Inheritance of a Shriveled Seed Trait in Peanut

Abstract

A seed shrivelling trait in groundnut (Arachis hypogaea) was identified that severely affected seed morphology and lipid deposition. This character also showed partial penetrance and variable expressivity within true-breeding shrivelled lines. Also, both normal and shrivelled seed were produced from plants grown from either normal or shrivelled seed from these lines. Knowledge of the genetic basis for this trait is important for understanding the biosynthetic lesion involved and for manipulation of the trait in breeding programmes. Three shrivelled-seeded lines (529B, 563A and 647A) were crossed to a normal-seeded cultivar, Sunrunner, and intercrossed. Crosses with shrivelled seed genotypes as male parents with Sunrunner showed that this trait is under the control of a single recessive gene. However, no segregation of shrivelled types was observed in the F2 of the reciprocal crosses when shrivelled lines were used as female parents. Segregation was observed in the F3 generation (F4 seed) for these crosses. The paternal expression may be due to male transmission of extrachromosomal factors like plastids or mitochondria, or may be caused by a phenomenon like genomic imprinting. Only shrivelled F1 and F2 seeds were obtained from the crosses among the three shrivelled lines, indicating that only one locus was involved in the expression of this trait in these three genotypes.