Construction of genetic linkage map and identification of a novel major locus for resistance to pine wood nematode in Japanese black pine (Pinus thunbergii)

Abstract

Background Pine wilt disease (PWD), which is caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus, is currently the greatest threat to pine forests in Europe and East Asian countries including Japan. Constructing a detailed linkage map of DNA markers and identifying PWD resistance genes/loci lead to improved resistance in Pinus thunbergii, as well as other Pinus species that are also susceptible to PWD. Results A total F1 mapping population of 188 individuals derived from a cross between the PWD-resistant P. thunbergii varieties ‘Tanabe 54’ (resistant rank 2 to PWD) and ‘Tosashimizu 63’ (resistant rank 4 to PWD) was inoculated with PWN, and was evaluated for disease symptoms. To perform linkage analysis for PWN resistance, a set of three maps was constructed; two parental maps generated using the integrated two-way pseudo-testcross method, and a consensus map with population-type cross-pollination. The linkage map of ‘Tanabe 54’ consisted of 167 loci, and covered 14 linkage groups (LGs), with a total genetic distance of 1214.6 cM. The linkage map of ‘Tosashimizu 63’ consisted of 252 loci, and covered 14 LGs, with a total genetic distance of 1422.1 cM. The integrated consensus map comprised 12 LGs with the basic chromosome number of P. thunbergii, and a total genetic distance of 1403.6 cM. Results from quantitative trait loci (QTL) analysis using phenotype data and linkage maps indicated that PWN resistance is controlled by a single dominant allele, which was derived from the ‘Tanabe 54’ female parent. This major QTL was located on linkage group 3 and was designated PWD1 for PINE WILT DISEASE 1. Conclusions The PWD1 locus is a major resistance QTL located on the Pinus consensus LG03 that acts in a dominant manner to confer pine wood nematode resistance. Information from the present study will be useful for P. thunbergii breeding programs to improve resistance to PWD, and also to help identify susceptibility genes in Pinus species.

Virulence of seven pathogenicbursaphelenchus xylophilusisolates inpinus pinasterandpinus radiataseedlings and its relation with multiplication

“…Like some studies that support varying virulence levels among populations (Akiba et al, 2012;Kiyohara & Bolla, 1990), the B. xylophilus isolates we tested exhibited different virulence levels, though they were all known to be pathogenic isolates. This was the first time that the virulence level of two Spanish B. xylophilus isolates (SpPO1 and SpSA1) were evaluated in comparison with isolates from other origins, including two Japanese isolates (S10 and Ka4) that are widely used in experiments due to their high virulence (Akiba et al, 2012;Filipiak, 2015;Hirao et al, 2019). It is crucial to know the virulence levels of these isolates, especially that of SpPO1, because the Galician P. pinaster and P. radiata breeding programmes are using it as the test isolate for selecting tolerant genotypes .…”

“…This was the first time that the virulence level of two Spanish B . xylophilus isolates (SpPO1 and SpSA1) were evaluated in comparison with isolates from other origins, including two Japanese isolates (S10 and Ka4) that are widely used in experiments due to their high virulence (Akiba et al, 2012; Filipiak, 2015; Hirao et al, 2019). It is crucial to know the virulence levels of these isolates, especially that of SpPO1, because the Galician P .…”

Optimization of factors affecting the rooting of pine wilt disease resistant Masson pine (Pinus massoniana) stem cuttings

“…This strategy was successfully adopted by Japan; consequently, the survival rate of the progeny of selected Japanese red pine and black pine increased by 18% and 35%, respectively, compared with that of the non-selected population [14]. Moreover, Hirao et al [15] identified a novel PWN resistance locus in black pine. In 2000, the Anhui Forestry Academy launched a breeding project to study PWN resistance of Masson pine in Anhui, China, in cooperation with the government of Japan.…”

Inheritance of the wood properties of the Japanese red pine (Pinus densiflora Siebold et Zucc.) from the open-pollinated families selected as resistance to the pine wood nematode

“…Pine wilt disease is a serious tree disease affecting the genus Pinus that is caused by the pine wood nematode (Bursaphelenchus xylophilus [Steiner and Buhrer] Nickle) (Kiyohara and Tokushige, 1971;Futai and Furuno, 1979;Fujimoto et al, 1989;Toda and Kurinobu, 2002;Toda, 2004;Kuroda et al, 2007;Kurinobu, 2008;Zhao et al, 2008;Ribeiro et al, 2012;Vicente et al, 2012;Carrasquinho et al, 2018;Menéndez-Gutiérrez et al, 2018;Hirao et al, 2019;Iki et al, 2020;Matsunaga et al, 2020). In Japan, the disease mainly occurs in the forestry species P. densiflora Siebold et Zucc.…”