaceae) was determined by HPLC (1.82% and 0.83%, respectively). The chemical composition of essential oils from bark and leaves of Microbiota decussata was established by GC-MS (GC-FID) analysis. As a major component thujopsene (39.2% and 45.9%, respectively) was identified. Wiridiflorol (3.0%) and tau-muurolol (0.3%) were present only in leaves but globulol (1.5%) exclusively in bark. The content of essential oils in M. decussata was high--5.4% in bark and 12.6% in leaves. The essential oils from M. decussata and xC. leylandii were bioassayed towards different fungi of the genus Fusarium. Leyland cypress essential oil at 2% concentration fully inhibited the growth of all fungi.     

The chemical composition of interstellar molecular clouds

Relative abundances for molecules observed by radio astronomical techniques have been determined for several interstellar regions with differing physical properties.