Natural Inhibitors of Germination and Growth IV Compounds from Fruit and Seeds of Mountain Ash (Sorbus aucuparia)

Abstract

Extracts from ripe fruit and seeds of Sorbus aucuparia inhibit germination of other seeds, tested with Amaranthus caudatus and Lepidium sativum. The main compound of the “neutral fraction” of fruit extracts is the lactone compound parasorbic acid (4 -7 mg/g fresh weight) which inhibits germination at concentrations ≧ 5 × 10-4 ᴍ. The “acid fraction” contains abscisic acid (1.3-2.5 µg/g fresh weight) and isopropylmalic acid (1.0-1.5 µg/g fresh weight) as germination inhibitors. Whereas abscisic acid inhibits germination of L. sativum at concentration ≧ 5 × 10-7 ᴍ, germination of A. caudatus is inhibited only at concentrations ≧ 10-5 ᴍ. This is probably due to differences in uptake of the acid because abscisic acid methylester inhibits germination of both species at concentrations ≧ 5 × 10-7 ᴍ. Isopropylmalic acid belongs to a structural type of germination inhibitors which had already been detected in oat extracts.

Effect of electrostatic field on seed germination and seedling growth of Sorbus pohuashanesis

“…The limited propagation experience indicates that the seed rate of S. pohuashanensis fruits is only 1%(w/w) and the seed germination percentage is only about 10%. Like other mountain ash species described by Taylor and Gerrie (1987), Oster et al (1987), Yagihashi et al (1998) and Paulsen et al (2002), S. pohuashanensis seeds could only germinated when the fruits were predated by birds or other animals under natural conditions or cold stratification for 2-4 months or more in nursery production (Zhou 1986). Even if the seeds are treated, the germination percentage is far away from desired.…”

New pathway to polyketides in plants

“…The glucoside is a major cause of the bitter taste of mountain ash berries 12 and acts to prevent yellow butter¯y larvae from feeding 10 . Parasorboside is the precursor of parasorbic acid 11 , which inhibits the growth of fungi 13 and bacteria 14 ; it also delays the germination of seeds 15 and potato tubers 16 . Studies of the pathogen susceptibility of anti-gchs2 lines indicate that gerberin, parasorboside or their derivatives may also protect Gerbera from fungal pathogens and attack by insects (P.E., S. Remes and T.H.T., unpublished data).…”

Dormancy-Breaking and Germination Requirements for Seeds of Sorbus alnifolia (Siebold & Zucc.) K.Koch (Rosaceae), a Mesic Forest Tree with High Ornamental Potential

“…The results of the viability test of S. alnifolia seeds also showed that the viability of freshly matured S. alnifolia seeds was 87.65 ± 11.67%, but this declined to 38.25% after 6-months of storage at room temperature. (2) Flesh seeds of Sorbus species were reported to contain substances that inhibit seed germination [16,43]. Without passing through a bird's digestive tract, few seeds could be germinated in S. pohuashanensis [39], and seedlings of S. aucuparia that grew from ingested seeds appeared first and grew faster than seeds that had not been ingested [14].…”

“…Most seeds of S. commixta and S. aucuparia cannot germinate without being first ingested by birds [14,15]. Oster et al [16] examined the germination inhibitors within the fruits and seeds of S. aucuparia, finding three distinct inhibitors, including parasorbic, abscisic, isopropyl-malic acids. Although germination characteristics have been extensively studied in a number of closely related species [17], seeds of S. alnifolia are associated with dismal and fruitless germination attempts at plant nurseries, which may be related to inadequate artificial preconditioning of seed to break dormancy prior to sowing.…”