Changes in L-phenylalanine ammonia-lyase activity and isoflavone phytoalexins accumulation in soybean seedlings infected with Sclerotinia sclerotiorum

Abstract

Soybean [Glycine max (L.) Merr.] cultivars (Meli, Alisa, Sava and 1511/99) were grown up to V1 phase (first trifoliate and one node above unifoliate) and then inoculated with Sclerotinia sclerotiorum (Lib.) de Bary under controlled conditions. Changes in L-phenylalanine ammonia-lyase (PAL) activity and isoflavone phytoalexins were recorded 12, 24, 48 and 72 h after the inoculation. Results showed an increase in PAL activity in all four examined soybean cultivars 48 h after the inoculation, being the highest in Alisa (2-fold higher). Different contents of total daidzein, genistein, glycitein and coumestrol were detected in all samples. Alisa and Sava increased their total isoflavone content (33.9% and 6.2% higher than control, respectively) as well as 1511/99, although 48 h after the inoculation its content decreased significantly. Meli exhibited the highest rate of coumestrol biosynthesis (72 h after the inoculation) and PAL activity (48 h after the inoculation). All investigated cultivars are invariably susceptible to this pathogen. Recorded changes could point to possible differences in mechanisms of tolerance among them.

In vitro lipid-lowering properties of the fruits of two bignay [Antidesma bunius (L.) Spreng] cultivars as affected by maturity stage and thermal processing

“…Polyphenols, having at least one aromatic ring with one or more hydroxyl groups, are secondary metabolites widely distributed in all plants synthesized during normal plant development as well as in response to stress conditions such as ultraviolet radiation, infections, bruising, etc. ( Beckman, 2000 , Malenčićet al, 2013 ). However, variety of factors, such as environmental condition, genotype, cultivar, harvest time, storage condition, and processing could affect the levels of polyphenols in foods and plants.…”