Regulation of superoxide dismutase isoforms in resistant and susceptible strawberry cultivars subjected to leaf spot disease

Abstract

Macroscopic symptoms were observed in two strawberry cultivars, with the degree of symptom intensity varying depending on the susceptibility of the cultivars, i.e. resistant or susceptible. The symptoms presented as red spots and were observed 30 d following leaf tissue inoculation with the Mycosphaerella fragariae pathogen. A comparison of the superoxide dismutase isoform profiles obtained by gel electrophoresis in all samples extracted from both resistant and susceptible cultivars indicated one constant sharp band, identified as Mn[sbnd]SOD with a molecular mass of 19 kDa. The intensity of this band was higher in all samples derived from the resistant cultivar than in those from the susceptible cultivar. Another superoxide dismutase (SOD) isoform, identified as CuZn[sbnd]SOD with a molecular mass of 16 kDa, was detected in all soluble proteins derived from the resistant cultivar. This isoform was not observed in the susceptible cultivar; however, following an incremental increase in the amount of loaded protein, it was illuminated as a faint band in a sample collected 3 d after inoculation, indicating insufficient production of the CuZn[sbnd]SOD isoform in the susceptible cultivar during an oxidative burst induced by the M. fragaria pathogen. Several bands were also characterized in both cultivars containing Fe and Mn as their co-factors (Fe, Mn[sbnd]SOD). Unlike in the resistant cultivar, where the activity of Fe, Mn[sbnd]SOD isoforms gradually and regularly increased and reached its highest level on the third day after inoculation, the activity of the isoforms changed irregularly over 20 days of study in the susceptible cultivar.     

Antibiotic activity of the pyrenocines

Pyrenocine A, a phytotoxin produced by Pyrenochaeta terrestris (Hansen) Gorenz, Walker and Larson, possesses general antibiotic activity against plants, fungi, and bacteria. Effective doses for 50% inhibition (ED50s) are 4 micrograms/mL for onion seedling elongation; 14, 20, 20, and 25 micrograms/mL for the germination of asexual spores of Fusarium oxysporum f. sp. cepae, Fusarium solani f. sp. pisi, Mucor hiemalis, and Rhizopus stolonifer, respectively. Pyrenocine A also inhibits the linear mycelial growth of both P. terrestris and F. oxysporum with ED50s calculated as 77 and 54 micrograms/mL, respectively. Gram-positive bacteria are more susceptible to pyrenocine A than Gram-negative bacteria. ED50s are estimated as 30, 45, and 200 micrograms/mL for the inhibition of growth of Bacillus subtilis, Staphylococcus aureus, and Escherichia coli, respectively, with Pseudomonas aeruginosa resistant to those concentrations tested. Pyrenocine A acts primarily as a biostatic rather than a biocidal agent with all organisms tested showing some degree of recovery when released from pyrenocine A. Pyrenocines B and C show little antibiotic activity in the bioassays performed.     

Plant-derived VLP: a worthy platform to produce vaccine against SARS-CoV-2

Biotechnology Letters - After its emergence in late 2019 SARS-CoV-2 was declared a pandemic by the World Health Organization on 11 March 2020 and has claimed more than 2.8 million lives. There has...     

Exogenous Melatonin Alleviates Heat‐Induced Oxidative Damage in Strawberry (Fragaria × ananassa Duch. cv. Ventana) Plant

Journal of Plant Growth Regulation - Melatonin is a signaling molecule that is involved in inducing plants? abiotic stress tolerance. To determine the possible effects of the melatonin...     

Superoxide dismutase responses of strawberry cultivars to infection by Mycosphaerella fragariae

In controlled conditions, the effect of leaf infection by Mycosphaerella fragariae on total superoxide dismutase (SOD, EC 1.15.1.1) activity and induction of SOD isozymes was studied in three different strawberry cultivars, i.e. "Joliette" (resistant), "Honeoye" (partially resistant) and "Kent" (susceptible). Infection of the strawberry leaves with M. fragariae resulted in increase in SOD activities in all three cv. Total SOD increased 1d after inoculation in Joliette and Kent, and 2d after inoculation in Honeoye and reached the highest level in all three cv, at the 2nd day after inoculation, then slowly declined afterward. Total SODs in Joliette and Honeoye at the 2nd day after inoculation were 4516 and 4947Ug(-1) FW, respectively, which were significantly higher than that of Kent (3255Ug(-1)FW). Banding pattern of SOD isozymes in all three cv was also affected by infection. Electrophoresis profile of infected cv revealed two newly synthesized isozymes in Joliette and Honeoye, in which one band, i.e. R(f) = 0.53 was observed exclusively in inoculated Joliette and Honeoye. Therefore, it is considered to be associated with leaf spot resistance.     

Understory light and root ginsenosides in forest-grown Panax quinquefolius

The objective of this study was to determine the relationship between light levels in the understory of a broadleaf forest and the content of six ginsenosides (Rg(1), Re, Rb(1), Rc, Rb(2,) and Rd) in 1- and 2-year-old American ginseng (Panax quinquefolius L.) roots. Our results revealed that ginsenoside contents in 1- and 2 year-old roots collected in September were significantly related to direct and total light levels, and duration of sunflecks. At this time, the effect of light levels accounted for up to 48 and 62% of the variation in ginsenoside contents of 1- and 2-year-old American ginseng roots. Also, red (R) and far red (FR) light, and the R:FR ratio significantly affected Rd, Rc, and Rg(1) contents in 2-year-old roots, accounting for up to 40% of the variation in ginsenoside contents.     

Characterization of novel D-hordeins from <Emphasis Type="Italic">Psathyrostachys juncea</Emphasis>

Three genes encoding novel D-hordeins, Ns 1.3, Ns 2.6, and Ns 2.9 were isolated from Psathyrostachys juncea. The Ns 1.3 differed from Ns 2.6 and Ns 2.9 by having a shorter open reading frame (< 1.5 kb versus > 2.5 kb), and was probably not expressed as a normal protein, while the activities for Ns 2.6 and Ns 2.9 were verified by bacterial expression. Though highly similar primary structure to wheat high molecular mass glutenin subunits (HMM-GSs) and barley D-hordeins, Ns 2.6 and Ns 2.9 had more cysteine residues (nine in total) and a larger molecular mass than HMMGSs, and a longer N-terminal length than D-hordeins. Phylogenetic analysis revealed that the Ps. juncea D-hordeins were divided into Ns 1.3 type and Ns 2.6/Ns 2.9 type. Divergence times indicated that Ns 1.3 diverged the earliest from the orthologous Triticeae locus, while Ns 2.6 and Ns 2.9 and the D-hordeins from two Hordeum species diverged nearly at the same time from those loci, and the divergence between the D-hordeins of H. chilense and Ns 2.6/Ns 2.9 was more recent than between the two Hordeum species. The novel Ps. juncea D-hordeins have the potential to be very important for improving the end-use quality of wheat flours because of the presence of extra cysteine residues and longer repetitive domain, in addition they can contribute to the understanding of the evolution of Triticeae prolamins.