Lesion Diameter In Fruit Research Articles

The effects of different ambient pH on the pathogenicity of Fusarium sulphureum and reactive oxygen species metabolism in F. sulphureum inoculation muskmelon fruits

Fusarium sulphureum is an important plant pathogenic fungus, which can lead to fusarium rot of muskmelon. During fungal infection host plant, environmental pH plays crucial role by secreting acid or base to regulates the arsenals of enzymes which contribute to fungal pathogenicity. In this study, in order to define the acid-alkali property of F. sulphureum and determinate the effect of ambient pH values on reactive oxygen species (ROS) metabolism and pathogenicity during F. sulphureum infection muskmelon fruits. F. sulphureum spore suspension was modified with different pH values buffer solution and then was inoculated muskmelon fruits. The change of pH value in lesion tissue, the pathogenicity, as well as ROS metabolism in inoculated muskmelon fruits were investigated and analyzed. The results indicated that the pH value of lesion tissue increased from 5.92 on 0 day to 9.24 on 7 day after inoculation, the lesion diameter in fruit inoculated with spore suspension at pH 6 was significantly higher than those at pH 3, 5, 7 and 9. Meanwhile, the inoculated fruits with pH 6 spore suspension showed higher NOX activity, O2−. production and H2O2 content, cell membrane permeability, as well as Malondialdehyde （MDA）content. However, the activities of antioxidant enzyme (such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)) and the activities of key enzymes and the contents of non-enzymatic antioxidants involved in ascorbate-glutathione cycle (AsA-GSH) were remarkedly increased in fruits inoculated with spore suspension at pH 3, comparing with pH 5, 6, 7, 9. Based on the present results, F. sulphureum inoculation led to pH increasing of the tissue around the inoculation site, and weak alkaline environment increased the pathogenicity of F. sulphureum infection muskmelon by stimulating ROS metabolism.

Antifungal activity of 1-octen-3-ol against Monilinia fructicola and its ability in enhancing disease resistance of peach fruit

Peach fruit is susceptible to decay caused by Monilinia fructicola infection. Synthetic fungicides are effective for inhibiting this pathogen and rot rate, but more and more attentions to the safety and pollution that chemicals compel us to find other methods to control M. fructicola disease. Natural volatile organic compound was considered as a potential way to reduce pathogen infection. 1-Octen-3-ol, a natural product from plant or fungi, can inhibit several pathogens growth. In this study, it is found that 1-octen-3-ol fumigation not only inhibited development of M. fructicola in vitro but also effectively reduced brown rot caused by the pathogen in vivo. The results showed 37.20, 55.80 and 74.40 μg mL −1 1-octen-3-ol fumigation could inhibit the extension of M. fructicola hyphae and significantly reduce the ergosterol content of mycelium. The results of microscopy, it can be seen that 1-octen-3-ol destroyed the hyphae morphology and cell structure. The spore apoptosis rate and reactive oxygen species (ROS) increased, and the mitochondrial membrane potential (MMP) decreased. Moreover, 55.80 μg mL −1 1-octen-3-ol fumigation could significantly reduce disease incidence and lesion diameter of fruit. Chitinase and β-1,3-glucanase activities were enhanced, and expression of ICS1 , NPR1 , TGA1 , PR1 were up-regulated, as well as down-regulation of AOS , COI1 and MYC2 . These results indicate that 1-octen-3-ol treatment is a promising approach to control brown rot, which is related to the activation of salicylic acid (SA) signal to enhance fruit disease resistance besides direct destruction of pathogen. • Volatile 1-octen-3-ol could inhibit Monilinia fructicola in vitro. • 1-octen-3-ol destroyed the integrity of fungal biofilm and respiratory energy metabolism. • 1-octen-3-ol treatment effectively inhibited brown rot development in peach fruit. • 1-octen-3-ol may induce disease resistance via activation of SA signal pathway of peach fruit.

The mechanism involved in enhancing the biological control efficacy of Rhodotorula mucilaginosa with salicylic acid to postharvest green mold decay of oranges

The main postharvest pathogen of citrus fruit is Penicillium digitatum. The present study looked at the role of Rhodotorula mucilaginosa enhanced with 0.2 mM salicylic acid (SA) on pH, lignin content accumulation and growth dynamics as a resistance mechanism against P. digitatum in orange fruit. Our findings revealed that the increase in lignin content at 20 °C storage temperature resulted in the significant decrease (P ≤ 0.05) in the lesion diameter in fruit treated with R. mucilaginosa enhanced with or without 0.2 mM SA compared to the untreated fruit (control). In addition, the pH values of the fruit treated with R. mucilaginosa enhanced with or without 0.2 mM SA were 4.43 ± 0.07 and 4.15 ± 0.11, respectively, around the infection site compared to the untreated group. Moreover, the in vivo trial showed that the addition of 0.2 mM SA to the antagonist augmented its growth, and subdued substantially the hyphae and spore germination of P. digitatum in vitro. Also, lower levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2) content were observed in fruit treated with the antagonist enhanced with or without 0.2 mM SA compared to the control. The results established that pH, lignin content accumulation and growth of the yeast played a significant role in the control of green mold decay of orange fruit.

Biocontrol activity of Rhodotorula mucilaginosa combined with salicylic acid against Penicillium digitatum infection in oranges

The effectiveness of Rhodotorula mucilaginosa in combination with salicylic acid (SA) was explored for the control of green mold decay of oranges and the mechanisms involved. The results of the study showed that treatments with the diverse concentrations of SA was remarkable in reducing the disease incidence of oranges and that SA at a concentration of 0.2 mM reduced the decay of oranges from 93.06% to 61.12%. At an incubation temperature of 20 °C and RH of 95% the disease incidence and lesion diameter in fruit treated with R. mucilaginosa enhanced with or without SA were significantly reduced compared to that of the control (P < 0.05). Moreover, the growth of the antagonist was enhanced in vivo by the combination of SA (0.2 mM) at both 20 °C and 4 °C, whiles it did not have any influence on the antagonist in vitro. Mycelia growth and spore germination of P. digitatum in orange wounds were found to be significantly inhibited by the combination of R. mucilaginosa and SA (0.2 mM) from the scanned electron micrographs. Postharvest qualities of orange fruit were not impaired by the combination of the antagonist with SA. Additionally, the combination of the antagonist with SA (0.2 mM) led to an upsurge in polypenoloxidase (PPO), peroxidase (POD), phenylalanine ammonia lyase (PAL), catalase (CAT), ascorbate peroxidase (APX) and β-1,3-glucase (GLU) activities. The improved control via SA could be ascribed either to direct effect or induce resistance of this organic chemical. Thus, the proper combination of R. mucilaginosa and SA can offer a vigorous approach to lessen postharvest decay of oranges.