Genetics of flesh color and nucleotide sequence analysis of phytoene synthase gene 1 in a yellow-fruited tomato accession PI114490

Abstract

Yellow flesh color in tomato is believed to be caused by abnormal transcript of phytoene synthase gene 1 ( Psy1). However, our initial work indicated that a yellow-fruited line PI114490 might have full length of genomic DNA sequence for Psy1. To understand the genetics of flesh color in PI114490, we crossed this line to red-fruited lines, OH9242 and LA3189, to develop F 1 and F 2 progenies, and sequenced the genomic DNA fragment of Psy1 from PI114490 and OH9242. All F 1 plants had red fruits, and F 2 populations segregated as 3:1 for red and yellow, indicating that one single recessive gene controlled the yellow flesh color in PI114490. This gene was allelic to the known r gene based on tests between PI114490 and four r mutants LA2056, LA3003, LA0353, and LA3532. Sequence analysis indicated that PI114490 had a complete genomic DNA sequence for Psy1 gene with only one nucleotide difference in the fourth intron: G in PI114490 and A in OH9242. This substitution was associated with yellow flesh in the F 2 population. There was no detectable or very low lycopene in PI114490 and all yellow-fruited F 2 individuals. Lycopene in the F 1 (9.77 mg/100 g) was higher than the mean (6.52 mg/100 g) of two parents, and ranged from 0 to 11.69 mg/100 g in all red-fruited F 2 individuals. These results suggested that lycopene content was quantitatively inherited.