Resistant (R) and susceptible (S) biotypes of Eleusine indica were collected from four areas, namely Chaah, Lenggeng, Bidor and Temerloh, in Malaysia. Restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR)-RFLP analyses using SphI restriction enzyme were able to differentiate the R biotype from the S biotype by showing R-specific and S-specific polymorphisms in E. indica from three of the areas, with the exception of Temerloh where no polymorphisms were detected. The different DNA profiles for the R biotypes obtained indicate that SphI is not a useful diagnostic marker. The DNA polymorphisms detected in the 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase gene suggest that there are different mutation events leading to development of resistance to glyphosate. Partial sequencing of the EPSP synthase gene confirmed different mutations occurring with substitution of proline with serine or threonine at amino acid 106 for the R biotype in Chaah, Bidor and Temerloh.

Glyphosate-resistant populations of Eleusine indica (L.) Gaertn. were found in 4 areas in Malaysia that had received repeated applications of glyphosate for a period ranging from 5 to 15 years. The resistance ratios calculated from dose-response experiments were 2.9 (Chaah), 2.1 (Lenggeng), 3.3 (Bidor), and 2.8 (Temerloh). Two-point mutations were detected in position 875 within the 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) gene resistant population, causing a C to T transition leading to Pro106 to Ser106 substitution in Bidor and Temerloh or C to A transversion leading to Pro106 to Thr106 substitution in Chaah. Sequence comparisons of the 3115 bp of the EPSPS gene revealed identical sequences in both the susceptible (S) and resistant (R) populations of Lenggeng. The identical sequences in both the Lenggeng populations, S and R, suggest that the resistance mechanism found in Lenggeng R may be different from Chaah R, Bidor R, and Temerloh R. The polymerase chain reaction (PCR) amplification of specific alleles (PASA) was developed to detect 2 distinct single-point mutations, probably conferring herbicide resistance in Chaah R, Bidor R, and Temerloh R. PASA profiles showed only one DNA fragment for the entire S population and 2 different additional fragments, each specific for one resistance allele, for the R population.

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