Inheritance of high palmitic acid content in the sunflower mutant CAS-12 and its relationship with high oleic content

CAS-12 is a sunflower mutant with increased levels of palmitic (C16 : 0 = 30%) and oleic (C18 : 1 = 55%) acids in its seed oil, hence it has a :deduced linoleic acid content (C18 : 2 < 5%). This study was conducted to determine the inheritance of high C16 : 0 content and its relationship with high C18 : 1 content in CAS-12. Reciprocal crosses involving CAS-12, CAS-5 (high C16 : 0 content), HAOL-9 (high C18 : 1 content) and HA-89 (standard fatty acid profile) were made. The F-1, F-2 and BC1F1 generations were obtained. The genetic control of the high C16 : 0 trait in CAS-12 was partially recessive and gametophytic. In all cases, this character segregated in the ratio 19 : 38 : 7 (low : intermediate : high C16 : 0 content) in the F2 generation. These results, together with the lack of segregation for C16 : 0 content in crosses between CAS-12 and CAS-5, indicated that the genetic control of the high C16: 0 trait in CAS-12 was similar to that in CAS-5 in being controlled by partially recessive alleles (p1, p2, and p3) at three loci. Crosses between HA-89 and CAS-12, and HAOL-9 and CAS-5 (segregating for C16 : 0 and C18 : 1) demonstrated that the high C16 : 0 and the high C18 : I traits were independently inherited. However, C18 : I segregation in these crosses exhibited reversal of dominance. Apparently, the low C18 : 1 parental lines carried modifier genes causing the devation.