BADH1 is associated with fragrance in sorghum (Sorghum bicolor (L.) Moench) cultivar 'Ambemohor'

Aroma is an important trait that can enhance the product value in several crops. Pandan-like fragrance resulting from accumulation of 2-acetyl-1-pyrroline (2AP) is one of the pleasant aromas in food crops which is caused by null or missense mutations in betaine aldehyde dehydrogenase 2 (BADH2) gene. In addition, betaine aldehyde aehydrogenase 1 (BADH1) has shown to be associated with aroma in rice. In this study, we investigated the genetics controlling coconut juice-like fragrance in inflorescence of sorghum cultivar 'Ambemohor'. 2AP analysis in seeds revealed that Ambemohor possessed no 2AP. An F-2 population developed from the cross between Ambemohor x KU630 (nonfragrant) segregated into a ratio of 3 (fragrant) : 1 (nonfragrant), suggesting that the coconut juice-like fragrance in Ambemohor is controlled by a single dominant gene, designated 'Aro'. Bulked segregant analysis suggested that the gene controlling fragrance in Ambemohor is located on sorghum chromosome 6. Quantitative trait locus (QTL) analysis identified a major QTL, qAro6.1, for the fragrance located on chromosome 6 between markers SB3567 and SB3570. Bioinformatics analysis revealed that SB3567 and SB3570 were 217.8 kb apart and there were 29 annotated genes in this region including BADH1. Sequence analysis revealed that BADH1 sequences in Ambemohor and KU630 differed in size, but their coding sequences (CDS) were of same size. CDS alignment revealed four single-nucleotide polymorphisms (SNPs) between Ambemohor and KU630 in which two SNPs caused amino change in BADH1 of Ambemohor. These results suggested that BADH1 is a candidate gene for the coconut juice-like fragrance in Ambemohor.