Matromorphy in Nicotiana rustica

Abstract

The possibility of obtaining instant pure-breeding lines by matromorphic seed development in N. rustica has been investigated. Maternal parents homozygous for recessive marker genes and heterozygous for dominant marker genes were pollinated with different Nicotiana species and with irradiated pollen of a N. rustica variety having a dominant marker. Pollinations with 65 species and with irradiated varietal pollen receiving doses ranging from 8 to 40 kr X- and gamma rays were performed on as many as 40 maternal genotypes. Promising matromorphic progenies were studied for the segregation of marker genes and several quantitative characters and for cytological abnormalities in the first and second generations following their induction. Of the numerous pollinations only one homozygous diploid maternal was recovered from F1 (V5 × V1) maternal parent pollinated with N. langsdorffi (2n = 18). Pollinations with N. langsdorffi, however, consistently and frequently induced haploids or near haploids. The evidence gathered over many years of experimentations throws serious doubt on the possibility of using matromorphy as an alternative method of producing pure-breeding lines in N. rustica. Transfer of a dominant marker gene from the irradiated pollen to a triple recessive maternal parent has prospective applications in the production of isogenic lines as an alternative to recurrent backcrossing.