以优良杂交种豫玉22两亲本Z3和87-1为基础构建一套F₈家系的重组自交系群体为研究材料，在正常供氮和低氮两种氮水平下进行田间试验，利用复合区间作图法对玉米穗长、穗行数、行粒数、百粒重和单穗粒数进行QTL定位分析。两种氮水平下共定位到24个玉米穗部性状的QTL位点，其中正常供氮条件下定位到13个QTL，低氮水平下定位到11个QTL，集中分布在第1(8个QTL)、第5(6个QTL)和第8(5个QTL)染色体上。两种氮水平下共位或紧密连锁的QTL位点较少，表明玉米穗部性状在低氮水平下的遗传机制发生很大改变。研究发现，第1染色体umc1122/bnlg1556位点是一个控制低氮水平下玉米单穗粒数的主效QTL，单个QTL可解释19.7%的表型变异，该位点还同时影响低氮水平下玉米穗长、穗行数和百粒重的表型。与前人定位结果比较发现，该位点所在的染色体区域是一个产量及氮效率相关性状的QTL富集区，对此位点附近进行相关分子标记辅助选择，可能会在玉米氮高效分子育种上有所突破。

In this study, an F₈ maize RIL population derived from elite hybrid maize YY22(Z3×87-1) was used to identify the QTLs for ear traits under high(HN) and low nitrogen(LN) applications in the field. QTLs for ear length(EL), row number(RN), kernel number per row(KN), 100-kernel weight (KW) and kernel weight per plant(KWP) were identified by compositing interval mapping. Totally 24 QTLs were detected, 13 QTLs under HN and 11 QTLs under LN condition. These QTLs clustered mainly in chromosome 1(8 QTLs), 5(6 QTLs) and 8(5 QTLs). A few loci were detected under both LN and HN applications for ear traits, suggesting there was a different genetic basis controlling ear traits under LN versus HN condition in maize. A major QTL on chromosome 1(umc1122/bnlg1556) for KWP under LN condition explain 19.7% of the phenotypic variation. This locus also affected EL, KN and KW under LN condition. Comparing those previously reported QTLs in the same chromosome region, we found that umc1122/bnlg1556 was a QTL-rich region for grain yield and N efficiency traits. Marker-assisted selection (MAS) for this region may be promising for breeding N efficient maize cultivars.

国家自然科学基金项目(30600381)、公益性行业科研专项(200803030)