A Comparative Transcriptome Analysis of Avocado Embryogenic Lines Susceptible or Resistant to Rosellinia necatrix Exudate

Abstract

Avocado embryogenic cultures were selected for resistance to the culture filtrate (CF) of Rosellinia necatrix, the causal agent of White Root Rot disease. A resistant callus line was obtained through recurrent selections in progressively increasing concentrations of fungal CF (from 60% to 80%). RNA sequencing (RNA-Seq) technology was used to compare the transcriptomic profiles of the avocado embryogenic-callus-resistant line L3 (capable to survive in the presence of 80% CF) and control line AN-9 (not exposed to CF), after 24 h of growth in a medium containing 40% CF. A total of 25,211 transcripts were obtained, of which 4,918 and 5,716 were differentially expressed in the resistant and control line, respectively. Interestingly, exposure of embryogenic callus lines to 40% of R. necatrix exudates induced genes previously reported to be related to avocado defense against fungal diseases (lignin biosynthesis, Pathogenesis Related (PR) proteins, WRKY (WRKYGQK) Transcription Factor (TF), NAC (NAM, ATAF1/2, and CUC2) TF, proteinase inhibitors and Ethylene Response Transcription Factor (ERF), among others), which were accumulated in greater amounts in the resistant line in comparison to the susceptible one. This research will contribute to the understanding of avocado defense against this pathogen, thereby aiding in the selection of resistant avocado rootstocks.

Global Transcriptome Analysis of the Peach (Prunus persica) in the Interaction System of Fruit–Chitosan–Monilinia fructicola

“…For example, many members of the WRKY ( WRKY29 , WRKY33 , WRKY45 , WRKY53 ) and NAC gene families were highly induced mainly at 48 HAI, indicating their pivotal role as major positive regulators of the defense responses against necrotrophic fungi [ 57 ]. On the other hand, high levels of upregulation mainly at 48 HAI of AP2 / ERF genes, which are responsive genes in the ethylene biosynthesis and signaling pathway, indicates their role as susceptibility factors to M. fructicola challenge, as was recently reported for different plant–pathogen interaction systems [ 58 , 59 ]. Manipulation of the plant’s HR is a key pathogenicity strategy that necrotrophic fungi have developed [ 60 ].…”

Effects of exogenous application of methyl jasmonate and salicylic acid on the physiological and molecular response of ‘Dusa®’ avocado to Rosellinia necatrix

“…MeJA treatment signi cantly upregulated glu protease inhibitor. This gene encodes proteins linked to different aspects of plant defense such as oxidative stress [78], which may encompass an enhanced ability of plants to withstand R. necatrix infection, consistently with its important role in avocado tolerance to this pathogen [35,79]. Similarly, the enhanced expression of endochitinases, PR4 and PR5 induced by MeJA could also represent a bene t to overcome WRR disease [28].…”

“…Overall, the overexpression of the above-mentioned genes [80, 81], has been described in the response of tolerant avocado plant material to P. cinnamomi and R. necatrix [34,35,79,82], as well as in susceptible rootstocks after priming with mild water stress [28]. The common overexpression of these genes under diverse stress conditions points to their involvement in a broad range of plant responses to biotic [83,84] and abiotic stress [85,86].…”

Priming avocado with sodium hydrosulfide prior to frost conditions induces the expression of genes involved in protection and stress responses

“…Induction of avocado genes predicted to encode chitinase enzymes has been identified in avocado roots exposed to the fungus-like oomycete Phytophthora cinnamomi (van den Berg et al, 2018), and in roots subjected to several days of flooding (Reeksting et al, 2014). In addition, a chitinase gene, as well as genes predicted to encode thaumatin-like proteins, were found to be up-regulated in avocado embryonic cultures exposed to the fungus Rosellinia necatrix (Moreno-Pérez et al, 2023). Chitinases are also involved in the response to cold [e.g.…”