Abstract
BackgroundStarch from maize kernels has diverse applications in human and animal diets and in industry and manufacturing. To meet the demands of these applications, starch quantity and quality need improvement, which requires a clear understanding of the functional mechanisms involved in starch biosynthesis and accumulation. In this study, a recombinant inbred line (RIL) population was developed from a cross between inbred lines CI7 and K22. The RIL population, along with both parents, was grown in three environments, and then genotyped using the MaizeSNP50 BeadChip and phenotyped to dissect the genetic architecture of starch content in maize kernels.ResultsBased on the genetic linkage map constructed using 2,386 bins as markers, six quantitative trait loci (QTLs) for starch content in maize kernels were detected in the CI7/K22 RIL population. Each QTL accounted for 4.7 % (qSTA9-1) to 10.6 % (qSTA4-1) of the starch variation. The QTL interval was further reduced using the bin-map method, with the physical distance of a single bin at the QTL peak ranging from 81.7 kb to 2.2 Mb. Based on the functional annotations and prior knowledge of the genes in the top bin, seven genes were considered as potential candidate genes for the identified QTLs. Three of the genes encode enzymes in non-starch metabolism but may indirectly affect starch biosynthesis, and four genes may act as regulators of starch biosynthesis.ConclusionsA few large-effect QTLs, together with a certain number of minor-effect QTLs, mainly contribute to the genetic architecture of kernel starch content in our maize biparental linkage population. All of the identified QTLs, especially the large-effect QTL, qSTA4-1, with a small QTL interval, will be useful for improving the maize kernel starch content through molecular breeding.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0675-2) contains supplementary material, which is available to authorized users.
Highlights
Starch from maize kernels has diverse applications in human and animal diets and in industry and manufacturing
The Best Linear Unbiased Prediction (BLUP) value of the starch content revealed that the mean of the CI7/K22 recombinant inbred line (RIL) population was close to the mid-parent value (Table 1)
The genetic component of starch content in maize kernels In the CI7/K22 RIL population, Quantitative trait locus (QTL) mapping revealed that the variation in the starch content of maize kernels is controlled by at least six QTLs detected by the BLUP value, each accounting for 4.7–10.6 % of the phenotypic variation
Summary
Starch from maize kernels has diverse applications in human and animal diets and in industry and manufacturing. Maize mutants have been used to isolate genes encoding key enzymes in starch metabolism, such as Shrunken (sh1), Shrunken (sh2), Brittle (bt2), agpsemzm, agpllzm, Waxy (wx1), SS1, Sugary (su2), Dull (du1), SS2b-2, SS2c, SS3b-1, SS3b-2, SS4, SBEIa, SBEIIa, Amylose extender (ae1) and Sugary (su1) [2, 3]. Su encodes a DBE of the isoamylase type, and mutant su kernels contain the highly branched, water-soluble phytoglycogen and constitute the original sweet corns [17]. These are the key steps in maize starch metabolism, but how they are connected still requires clarification. Little is known regarding the regulation of starch biosynthesis and accumulation in maize
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