Inheritance studies for morphological characters and sex expression in pistillate lines of castor (Ricinus communis L.)

Abstract

Inheritance of morphological characters in four crosses of pistillate x pistillate lines indicated that stem colour was controlled by single gene while red stem colour was dominant over green stem colour. However, green stem colour in the cross DPC 13 x M 574 and green colour of petiole, capsules and spines in cross M 574 x DPC 11 showed digenic epistatic ratio to red stem colour, red colour of petiole, capsules and spines. The characters plant type and bloom were monogenically controlled while normal plant type and presence of bloom were dominant over dwarf plant type and absence of bloom respectively. Joint segregation analysis indicated that stem colour, plant type and bloom were segregating independently in all the four crosses. Pistillate character was dominant over pistillate with interspersed staminate flowers [ISF] and controlled by one [P1] or two [P1P2] to four genes [P1P2 P3P4]. Joint segregation analysis indicated linkage between stem colour and dwarf plant type in the cross DPC 13 x DPC 11 and pistillate character [P1] and plant type [PtN] in cross M 574 x DPC 11. The distance between stem colour [Rst/gst] to plant type [PtDw] and single gene for pistillate character and plant type was estimated as 40.2 centimorgans and 47.6 centimorgans based on square root of frequency of double recessive phenotypes in F2 data.