Genetical control of amylose content in a diallel set of rice crosses

Abstract

Models proposed by Gale and Pooni, Kumar and Khush are applied to study the inheritance of amylose content in a diallel set of crosses produced from seven elite inbred lines of indica rice representing all the major rice consuming regions of the world. In theory, the standard (Hayman's and Griffing's) analyses of diallel tables and the Wr/Vr relationship are found to apply even though the trait under investigation is expressed in a triploid state. It is further revealed that reciprocal effects can only be detected unambiguously in the F₂ diallel and the additive and non-additive effects cannot be separated in the B₁ and B₂ diallels when they are analysed separately. Analysis of the experimental data reveals that additive and dominance effects are the main sources of variation among the 21 crosses of the 7 times 7 diallel. Comparisons of the B₁ and B₂ diallels also show that the single dosage dominance (h_a1 type) effects differ significantly from the double dosage dominance (h_a2 type) effects. In addition, cytoplasmic control of amylose content is confirmed unambiguously and a large proportion of the heritable variation is shown to be controlled by a series of multiple alleles with large effects.