BGN 2: Another case of paracentric inversion in a genetic stock, Engleawnless, for Lk of barley BARLEY GENETICS NEWSLETTER, VOL. 2, II. RESEARCH NOTES
Tsuchiya and Singh, pp. 110-111

II.46. Another case of paracentric inversion in a genetic stock, Engleawnless, for Lk of barley.

T. Tsuchiya and R. J. Singh. Department of Agronomy, Colorado State University, Fort Collins, Colorado 80521, U.S.A.

Supported in part by NSF Research Grant GB 30493 and Colorado State University Experiment Station Project (Hatch 8).

It has been known for quite some time that there is no recombination between Vv alleles and Lklk alleles on chromosome 2 when the genetic stock Engleawnless for a dominant short awn gene Lk and two-rowed gene V was used in crosses with a six-rowed, long awn stock (lk v) (Engledow, 1924; Wiebe, 1972). Wiebe (1972) suggested the existence of an inversion to explain this phenomenon.

Kuckuck (1930), however, reported the crossover value of 9.6% between Vv locus and Lklk locus, though allelic relationship of the stocks for awnless used by Engledow and those used by Kuckuck has not been tested.

The present writer has been conducting a critical genetic analysis of glume characters of barley including the effects of short awn and awnless genes on the expression of glume awn, because of rather confusing results so far reported for glume characters (Robertson et al. 1955; Helgason, 1964; Robertson, 1971). During this experiment, F1 hybrids from various cross combinations, including Engleawnless as one of the parents, were grown in the greenhouse.

The finding of a paracentric inversion in a genetic stock for white streak (wst 3) (Tsuchiya, 1972) has stimulated the present writer to study the cytological behavior of F1 hybrids between Engleawnless and other genetic stocks. Meiosls of an F1 hybrid between Engleawnless and a wide outer glume mutant (Stock Ab 1457) was studied.

A bridge-fragment configuration was found at anaphase I of meiosis of the above-mentioned hybrid. The frequency of sporocytes with bridge-fragment was very low.

From these results it is concluded that Engleawnless has a paracentric inversion in one of its chromosome pairs. At present, there is no evidence to prove that the paracentric inversion is in chromosome 2. A critical cytogenetic analysis is being conducted by means of trisomic analysis to associate this paracentric inversion with the particular chromosome.

The present writer suggests barley workers not to use Engleawnless for genetic and linkage studies until this problem is solved.

References:

Engledow, F. L. 1924. Inheritance in barley. III. The awn and lateral floret: fluctuation: a linkage: multiple allelomorphs. Jour. Genet. 14:49-87.

Helgason, S. B. 1964. Inheritance of glume characteristics in some barley crosses. Barley Genetics I (Proc. Ist Intern. Barley Genet. Symp.):181-185.

Kuckuck, von H. 1930. Versuche einer vollaufigen Chromosomentopographie bei Gerste. Zuchter 3:68-72.

Robertson, D. W. 1971. Recent information of linkage and chromosome mapping. Barley Genetics II (Proc. IInd Intern. Barley Genet. Symp.):220-242.

Robertson, D. W., G. A. Wiebe, R. G. Shands. A Summary of Linkage Studies in Barley: Supplement II, 1947-1953. Agron. Jour. 47: 418-425.

Tsuchiya, T. 1972. A case of paracentric inversion affecting genetic behavior of a white streak gene. BGN 2:104-105.

Wiebe, G. A. 1972. Tight linkage of the awnless gene in Engleawnless with the Vv locus. BGN 2:108.

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