Abstract
There is a concern on how emerging pests and diseases will affect the distribution range and adaptability of their host species, especially due to different conditions derived from climate change and growing globalization. Fusarium circinatum, which causes pitch canker disease in Pinus species, is an exotic pathogen of recent introduction in Spain that threatens its maritime pine (P. pinaster) stands. To predict the impact this disease will have on the species, we examine host resistance traits and their genetic architecture. Resistance phenotyping was done in a clonal provenance/progeny trial, using three-year-old cuttings artificially inoculated with the pathogen and maintained under controlled environmental conditions. A total number of 670 ramets were assessed, distributed in 10 populations, with a total of 47 families, 2 to 5 half-sibs per family, and 3–7 ramets per clone. High genetic variation was found at the three hierarchical levels studied: population, family and clone, being both additive and non-additive effects important. Narrow-sense and broad-sense heritability estimates were relatively high, with respective values of 0.43–0.58 and 0.51–0.8, depending on the resistance traits measured (lesion length, lesion length rate, time to wilting, and survival). These values suggest the species' high capacity of evolutionary response to the F. circinatum pathogen. A population originated in Northern Spain was the most resistant, while another from Morocco was the most susceptible. The total number of plants that did not show lesion development or presented a small lesion (length<30 mm) was 224 out of 670, indicating a high proportion of resistant trees in the offspring within the analyzed populations. We found large differences among populations and considerable genetic variation within populations, which should allow, through natural or artificial selection, the successful adaptation of maritime pine to pitch canker disease.
Highlights
Under global change scenarios, the future of many plant species, and especially their ability to cope, is a subject of great concern
We found large differences among populations and considerable genetic variation within populations, which should allow, through natural or artificial selection, the successful adaptation of maritime pine to pitch canker disease
Reisolation of F. circinatum from the lesion was achieved in all plants selected for it
Summary
The future of many plant species, and especially their ability to cope, is a subject of great concern. An indirect effect of these scenarios of changing climatic conditions and increasingly globalized trade on plant health is an accelerated introduction of new competitive and invasive pathogens and pests [1]. In particular, have grown exponentially in Europe in the last four decades, with introductions mainly from North America, but recently from Asia [9]. Such invasions may affect the dominant tree species in a particular forest ecosystem, reducing its presence and initiating a cascading effect over the ecology [10], function and value of that forest [7, 11]. Notable examples include Ophiosthoma novo-ulmi in Western Europe, which had a devastating impact on mature elm trees (Ulmus minor) in the 1970s [12]; Chalara fraxinea, which has caused extensive ash (Fraxinus excelsior) dieback throughout Europe since the 1990s [13]; and Phytophthora ramorum, a generalist pathogen of recent introduction in Europe and America [14, 15]
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