Chromosomal interchange linkage studies with the high lysine gene (hl) in sorghum (Sorghum bicolor (L.) Moench);
Abstract
The discovery of the high lysine (h1) gene opened new horizons in the search for improved nutritional quality of sorghum. Although the h1 gene is inherited as a simple recessive, the chromosomal linkage is unknown. The primary objective of this study was to determine the chromosomal linkage relationships of the high lysine gene (h1) discovered in two naturally occurring lines from Ethiopia. These lines, IS11167 and IS11758, and the converted high lysine lines N82, N93, and N94 from India were crossed with a set of 18 chromosomal reciprocal translation stocks. Progenies of these crosses were grown in the F$\sb2$ generation. The presence of the h1 gene in the F$\sb1$ progeny, was verified by the determination of protein and lysine concentration of the kernels. Pollen and ovule sterility were used to identify semisterile plants, and chi-square tests for goodness of fit to a 3 plump: 1 dent ratio were also conducted. Independence X$\sp2$ test and fixed ratio X$\sp2$ for linkage were conducted for the F$\sb2$ data. The maximum likelihood method in terms of x (x = (1 $-$ p)) was used to estimate the frequency of recombination. Some crosses deviated from a 3:1 ratio. Allelism tests between the two sources of the high lysine gene indicated that they were allelic. The analysis of the data gave strong evidence of linkage between the h1 gene and T28(BH) and T72(BE). This suggested that the h1 gene was linked with the break-points in chromosome B since this chromosome is common to both translocations. However, results from T8(AB), T10(BC), T15(AE), T26(EF), T42(FH), and T45(BH) which carried either chromosome B, E, or H were not clear or consistent. Since T72 gave lower recombination values (i.e. 10.05 to 14.85%) than did T28 (i.e. 15.58 to 23.61) the h1 gene may be linked more closely to the break-point of T72 than of T28. Linkage tests with T1(AD), T16(FJ), T24(FJ), T25(DG), T29(GI), T33(CI), T48(DI), and T69(CJ) indicated that the h1 gene was segregating independently from the break-points on chromosomes A, C, D, F, G, I, and J.
Degree
Ph.D.
Advisors
Axtell, Purdue University.
Subject Area
Genetics
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