Inheritance patterns in hybrids between Sorghum almum Parodi and perennial sweet Sudan grass

Abstract

Juicy stem and brown plant colour are mainly tetrasomically inherited in hybrids between Sorghum almum (2n = 40) and perennial sweet Sudan grass (2n = 40). Tetrasomic inheritance is also indicated for weak midrib development and dwarf habit. The juicy stem and brown plant colour characters are linked, and the chromosomes on which these genes are situated may pair preferentially and give a 15 : 1 segregation ratio, instead of pairing at random and giving a tetrasomic segregation ratio of 35 : 1. The capacity of these chromosomes to pair preferentially may be under genetic control. It is possible that preferential pairing is part of a general diploidization process, which has led to a reduction in quadrivalent formation and increased meiotic stability in the tetraploid sorghums.