3.Genetic characterization of Japanese upland rice and gene block on chromosome II: Chromosomal polymorphic region (CPR)

Yuko harata, Y. tuchimine and R. ishikawA

Faculty of Agriculture, Hirosaki University, Hirosaki 036, Japan

We studied Japanese upland rices for allelic constitution at the isozyme locus, Pgd-I

Research Notes 45

(Phosphogluconate dehydrogenase-1). Almost all the upland rice cultivars possessed allele 2 at Pgd-I locus which has never been found among Japanese lowland cultivars so far examined. as the upland rice specific allele in Japan has been found among the strains classified as Tropical Japonica (Tr-type) and not in Temperate Japonica (Tm-type) defined by Oka (1953), we applied the discrimination method for Tr-type and Tm-type revised by Sato (1991) to Japanese lowland and upland cultivars. Cultivars having Z values smaller than zero are regarded as typical Tm-type and those having Z values larger than zero as Tr-type. Distribution of 55 Japanese lowland cultivars fitted the range of Tm-type (Fig. 1). Fifty-one upland cultivars having allele 2 of Pgd-1 showed intermediate range although they included some typical Tr-type cultivars. Ten upland cultivars belonging to another group having allele 1 showed trimodal curve. The results suggested that the group may consist of heterogeneous types. Such trends were also confirmed with other characters (Table 1).

Fig. 1. Z score distribution among several kinds of rice groups having different genotype for Pgd-I in Japan. Dotted line shows Z score distribution of 55 lowland cultivars, gray line shows that of 51 upland cultivars, Pgd-1^2, and black line shows that of upland cultivars; Pgd-I'.

Table 1. Differences of morphological (APH; apiculus hair length, L/W; ratio of kernel length and width) and physiological characters (phenol reaction) between different genotype for Pgd-I in Japan. Upland growp having allel 1 showed intermediate traits

Group

No. of cultivars

Means(±SD)

Ph reaction of hulls

APH (mm)

L/W ratio

Positive

Negative

Lowland(Pgd-l')

445

0.72+/- 0.19

2.09 +/- 0.34

32

413

Upland(Pgd-1')

26

0.65±0.12

2.14±0.16

5

21

Upland(Pgd-1^2)

169

0.44±0.14

2.38±0.21

131

38

 

46 Rice Genetics Newsletter Vol. 13

Fig. 2. Linkage between kernel weight and PGD genotypes in an F2 population of a cross between lowland and upland cultivars grown in a paddy field. Gray line shows a distribution of homozygous progenies for Pgd-I^2 and black line shows those for Pgd-I'.

Upland-specific gene for field resistance to rice blast fungus has been located near Pgd-I locus on chromosome 11 (Goto 1970; Ishikawa et al. 1991). This gene may be necessary for upland cultivars to survive in an upland field. Some QTL for yield were found also on chromosome 11 by using F2 segregating progeny between lowland (Taichung 65) and upland (Sensho) cultivars grown in a paddy field. One example is shown in Fig. 2. The allele(s) concerned to small kernel weight may be linked to Pgd-I^2 and others may not. However, parental kernel weights showed different tendency. Thus. other factors like panicle length or other QTL relating to yield may be responsible for such trend. (Gene symbol: Old system)

References

Goto, I., 1970. Genetic studies on the resistance of rice plant to the blast fungus. 1. Inheritance of resistance in

crosses Sensho x H-79 and Imochi Shirazu X H-79. Ann. Phytopath. Soc. Japan 36: 304-312.

Ishikawa, R., H. Morishima, T. Kinoshita, T. Harada, M. Niizeki and K. Saito, 1991. Linkage analysis of nine

isozyme genes on the conventional linkage map in rice. Japan. J. Breed. 41: 265-272.

Oka, H.I., 1953. Phylogenetic differentiation of the cultivated rice plant. 1. Variation of various characters and

character combinations among rice varieties. Japan. J. Breed. 3: 33-43.

Sato, Y.I., 1991. Variation in spikelet shape of the indica and japonica rice cultivars of Asian origin. Japan.

J. Breed 41:121-134.