Response of Resistant and Susceptible Bayberry Cultivars to Infection of Twig Blight Pathogen by Histological Observation and Gibberellin Related Genes Expression

Abstract

Bayberry is an important fruit tree native to the subtropical regions of China. However, a systematic twig blight disease caused by Pestalotiopsis versicolor and P. microspora, resulted in the death of the whole tree of bayberry. The main variety Dongkui is highly sensitive to the twig blight disease, but the variety Zaojia is very highly resistant to the disease. Therefore, it is very necessary to clear the difference between resistant and susceptible varieties in response to the fungal infection. In this paper, we investigated the response of resistant and susceptible bayberry cultivars to infection of twig blight pathogen by histological observation and gibberellin signaling pathway-related genes expression. Microscopic observation revealed the difference in the infection process between resistant and susceptible varieties. The results of frozen scanning electron microscopy showed that the Pestalotiopsis conidia were shrunk, the mycelium was shriveled and did not extend into the cells of resistant cultivars, while the conidia were full and the top was extended, the mycelia was normal and continued to extend to the cells of a susceptible cultivar. Indeed, the medulla cells were almost intact in resistant cultivar, but obviously damaged in susceptible cultivar after inoculation of the main fungal pathogen P. versicolor conidia, which is earlier germinated on sterile glass slide than that of a hard plastic slide. The quantitative real-time PCR results showed a significant difference between resistant and susceptible cultivars in the expression of gibberellin signaling pathway-related genes in leaves and stems of bayberry, which is closely related to infection time, the type of genes and varieties. Overall, this study provides a clue for our understanding of the resistance mechanism of bayberry against the twig blight disease.

Effect of Humic Acid on Soil Physical and Chemical Properties, Microbial Community Structure, and Metabolites of Decline Diseased Bayberry

“…For the bacterial communities at the genus level, the contributions of four main variables were shown as below: 28.8% for exchangeable calcium, 25.0% for available phosphorus, 16.5% for available potassium, 13.0% for available nitrogen, and 10.0% for pH. The contribution of organic matter to bacteria (4.2%) was smaller than to fungi (32.6%), which may be because the decline disease was caused by a fungal pathogen, resulting in a greater number of fungi than bacteria in the rhizosphere of diseased bayberry trees [ 32 ].…”

Arbuscular mycorrhizal fungus alleviates anthracnose disease in tea seedlings

“…Additionally, five DEGs related to GAs, which also function in plant defense system ( Bari and Jones, 2009 ), were all positively correlated with the lesion size ( Supplementary Material 4 ). Gibberellin receptor GID1 genes are important for preventing twig blight pathogen in bayberry ( Ren et al., 2021 ), indicating the positive role in reducing damages of the plant pathogens. According to previous reports ( Alvarez, 2000 ; Vergne et al., 2010 ; Lu et al., 2013 ), SA is involved in the resistance induced by biotrophs and hemibotrophs with the occurrence of systematic acquired resistance (SAR), while JA participates in the resistance from necrotrophs and pests by activating the induced systemic resistance (ISR).…”

Interplay between phytohormone signalling pathways in plant defence – other than salicylic acid and jasmonic acid

“…Although, gibberellins are primarily growth hormones, during Pestalotiopsis versicolor infection (Twig blight pathogen) of bayberry there is significant differentiation of gibberellin-responsive genes between resistant and susceptible cultivars [ 91 ] indicating that the regulation of gibberellins is important for resistance. Plants infected with the phloem colonising bacteria Candidatus Liberibacter asiaticus (CLas) show ROS production, including H 2 O 2 , and ROS-producing NADPH oxidases [ 92 ].…”