8. Genetic diversity of weedy rice in Malaysia

Duncan A. VAUGHAN, 1 H. WATANABE2 ,Abdullah Md. ZAIN3and K. OKUNO1

1)NIAR. 2-1-2 Kannondai. Tsukuba 305, Japan
2)JIRCAS. Tsukuba 305. Japan
3)Rice Research Center, MARDI. Seberang Perai. Malaysia

Weedy rice has recently become one of the major weeds in two of the main rice production areas of Malaysia. Tanjung Karang and MUDA. We randomly sampled weedy rice from across the entire range of its distribution in these two rice growing areas. 49 samples of weedy rice were analysed from MUDA and 37 from Tanjung Karang. DNA was extracted from each sample and was subjected to RAPD analysis. Polymorphic bands were scored and cluster analysis was performed on the data. Wards coefficient of similarity was measured.

For samples from MUDA 18 polymorphic bands were scored using 12 primers (Fig. 1). For samples from Tanjung Karang, 24 polymorphic bands were scored using 12 primers (Fig. 2). Samples from MUDA showed no clear groupings. However, samples from Tanjung Karang fell into 2 groups with the same number of samples in each group. The phenol test. a test which is indicative of Indica and Japonica races (Oka 1988). was performed on all samples and the results are shown (Table 1 ). The weedy rice samples did have different reactions to phenol and in Tanjung Karang the number of sample which reacted or did not react were almost equal in number. However, the two groups revealed by cluster analysis of RAPD data of samples from Tanjung Karang did not correspond to the groups by phenol test. It seems possible in Tanjung Karang. where weedy rice was a problem for many years, that the early stages of differentiation have been revealed by RAPD analysis, which is a method sensitive to small differences between samples at the DNA level.

 

Reference

Oka, H. I., 1988. Origin of Cultivated Rice. Elsevier/Japan Sci. Soc. Press. Amsterdam/Tokyo, 254pp.