22. A new allele at the lg locus conferring short ligules

A mutant with short ligules was obtained in the progeny of an EMS-treated population of Akihikari at the Hokuriku Agricultural Experiment Station in 1984, and its seed was made available through the courtesy of Dr. H. Fujimaki. This mutant, designated as MA85152, had very short ligules, underdeveloped auricles and narrow leaf collars, and showed erect stature. The F\1\ plants of crosses between MA85152 and strains with normal ligules were normal, and the F\2\ populations segregated into 3 normal : 1 short type (Table 1). When MA85152 was crossed with testers having the liguleless gene (lg), the F\1\ plants had short ligules and the F\2\ segregated into 3 short-liguled:1 liguleless type (Table 2). When the F\1\ plants were backcrossed with H-79 or H-59 having the lg gene, the B\1\F\1\ populations segregated into 1 short- liguled:1 liguleless type and no plants with normal ligules were found. These data indicate that MA85152 possesses a short ligule gene allelic to lg, which is symbolized lg^a. The dominance relation will be: lg⁺>lg^a>lg.

The linkage relations between lg^a and Pl (purple leaf) were examined in the F\2\ of H-126xMA85152 and their recombination value was estimated to be 31.4+=5.3% (Table 3). This value is close to those so far obtained between lg and Pl, 30.9% by Nagao and Takahashi (1963) and 29.4% by Kinoshita and Takamure (1987).

Recently, an auricleless gene (aul) was reported by Librojo and Khush (1986), which belonged to the second linkage group but was not allelic to lg. Although lg^a and aul are similar in character expression, they are different genes whose loci could be linked.

Table 1. F\2\ ratios for normal and short ligule types MA85152-short liguled; others-normal; all F\1\'s-normal.

Table 2. Segregation for short ligule and liguleless (lg) types in F\2\ and B\1\F\1\ populations MA85152-short liguled; other parents-liguleless; All F\1\ plants-short liguled.

Table 3. Recombination value obtained between lg^a (short ligule) and Pl(purple leaf) combined in coupling in the F\2\ of H-126XMA85152(5)

Kinoshita, T. and I. Takamure, 1966. Linkage studies by the use of backcross data in rice. Genetical studies on rice plant, 95. J. Fac. Agr. Hokkaido Univ. 63: 136-143.

Librojo, A.L. and G.S. Khush, 1966. Chromosomal location of some mutant genes through the use of primary trisomics in rice. In Rice Genetics, p. 249-255. IRRI, Manila.

Nagao, S. and M. Takahashi, 1963. Trial construction of twelve linkage groups in Japanese rice. Genetical studies on rice plant, 27. J. Fac. Agr. Hokkaido Univ. 53: 72-107.