Classification of genotypes of leaf phenotype (P/tan) and seed phenotype (Y1 and Tan1) in tan sorghum (Sorghum bicolor)

Sorghum [Sorghum bicolor (L.) Moench] pigments are associated with resistance to leaf diseases and grain deterioration. As a defence response, tan sorghum produces flavones (apigenin and luteolin), whereas wild‐type sorghum produces additional 3‐deoxyanthocyanidins (apigeninidin and luteolinidin). The dominant leaf colour gene P (Sb06g029550) controls 3‐deoxyanthocyanidin production; the loss of its function results in tan leaves. We investigated the polymorphism of the P gene alleles and found that 11 of 327 lines from sorghum core collections had tan phenotype due to the loss of Sb06g029550 function. Six alleles (with insertions 1–4, a deletion and a point mutation) were found in tan sorghum, most of them in African landraces. This distribution suggests that the tan phenotype arose independently in different geographical locations and was selected several times during sorghum domestication. As plants with white seed without tannin often have tan leaves, the polymorphism of the transcription factor genes Y1 (for white seeds) and Tan1 (for seed tannin) was analysed. The grain coloration was affected by these transcription factors as previously reported but the leaf coloration by wounding was not affected by them.