【作者】 曾长英；

【导师】 胡承孝； 徐芳森；

【作者基本信息】 华中农业大学 ， 植物营养学， 2007， 博士

【摘要】 硼是高等植物的必需矿质营养元素，然而，不同植物或同一植物的不同基因型对低硼胁迫的反应存在显著的差异，开展硼营养高效的生理和遗传机制研究将有助于硼高效机理的认识，以及作物硼营养性状的遗传改良。本文在对含97个株系的拟南芥重组自交系群体的硼效率系数进行初步定位的基础上，针对硼高效QTLAtBE1-2位点开展硼高效的生理基础，QTL精细定位及其低硼胁迫下的基因表达等方面的研究，主要获得了以下主要结果：1．硼高效QTL的定位1．1对拟南芥重组自交系群体硼效率的表型数据和分子标记数据进行优化处理后，用不同的QTL分析软件对同一套数据进行对比分析，确保QTL定位结果的准确性。对重组自交系群体的3个性状（低硼条件下籽粒产量-SYLB，正常硼条件下籽粒产量-SYHB和硼效率系数硼-BEC）进行相关性分析、QTL定位、上位性分析以及条件QTL分析后，发现SYLB和BEC之间存在紧密的遗传连锁关系，SYHB则相对独立。1．2根据初步定位的4个硼高效QTL位点，对重组自交系群体各株系的遗传背景和硼效率系数进行选择，获得在QTL AtBE1-2区域内标记的基因型存在差异，其它3个QTLs区域内标记的基因型相同，同时硼效率显著差异的两个株系：硼高效株系1938和硼低效株系1961。利用1961和1938这2个株系作为亲本构建F₂分离群体，在目标QTL AtBE1-2位点检测到控制低硼条件下籽粒产量的一个QTL，从而证实硼高效QTL AtBE1-2位点的可靠性。1．3用目标QTL AtBE1-2峰值附近的两个SSLP标记ATPASE和nga692在1200个F₂单株中筛选出54个重组单株，对其中的26个不同类型重组单株的F_2：3家系的SYLB，SYHB，BEC进行考察，结果显示，目标QTL AtBE1-2显著影响重组单株的F_2：3家系的BEC，进一步证实了该QTL的表型效应。2．目标OTL AtBE1-2的生理功能比较重组自交系群体的亲本（Ler和Col-4）和F₂分离群体的亲本（1938和1961）在5个低硼胁迫浓度和3个生长发育时期不同组织部位的硼浓度，硼累积量等性状的差异，及其与硼高效QTLs关系，推测目标QTL AtBE1-2的主要功能是促进硼的高效利用。3．硼高效候选基因的确定分析1938与Col-4在长期和短期低硼胁迫处理下的基因表达谱，并结合差异表达基因在染色体上的位置，发现36个基因在基因型之间和受低硼诱导显著差异表达，且位于目标QTL区域内。其中16个基因与长期胁迫处理下基因型间4倍以上差异表达基因，或各自材料低硼胁迫处理下4倍以上差异表达基因相重叠，成为目标QTLAtBE1-2的候选基因。更多还原

【Abstract】 Boron （B） is an essential micronutrient for higher plants, but the adaptability of plants to B deficiency varied widely between and within species. The studies on physiological and genetic mechanisms of B will benefit the understanding of B efficiency and genetic improvement of B nutrition trait in crops. Based on primary quantitative trait loci （QTL） analysis of B efficiency coefficient （BEC） in a Arabidopsis thaliana Ler×Col recombinant inbred line （RIL） population containing 97 lines, this study focused on the QTL mapping, and physiological function and gene differential expression under B deprivation aiming at the target QTL AtBE1-2, and the main results were shown as following:1. QTL Mapping for B efficiency1.1 By properly optimizing the phenotypic data and molecular markers data in the RIL population, the QTL analysis for B efficiency was conducted by using 3 different QTL mapping softwares, and then final QTLs loci of B efficiency were determined. Based on the correlation analysis, unconditional QTL mapping, conditional QTL mapping and epistatic interactions analysis among 3 traits （seed yield under low B condition-SYLB, seed yield under high B condition-SYHB and B efficiency coefficient-BEC） of RIL population, the results showed that there was a tightly genetic linkage relationship between SYLB and BEC, while SYHB was independent on SYLB and BEC.1.2 Based on the information of 4 QTLs for BEC detected in the RIL population, genotypic and BEC phenotypic selections were conducted for the each RIL line. 1938 （a B-efficient line） and 1961 （a B-inefficient line） were chosen out, which showed the genotype difference in the target region of AtBE1-2, identical genetic makeup in the region of the other three QTLs whilst their largest difference in BEC among the 97 RILs. With a F₂ segregation population derived from a cross between the two lines, a QTL controlling seed yield under low B was founded to co-locate at the region of AtBE1-2, it confirmed the authenticity of the target QTL AtBEl-2 for B efficiency.1.3 54 recombinants were screened from 1200 individuals in a F₂ population by two flanking markers （ATPASE and nga692） of target QTL AtBE1-2. And then SYLB, SYHB and BEC were investigated in 26 F_2:3 families derived from 26 out of 54 recombinants, results showed that the target QTL AtBE1-2 had significantly influence on the value of BEC. It validated the phenotypic effect of target QTL AtBE1-2.2. Physiological mechanism of QTL AtBE1-2 for B efficiencyAnalyzing the differences in B-related traits （B concentration, B accumulation） among four lines, her and Col-4 （parents of the RIL population）, 1938 and 1961（parents of the F₂ population） at 3 developmental stages under 5 B levels, and compared with the differences with the corresponding QTLs possessed in each genotype, we deduced that the main function of QTL AtBEl-2 is to enhance the utilization of B in the silique when plants sufferred from B deficiency.3. Candidate genes at the region of B efficiency QTL AtBE1-2Based on gene expression profiles of 1938 and Col-4 in short-and long-term B deprivation, together with the chromosome position of differential expressed genes, 36 significantly differential expression genes were located in the target QTL AtBE1-2 region. 16 of them showing 4-fold changes between the two genotypes or in any one genotype under low B deprivatioin were considered as candidate gene of QTL AtBE1-2. It laid a fine foundation for next gene cloning and function validation.更多还原