玉米持绿相关ＱＴＬ整合图谱构建及一致性ＱＴＬ区域内候选基因发掘

 以玉米高密度遗传连锁图谱ＩＢＭ２２００８Ｎｅｉｇｈｂｏｒｓ为参考图谱，收集来自不同实验中的１７３个玉米持绿相关数量性状位点（ｑｕａｎｔｉｔａｔｉｖｅｔｒａｉｔｌｏｃｕｓ，ＱＴＬ）信息，利用ＢｉｏＭｅｒｃａｔｏｒ２．１软件，构建出玉米持绿相关ＱＴＬ 整合图谱；采用元分析技术，在１，４，５，９号染色体上发掘出５个持绿“一致性”ＱＴＬ 区间。根据“一致性”ＱＴＬ 区间两端标记在玉米物理图谱Ｂ７３ＲｅｆＧｅｎ＿ｖ２上的位置，将“一致性”ＱＴＬ 区间进行物理图谱定位，利用ＰｌａｎｔＧＤＢ（ｈｔｔｐ：／／ｗｗｗ．ｐｌａｎｔｇｄｂ．ｏｒｇ／）在线区段批量下载工具（ｄｏｗｎｌｏａｄｒｅｇｉｏｎｄａｔａ）下载“一致性”区间的１４４５个预测基因序列并进行生物信息学分析，发现预测基因主要参与具体的细胞过程，执行结合功能，催化、转移酶活性和氧化还原酶活性等分子功能。根据“一致性”ＱＴＬ 区间的基因位点名称，在ＮＣＢＩ中下载相关基因序列，与所在“一致性”ＱＴＬ 区 间所有预测基因保守结构域进行比对，在５个“一致性”持绿ＱＴＬ 区间内初步确定８个持绿相关候选基因。利用ＧＲＡＭＥＮＥ 网站（ｈｔｔｐ：／／ｗｗｗ．ｇｒａｍｅｎｅ．ｏｒｇ／）的Ｃｍａｐ功能，将水稻持绿基因狊犵狉（ｓｔａｙｇｒｅｅｎ）转定位于玉米物理图谱Ｂ７３ＲｅｆＧｅｎ＿ｖ２上，找到与其同源的玉米候选基因ＧＲＭＺＭ２Ｇ０９１８３７＿Ｔ０１，其序列与已发表的玉米衰老诱导叶绿体持绿蛋白基因狊犵狉１序列一致。

Construction of integration QTL map and identification of candidate genes for stay-green in maize

Leaf senescence is a character of plant development.Delayed leaf senescence or stay green character has received considerable attention because of its negative impact on photosynthesis and its role in nutrient redistribution within the plant.In the past few decades,a wealth of QTLs(quantitative trait locus) mapping data for stay green and its related traits in maize has been produced using molecular marker approaches.In order to unlock the full potential of the information contained in these independent experiments,173 stay-green and related QTLs in maize were collected from maize genomic database(maize GDB),and were compiled to construct the integration QTL map for stay-green in maize(Zea mays).The high-scale genetic linkage map of maize IBM2 2008 Neighbors was used as reference and the map were constructed with BioMercator 2.1 software based on the method of meta analysis.Five consensus QTL for maize stay green were identified on maize chromosomes 1,4,5 and 9,respectively.After project the consensus QTL region on maize physical map of B73 RefGen_v2,a total of 1 445 candidate genes in the consensus QTL region were discovered and downloaded from Plant GDB(http://www.plantgdb.org/).Meanwhile,according to the results of gene ontology analysis,most candidate genes might take part in the cell development,catalytic process,enzymatic activity and other biological progresses.The sequences of eight stay-green candidate genes were identified by comparatively analyzing the sequences of stay-green gene sequence from other crops.Using a syntonic conservation approach,which is used to comparatively analyze the rice genetic map and maize physical map,one rice gene(sgr) that is coding for the senescence-inducible chloroplast stay-green protein was projected onto the physical map of maize B73RefGen_v2.Therefore,the results suggested that this approach provided an useful tool for identifying QTL conferring stay-green and other candidate genes in maize.