Table 4_Mapping QTLs for Pyricularia leaf spot, nematode resistance, and yield related traits in pearl millet [Cenchrus americanus (L.) Morrone].xlsx

Pearl millet [Cenchrus americanus (L.) Morrone, formerly Pennisetum glaucum (L.) R. Br.] is the sixth most important cereal globally and is used for forage and feed in the U.S. To identify genomic regions governing important physiological, agronomic and yield related traits, a recombinant inbred line population derived from the cross between Tift 99D2B1 × Tift 454 was phenotyped in the field in 2006, 2007 and 2013. In addition, the population was phenotyped for root-knot nematode resistance in the greenhouse during 2009. Using a previously generated genetic map containing 505 single nucleotide polymorphism markers and composite interval mapping, we identified 45 QTLs for eight traits (plant height, stem diameter, days to heading, panicle diameter, panicle length, 1000 seed weight, Pyricularia leaf spot disease, and root-knot nematode egg mass) across almost all linkage groups. These QTLs explained 6.31 to 32.51% of phenotypic variance for each trait and were consistently detected over different environments. Plant height and days to heading were colocalized on LG2 and LG5 showing maturity and plant height are linked and influence each other, similarly to other cereal crops. Interestingly, 5 of 19 QTLs linked to plant height, stem diameter, panicle diameter, and panicle length colocalized to the same locations on LG3, indicating breeding for one trait could simultaneously improve the other. The markers and genes identified in the present study can be used in developing high yielding pearl millet varieties using marker-assisted selection.

珍珠粟（Pearl millet）的学名是Cenchrus americanus (L.) Morrone，曾用名为Pennisetum glaucum (L.) R. Br.，是全球第六大重要谷类作物，在美国主要用作饲草与饲料。为鉴定调控重要生理、农艺及产量相关性状的基因组区域，本研究针对由Tift 99D2B1与Tift 454杂交获得的重组自交系（recombinant inbred line, RIL）群体，分别于2006年、2007年和2013年开展田间表型鉴定，并于2009年在温室中完成根结线虫抗性的表型检测。研究采用此前已构建的包含505个单核苷酸多态性（single nucleotide polymorphism, SNP）标记的遗传图谱，结合复合区间作图法（composite interval mapping, CIM），在几乎所有连锁群（linkage group, LG）上共鉴定出覆盖8个性状的45个数量性状基因座（quantitative trait locus, QTL），所涉性状包括株高、茎粗、抽穗期、穗直径、穗长、千粒重、梨孢叶斑病及根结线虫卵块。上述QTL对各性状表型变异的解释率介于6.31%至32.51%之间，且在不同环境下均能稳定检出。其中，株高与抽穗期在连锁群LG2和LG5上存在共定位现象，表明成熟期与株高存在连锁关联且相互影响，这一规律与其他谷类作物一致。值得注意的是，与株高、茎粗、穗直径及穗长相关的19个QTL中，有5个在LG3的相同区域发生共定位，这意味着针对单一性状开展育种可同时改良其他相关性状。本研究鉴定得到的标记与基因可应用于通过标记辅助选择（marker-assisted selection, MAS）培育高产珍珠粟品种。