Matromorphy in Nicotiana rustica

Abstract

SUMMARYThe possibility of obtaining instant pure-breeding lines by matromorphic seed development in If. rustica has been investigated. Maternal parents homozygous for recessive marker genes and heterozygous for dominant marker genes were pollinated with different .Jficotiana species and with irradiated pollen of a X rust lea variety having a dominant marker. Poilinations 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 x Vi) maternal parent pollinated with N. tangsdorffi (2n = 18). Poilinations with 3v. 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 isogenie lines as an alternative to recurrent backcrossing.

Overcoming incompatibility and promoting genetic recombination in flowering plants

“…We have now achieved transformation of the egg in four distinct species of Nicotiana, and in addition Virk et al (1977) in Birmingham have independently shown a similar result for a further species of Nicotiana, N. rustica. The method is applicable to both self-compatible and self-incompatible female parents.…”

Gametic gene transfer in indian mustard (Brassica juncea (L.) coss.)

“…A modification of this technique involves the use of highly irradiated pollen not for producing true matromorphs but for the limited transfer of characters from one genotype to another. Evidence has been presented for the success of irradiated pollen technique in effecting the selective transfer of both qualitative and quantitative traits in Nicotiana (Virk et al, 1977;Pandey, 1978; Caligari et a!., 1981) and barley (Powell et a!., 1983). The experiments described in this paper report such an attempt in Indian mustard.…”

Gene transfer in Nicotiana rustica by means of irradiated pollen. I. Unselected progenies

“…Despite reports of its widespread occurrence in this and other genera (e.g., Goodspeed, 1954;Eenink, 1974a, b) the attempts met with only limited success. When heavily irradiated pollen was used, many of the offspring, although not strictly matromorphic (since families derived from them segregated for one or more of the parental differences), did show a general resemblance to their mothers (Virk et a!., 1977). Subjecting the pollen of N. rustica to near-lethal doses of radiation therefore appeared not to produce true matromorphy but to offer the possibility of transferring parts of the DNA from one genotype to another (Mather, 1981).…”