Waxy allelic diversity in common millet (Panicum miliaceum L.) in China

A set of 132 accessions of common millet, Panicum miliaceum L., from 12 provinces of China were assessed for endosperm starch type (waxy or non-waxy) using I₂-KI staining, amylose and amylopectin contents using the dual-wavelength colorimetric method, and genotype of Waxy genes conditioning amylose content by gene sequencing. Endosperm starch content varied from 57.69% to 74.70%, while the amylose and amylopectin contents of the starch ranged from 0 to 23.29% and from 41.99% to 70.24%, respectively. Sequencing two Wx genes, including Wx-L (intron 5-exon 7 and intron 8–9) and Wx-S (exon 9–intron 10) revealed several polymorphisms (S₀, S₋₁₅, L_C, L_F, L_Y). Marker M5-R11 linking to the Wx-S gene may be used to discriminate waxy common millet accessions from non-waxy ones. Among the 132 accessions, 68 with the S₋₁₅ allele had waxy endosperm starch with the amylose content range 0–2.58% and 64 accessions with the S₀ allele had non-waxy endosperm starch with amylose content range 3.94%–23.29%. Five genotypes including S₋₁₅/L_F (45% of the accessions), S₀/L_F (25%), S₀/L_Y (12%), S₀/L_C (11%), and S₋₁₅/L_Y (7%) were identified. Six new SNPs were detected at the Wx-L locus. These results will facilitate common millet breeding, especially of cultivars free of amylose.