The foxtail millet exhibits a diverse range of hull colors, which are crucial indicators for assessing its nutritional and economic value. However, the molecular regulatory mechanisms that govern the hull color of foxtail millet are largely unknown at present. This gap in knowledge
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The foxtail millet exhibits a diverse range of hull colors, which are crucial indicators for assessing its nutritional and economic value. However, the molecular regulatory mechanisms that govern the hull color of foxtail millet are largely unknown at present. This gap in knowledge significantly impedes efforts to enhance the quality traits of foxtail millet. This study utilized a population of 250 F
6 recombinant inbred lines (RILs) generated from a cross between two foxtail millet varieties: Yugu18 (with light yellow seeds) and Hongjiugu19 (with red seeds). Four methods, the visual grouping method (I), the visual colorimetric method (II), the Lab determination method (III), and the RGB determination method (IV), were employed to determine the hull color of each line across four environments and QTL identification were conducted subsequently. It showed that there were 10, 12, 69 and 56 QTLs were detected for hull color through four methods, and these QTLs were integrated into 4, 6, 27 and 25 unique QTLs, respectively. There were three, four, four and four major QTLs. Of which, three major QTLs (
qHC1.1,
qHC1.2 and
qHC9.3) on chromosomes 1 and 9 could be detected by all 4 methods.
qHC9.1 was detected by all four methods except for method I. There were also one, one, seven and four minor identity QTLs identified across the 4 methods. Four minor QTLs (
qHC3.1,
qHC3.3,
qHC4.1 and
qHC5.1) can be stably detected only in method III, and two minor QTLs (
qHC8.2 and
qHC9.2) can be stably detected only in method IV. Generally, method I is fast, efficient and cost-effective, which is suitable for the rapid detection of hull color. Method II is also low-cost; however, it can detect more QTL for hull color, making it suitable for identifying major QTL loci in large populations. Methods III and IV can map more minor QTL and are more accurate in hull color characterization. This study identified four important hull color QTL for foxtail millet, which largely align with those reported in previous research. These findings establish a foundation for characterizing hull color indices and further advancing QTL mapping for grain color.
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