关键词: 马尾松, MuPS分型, 松材线虫病抗性, 遗传多样性, 遗传改良

Abstract:

【Objective】 Pine wilt disease caused by pine wood nematode is one of the most deadly forest quarantine diseases in the world. Screening and innovation of resistance genetic resources is an essential basis for breeding for pine wood nematode disease resistance of Pinus massoniana. The remained genetic resources in the severely disease-affected areas in natural distribution of masson pine, may be an important and potential genetic basis for resistant breeding, which is worth further exploration, systematic evaluation, exploring and utilization. The aim of this study was to comprehensively evaluate the genetic resources of masson pine with phenotypical resistance to pine nematode and its potential value in resistance breeding by analyzing the genetic diversity, growth traits and surveil rate of the 110 selected clones.【Method】 All 1 201 primary-selected clones of masson pine were screened by inoculated pine wood nematode, and 110 re-selected clones with pine wood nematode phenotypic resistance were involved in the evaluation of genetic diversity [by random amplified polymorphic DNA markers (RAPD)], and growth performance. From 14 pairs of SCAR markers, two pairs of primers with strong versatility and high polymorphic loci were selected for MuPS (Multiplex PCR of SCAR Markers) amplification and genetic polymorphic loci detection. The potential value of these masson’s pine genetic resources in resistance breeding was evaluated based on the genetic diversity parameters (estimated by Popgene 32 software) of the 79 clones with unique MuPS type, combined with the traits of single-tree volume and survival rate. 【Result】 There were 110 clones (from 81 families out of primary ) survived among the 1 201 primary selected clones (selected from the 251 primary families), after the inoculation with pine wood nematode. And 92 MuPS types were amplified from the 110 cloned by two pairs of primers, and 79 of the 110 clones were accurately identified by a unique MuPS type (71.81%). Based on the each unique MuPS type’s information of the 79 clones, the average number of effective alleles (N_e) at all loci was 1.508 1, the Nei’s gene diversity (H) was 0.302 3, and the Shannon’s diversity index (I) was 0.459 1. The N_e, H, I for the re-selected population was variated from 1.012 8 to 1.998 1, 0.012 6 to 0.499 5, and 0.038 5 to 0.692 7, respectively. There were 83 clones well survived out of the 110 re-selected clones after pine wood nematode inoculation. There were 83 clones well survived out of the 110 re-selected clones,after the pine wood nematode inoculation. The tree height, DBH and tree volume growth was ranged from 4.6 to 10.7 m, 6.7 to 21.7 cm, and 0.012 3 to 0.189 4 m ³, respectively. And the tree volume of the best performed clone (clone Xiu 3-3, 0.189 4 m³) was more than 15-fold over the lowest clone (clone Guang 27-2, 0.012 3 m³). 【Conclusion】 There were 110 clone among the 1 201 primary clones of masson’s pine, showed significant resistance to pine wood nematode disease after manual inoculation in field, which was around 9% of the primary selected clones. A significant variation/differentiation on tree volume growth was also found among the 110 re-selected clones with phenotypic pine resistance to wilt disease, which may indicated that it was possible to improve tree volume growth based on the disease resistance improvement background. It was worth to notice that, a higher genetic diversity was still existed in the reserved populations in this study, even though ninety percentage of the primary selected clones were eliminated through the disease resistance screening in this study. In conclusion, we believe that these precious genetic resources through resistance screening, have obvious potential value in P. massoniana growth and nematode disease resistance breeding.

Key words: Pinus massoniana, MuPS type, pine wilt disease resistance, genetic diversity, genetic improvement