8. Genetic diversity of weedy rice in Malaysia
Duncan A. Vaughan, 1 H. Watanabe2 ,Abdullah Md.
Zain 3and K. Okuno1
1)NIAR. 2-1-2 Kannondai. T.sukuba 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
MLJDA. 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.
Wards coefficient of discrimination
Fig. 1. Dendrogram showing cluster analysis of DNA polymorphism revealed
by RAPD
analysis of weedy rice from MUDA
Wards coefficient of discrimination
Fig. 2. Dendrogram showing cluster analysis of DNA polymorphism
revealed by RAPD
analysis of weedy rice ( *) from Tanjung Karang and cultigen
(MR84X)(* ).
Table 1. Phenol reaction of weedy rices in Malaysia
| Sampling location |
Number of plants Positive
Negative |
| MUDA |
31 |
4 |
| Tanjung Karang
Cluster 1 |
17
9 |
14
5 |
| Cluster 2 |
8 |
9 |
Plants with a dark hull were excluded.
Reference
Oka, H. I., 1988. Origin of Cultivated Rice. Elsevier/Japan Sci. Soc.
Press. Amsterdam/Tokyo, 254pp.