Genetic and morphologic characteristics of the gigantic mutant of oats, Avena saliva L

Abstract

Abstract. A gigantic mutant (gig-a) isolated from cv. Hannes is described. The mutant is lush, many-noded and late ripening not reaching, maturity during The late-maturing, gigantic mutants of the common oats are easily observed even by a layman at harvest time. By that time, the broad-leafed (up to 4.5 cm), green mutants are only at the vegetative stage. A mutant plant is especially easy to detect when the normal oats remain low, for instance due to an early summer drought. Being very late, none of the mutant plants seed in Finland, but are selected away from the seed crop every year. Nevertheless, the mutants can be considered to be very common in some seasons (Kivi 1968). This condition is presumably attained by either (1) a segregation of the previous year's overdominant heterozygotes, or (2) this impression may be due to an exceptionally good exposure of the mutants from the rest of the stand owing to seasonal factors favourable to the growth of the mutant. The first hypothesis is discussed in this paper.The present mutant line designated by the name HA 68-2 was established from a single plant of cv. Hannes in 1968. Since very little has been reported about the inheritance of the gigantic oats, HA 68-2 was tried as backcross to Hannes. This proved difficult, however resulting only in a few seeds during the two seasons the cross was attempted.Zillinsky (1959) describes a'monster' mutant in oats, which is very similar to the gigantic ones. His report is apparently the only one about the inheritance of this type of oat mutants.

Unfecund, gigantic mutant of oats (Avena sativa) shows fecundity overdominance and difference in DNA methylation properties

“…Although only the yield differences by weight in cv Kyro were statistically significant, all four experimental items consistently displayed a higher yield when the gig gene was heterozygous . If the 13 .6 percent point lower grain mass measured in F l heterozygotes with Hannes (Ahokas, 1976a) is assumed, there is significant overdominance of fecundity also in Hannes material. The space-planted F6 population contained two thirds of heterozygous or segregating rows of plants and one third of unsegregating rows .…”

“…The Hannes oats used to evaluate heterosis in the season of 1986 were F 6 segregants of a single F2 plant, which was a derivative of the cross HA68-2 x Hannes, where HA68-2 is a gig/gig mutant line of Hannes (Ahokas, 1976a) . The gigantic Kyro line was obtained from Mr. O .…”

“…heterozygotes of the gigantic gene (+/gig) produced 2 .5 times the kernel numbers of nonmutant cv Hannes under wide space conditions (Ahokas, 1976a) . The heterozygotes had a threeday longer vegetative development than the nonmutant, whereas they reached maturity with a delay of about one day .…”

“…The data below support the existence of overdominance or monogenic heterosis of grain yield . The homozygous gigantic plants are poorly heading and extremely late-maturing and being eliminated from the seed crop (Ahokas, 1976a) .…”

“…Several different gigantic mutants in oats have been described (Schegalow, 1922 ;Schwanitz, 1954 ;Schwanitz & Pirson, 1955 ;Zillinsky, 1959;Kivi, 1968 ;21 Gielo, 1969 ;Ahokas, 1976a;Kibite & Taylor, 1994 ;Taylor et al ., 1995) . The gig locus studied by Kibite & Taylor (1994) shows linkage with the multiflorous spikelet (Mf-1) and also with the hullessness (N-1) locus .…”