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首页> 外文学位 >Unexploited germplasm, natural mutations, and selected in vitro techniques for Citrus cultivar improvement.
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Unexploited germplasm, natural mutations, and selected in vitro techniques for Citrus cultivar improvement.

机译：未开发的种质，自然突变和用于柑橘栽培品种改良的体外技术。

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摘要

Breeding of Citrus by sexual hybridization has not been an effective strategy for cultivar improvement because of long juvenile stages and widespread apomixis. Investigations of unexploited genetic resources or systems of evaluation may identify methods to increase the rate of genetic advance. One potential germplasm resource, two sources of genetic mutants, and one novel method of in vitro evaluation for disease resistance were examined during this study. The potential value of each project was critically reviewed.; A diverse population of Citrus, known as forbidden fruit, was discovered in Saint Lucia. Historical records, morphological characteristics, and isozyme evidence indicated that this population was closely related to grapefruit. High degrees of zygotic embryony and diversity within the population may make it a useful source of breeding parents.; Significant morphological variation was observed during initial growth among Citrus plants regenerated from callus cultures by organogenesis. Many of the aberrant plants were indistinguishable from controls after a second cycle of vegetative regrowth. The frequency of genetic mutation that could be measured as stable morphological change in young plants was too low to allow efficient mutant recovery.; Fruit sector chimeras were observed among eight Citrus cultivars at a frequency of 0.01 to 0.27 percent in commercial packinghouses. Mutants were recovered from some sectored fruit as autotetraploid seedlings. Several kinds of sectors with potential value as sources of genetic mutations were described.; In vitro response of etiolated seedling shoots to Phytophthora parasitica was measured as stem discoloration. The non-host, or hypersensitive, response observed in Poncirus trifoliata and Severinia buxifolia was clearly distinguished from the susceptible reaction of eight Citrus selections and hybrids. However, two Citrus x Poncirus hybrids with useful levels of field resistance to this pathogen exhibited a highly susceptible reaction in vitro. This technique may prove useful in the study of resistance mechanisms, but probably will not be effective for population screening.
机译：由于幼年期长和无融合生殖的广泛性，通过有性杂交育种柑橘并不是一种有效的改良品种的策略。对未开发的遗传资源或评估系统的调查可能会确定提高遗传进展速度的方法。在这项研究中，检查了一种潜在的种质资源，两种遗传突变体来源和一种新颖的体外抗病性评估方法。每个项目的潜在价值都经过严格审查。在圣卢西亚发现了各种各样的柑橘，被称为禁果。历史记录，形态特征和同工酶证据表明该种群与葡萄柚密切相关。群体中高度的合子胚和多样性可能使其成为育种父母的有用来源。在通过器官发生从愈伤组织培养物再生的柑橘植物之间的初始生长期间观察到显着的形态变化。在第二个营养再生周期后，许多异常植物与对照没有区别。可以测量为幼苗中形态稳定的遗传突变的频率太低，无法有效地恢复突变体。在商业包装厂中，在八个柑橘品种中观察到果实扇形嵌合体，频率为0.01％至0.27％。从某些扇形果实中回收了突变体，成为同源四倍体幼苗。描述了具有潜在价值作为遗传突变来源的几种部门。测定黄化苗芽对寄生疫霉的体外反应，作为茎变色。明显地，在三叶红枣和布氏雪松中观察到的非寄主或超敏反应与八种柑橘和杂种的易感反应区分开。但是，两个对这种病原体具有有用水平抗性的柑橘x庞氏杂种在体外表现出高度敏感的反应。这项技术可能在抵抗机制的研究中被证明是有用的，但可能对人群筛选无效。

著录项

  • 作者

    Bowman, Kim Dean.;

  • 作者单位

    University of Florida.;

  • 授予单位 University of Florida.;
  • 学科 Agriculture Agronomy.; Biology Genetics.
  • 学位 Ph.D.
  • 年度 1990
  • 页码 226 p.
  • 总页数 226
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农学（农艺学）;遗传学;
  • 关键词

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