The transcriptional response to the olive fruit fly (Bactrocera oleae) reveals extended differences between tolerant and susceptible olive (Olea europaea L.) varieties

Abstract

The olive fruit fly Bactrocera oleae (Diptera: Tephritidae) is the most devastating pest of cultivated olive (Olea europaea L.). Intraspecific variation in plant resistance to B. oleae has been described only at phenotypic level. In this work, we used a transcriptomic approach to study the molecular response to the olive fruit fly in two olive cultivars with contrasting level of susceptibility. Using next-generation pyrosequencing, we first generated a catalogue of more than 80,000 sequences expressed in drupes from approximately 700k reads. The assembled sequences were used to develop a microarray layout with over 60,000 olive-specific probes. The differential gene expression analysis between infested (i.e. with II or III instar larvae) and control drupes indicated a significant intraspecific variation between the more tolerant and susceptible cultivar. Around 2500 genes were differentially regulated in infested drupes of the tolerant variety. The GO annotation of the differentially expressed genes implies that the inducible resistance to the olive fruit fly involves a number of biological functions, cellular processes and metabolic pathways, including those with a known role in defence, oxidative stress responses, cellular structure, hormone signalling, and primary and secondary metabolism. The difference in the induced transcriptional changes between the cultivars suggests a strong genetic role in the olive inducible defence, which can ultimately lead to the discovery of factors associated with a higher level of tolerance to B. oleae.

The Application of Trichoderma Strains or Metabolites Alters the Olive Leaf Metabolome and the Expression of Defense-Related Genes

“…The expression of four defense genes associated with different hormonal pathways involved in plant defense (jasmonic acid, salicylic acid, and ethylene) was investigated. The selected genes represent some of the major mediators of plant defense responses to biotic stresses and environmental threats [ 64 , 65 , 66 , 67 ], and included: (i) ET, which encodes for a transcription factor belonging to the family APETALA2/ERF involved in ethylene signaling and the response pathway, in particular in hormonal cross-talk [ 68 , 69 ]; (ii) LOX, encoding for an enzyme that catalyzes the early steps of jasmonic acid (JA) biosynthesis, and influence local and systemic responses against many biotic and abiotic stresses [ 70 ]; (iii) TD, encoding for an ubiquitous disulfide reductase, enzymes that regulate the redox status of target proteins and play an important role in reactive oxygen species (ROS) scavenging during stress responses [ 71 ]; and (iv) PR27, encoding for a PR-protein included in a group of plant proteins induced in response to fungal, bacterial, viral, and viroid infection, and to some chemicals [ 65 , 66 ]. Interestingly, the fungal metabolite HA caused the upregulation of all selected defense genes, while the strains GV41 and KV906 produced a differential modulation of gene expression.…”

Metabolic Insights into the Anion-Anion Antagonism in Sweet Basil: Effects of Different Nitrate/Chloride Ratios in the Nutrient Solution

“…Real-time PCR was carried out in a final volume of 12.5 microl, containing the 6.5 µL of 2× QuantiFast SYBR Green PCR Master Mix (Qiagen), the primer pairs (300 nM) and the cDNA template. Amplifications were performed as reported [61]. Primers and their temperature of annealing are presented in Supplementary Table S1.…”

Role of Fruit Epicuticular Waxes in Preventing Bactrocera oleae (Diptera: Tephritidae) Attachment in Different Cultivars of Olea europaea

“…The research efforts aimed to investigate the interaction between the olive and its key enemy are relatively few compared with the economic impact of B. oleae [17]. In this context, studies clarifying the attachment ability of B. oleae in relation to the different physico-chemical features of the EW in different O. europaea cultivars could contribute to deepen the knowledge about this important insect pest, thus helping to develop control methods alternative to the use of pesticide harmful for human health.…”

“…Larvae feed upon the olive pulp, thus causing losses of up to 80% of the oil value [15]. Although B. oleae is a key pest in the olive crop, some O. europaea cultivars are less susceptible to B. oleae adult females [14][15][16][17]. Based upon the investigations on the susceptibility of different olive cultivars to B. oleae [18][19][20], it was concluded that female attraction toward the different olive cultivars is due to the interaction of several physical (e.g., fruit size, weight, volume, color) and chemical factors.…”