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首页> 外文学位 >Genetic Analysis of Forking Defects in Loblolly Pine.
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Genetic Analysis of Forking Defects in Loblolly Pine.

机译：火炬松分叉缺陷的遗传分析。

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摘要

Forking defects, including stem forking and ramicorn branching, are serious stem-quality problems in loblolly pine (Pinus taeda L.). The presence of forked stems and ramicorn branches greatly reduces wood quality, quantity, and the economic value of the wood. Assessing forking traits may enable breeders to successfully breed and deploy non-forked phenotypes in breeding populations. The objectives of this study were to assess the genetic basis of forking in loblolly pine by assessing trees in a large number of full-sib seedling tests throughout the Southeast and in a clonal test in South Carolina.;In the full-sib tests, the percentage of forking averaged 18%, and ranged from 4% to 80% across different test series. The individual-tree heritability was low (0.06), but family-mean heritabilities were moderately high (half-sib=0.76, narrow-sense full-sib=0.59, broad-sense full-sib =0.71), indicating that forking is partially under genetic control at the family level. By using half-sib family selection with a selection differential of 20%, genetic gain could be achieved with 12% to 23% reduction of forking across different regions. A weak unfavorable genetic correlation (0.18) was found between forking and height, suggesting that selection for growth alone will negatively impact forking in loblolly pine. A favorable genetic correlation (0.33) was found between forking and straightness.;In the clonal test, stem forking and ramicorn branching were serious problems in some clones. Forking averaged 17% with clone means ranging from 0% to 73%, and ramicorn branching averaged 24%, with clone means ranging from 3% to 50%. The estimated clone-mean repeatabilities were 0.86 and 0.67 for forking and ramicorn branching, respectively. Unfavorable genetic correlations between growth traits and forking defects were also found in this clonal test, suggesting that selection for either trait alone will negatively affect the genetic response for the other. A moderate positive genetic correlation between stem forking and ramicorn branching indicates that both traits may be partially controlled by the same genes and could be improved simultaneously.;Co-segregation analysis of markers and QTL for forking was conducted using the clonally replicated progeny of the outbred full-sib family from the clonal test. The linkage map was constructed with three types of markers containing various segregation patterns (F2, BC1 and BC2). A linkage map was achieved with18 linkage groups defined by 409 SNP markers. A single-marker analysis of 1257 loci identified 11 and 9 markers that were significantly associated with stem forking and ramicorn branching, respectively. Those SNP markers explained 7% to 10% of the total phenotypic variation for forking defects. By using the interval mapping method, two QTL were identified for forking, and three QTL were identified for ramicorn branching. Two QTL were detected for both traits using multiple traits analysis, suggesting there are pleiotropic effects on both traits. The result from this study further confirmed that there is genetic control for forking defects, and genetic gain can be achieved through family and clonal selection. With the identified QTL influencing forking defects, marker-assisted selection can be considered in decreasing forking defect in the breeding population of loblolly pine.
机译：分叉缺陷，包括茎分叉和ramicorn分支，是火炬松（Pinus taeda L.）中严重的茎质量问题。分叉的茎和拉米科枝的存在大大降低了木材的质量，数量和木材的经济价值。评估分叉性状可能使育种者能够在育种种群中成功育种和部署非分叉表型。这项研究的目的是通过评估东南部和南卡罗来纳州的大量全同胞幼苗试验和南卡罗来纳州的无性系试验中的树木来评估火炬松的分叉的遗传基础。分叉的平均百分比为18％，不同测试系列之间的比例为4％至80％。单个树的遗传力较低（0.06），但家族平均遗传力适度较高（半同胞= 0.76，狭义全同胞= 0.59，广义全同胞= 0.71），表明分叉是部分在家庭层面受到基因控制。通过使用半同胞家庭选择，选择差异为20％，可以在不同地区分叉减少12％至23％的情况下获得遗传增益。在分叉与身高之间发现弱的不利遗传相关性（0.18），这表明仅选择生长会对火炬松的分叉产生负面影响。在分叉度和直度之间发现了良好的遗传相关性（0.33）。在克隆试验中，茎分叉和Ramicorn分支是一些克隆中的严重问题。分叉平均为17％，克隆平均值为0％至73％，而ramicorn分支平均为24％，克隆平均值为3％至50％。估计分叉和ramicorn分支的克隆平均重复性分别为0.86和0.67。在该克隆试验中还发现了生长性状和分叉缺陷之间不利的遗传相关性，这表明仅选择其中一个性状将对另一个性状的遗传反应产生负面影响。茎分叉和raramcorn分支之间的中等正遗传相关性表明这两个性状可能由相同的基因部分控制并且可以同时得到改善。;使用近交种的克隆复制后代进行标记和QTL的共分离分析全同胞家族的克隆试验。连锁图由包含各种分离模式（F2，BC1和BC2）的三种类型的标记构建。连锁图谱由409个SNP标记定义的18个连锁基团获得。对1257个基因座进行的单标记分析确定了11个和9个与茎分叉和ramicorn分支显着相关的标记。这些SNP标记解释了分叉缺陷的总表型变异的7％至10％。通过使用间隔映射方法，确定了两个QTL进行分叉，并确定了3个QTL进行Ramicorn分支。使用多个性状分析，两个性状均检测到两个QTL，表明对两个性状均具有多效性。这项研究的结果进一步证实，可以对分叉缺陷进行遗传控制，并且可以通过家族和克隆选择获得遗传增益。通过确定的影响分叉缺陷的QTL，可以考虑使用标记辅助选择来减少火炬松繁殖种群中的分叉缺陷。

著录项

  • 作者

    Xiong, Jin.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Biology Genetics.;Agriculture Forestry and Wildlife.;Biology Bioinformatics.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 149 p.
  • 总页数 149
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:36:56

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