35. Alien addition lines of rice with an extra chromosome bearing resistance genes for blast and bacterial leaf blight diseases

Chang-Duk Lee and Young-Boum Shin

Department of Agronomy, Kangweon National University Chuncheon 200, Korea


When a single resistance gene is introduced into a variety by backcrossing, the resistance will be subjected to vulnerability in a few years. We have attempted to incorporate single chromosomes of a resistant variety into a susceptible one. "Lead-rice" is resistant to both blast and bacterial leaf blight diseases. Triploid plants obtained from Sekitori (4X)xLead-rice (2X) were backcrossed with Skitori (2X). From this cross, 12 different types of alien addition lines (trisomics, 2n=25) with a single Lead-rice chromosome were obtained. Their morphological characteristics were as follows:

Type A: Long grain, dropped leaves, low seed fertility (20%).

Type B: Large grain, low seed fertility (14%).

Type C: Thick stem, short and erect flag leaves.

Type D: Sterile, similar to type C in other respects.

Type E: Dark green leaves, sterile.

Type F: Long grain, erect flag leaves, thin stem, rolled leaves, imperfect panicle emergence, sterile.

Type G: Round grain, deciduous, short height, rough leaves, sterile.

Type H: Large grain, large ligule, thick stem, rolled leaves, sterile.

Type I: Long grain, deciduous, small ligule, narrow leaves, short height, wide angle of flag leaves, thin stem, sterile.

Type J: Purple apiculus, thin stem, many tillers, sterile.

Type K: Thin stem, many tillers, rolled and drooped leaves, sterile.

Type L: Awned, short height, rolled leaves, imperfect panicle emergence, sterile.


The chromosome configurations observed at PMC metaphase I of these trisomic plants were 12II+1 I or 1 III+11 II.

The alien additional lines and disomic lines were tested for resistance to the blast disease. Of 71 trisomic plants tested, 32 showed field resistance. One of them, LO 04, showed verticle resistances to all six races of the blast fungus, T-2, C-1, N-2, T-2+t, C-8+t and N+t. Other 12 plants also showed medium to high resistance to these fungus races. Of 21 disomic plants tested, 6 showed field resistance, and two of them, LO 92 and L 242, showed true resistances to all the six races. The test of the 12 morphological types of alien addition lines indicated that the extra chromosomes of type C,D,K, and L would bear resistance genes.