Genetic variability within and between apomictic Guayule (Parthenium argentatum Gray) lines

Guayule (Parthenium argentatum Gray), a semidesert shrub was evaluated as a potential rubber crop. Since polyploid guayule reproduces by apomixis, progeny of individual plants should duplicate the characteristics of their parent. This study was conducted to estimate variations within and among progeny families from single-plant selections. Ten progeny per family were individually evaluated for plant height, width, fresh and dry weight of clipped branches, rubber and resin content, and yield. Leaves of selected plants were analyzed by gradient polyacrylamide gel electrophoresis for esterase and peroxidase to estimate genetic relatedness between parents and progenies. Negative correlation was between parents and progenies for most characters, but none were statistically significant from zero. This suggests a low heritability for the characters measured. Esterase and peroxidase detected variation in banding between parents and progenies and among progenies. This study suggested that out-crossing and meiotic reduction have occurred among apomictic guayule lines.