Differential expression of genes due to nucleotide changes responsible for determining bitterness/ sweetness in pummelo (citrus grandis l.) progenies

Abstract Pummelo, though stands nutritionally parallel to mandarin and sweet oranges, it lacks the commercial exploitation due to bitterness caused by naringin flavonoid and limonin limonoid. The present study investigates the genetic basis of bitterness in pummelo, focusing on mutations in the Cm1,2RhaT and UGT gene and their impact on naringin and limonin accumulation respectively. A mutation at 519 bp in HS48-12 resulted in the transversion of arginine (bitter) to serine (sweet), correlating with a lower naringin content (89.52 µg/g). Variation in naringin levels (89.52–336.86 µg/g) was linked to differences in gene expression. Higher levels of bitter amino acids were observed in Acc. 3, HS46-13, and HS48-12, corresponding to increased limonin content, while H17-9 exhibited higher sweet amino acid accumulation and lower limonin content (5.61 µg/g). Understanding these genetic mechanisms can aid in breeding programs for developing non-bitter citrus varieties, improving fruit quality and commercial viability.