Assessment of variation in isoproturon in susceptible and resistant biotypes of <i style="">Phalaris minor</i> Retz. by RAPD analysis

Abstract

The extensive use of isoproturon for the control of weeds in wheat fields for the past 20 years has lead to the formation of isoproturon resistant biotypes of <i style="">Phalaris minor</i>. This problem was first identified in Haryana and later in Panjab and some parts of Uttar Pradesh. PCR based RAPD technique, which can detect variability at DNA level was used to assess the variability among the two isoproturon susceptible and two resistant biotypes of <i style="">Phalaris minor</i>. Nine oligonucleotides (10 base) were screened for their ability to produce polymorphic bands. Three primers did not amplify DNA of one or the other biotypes. Three more did not show any polymorphism amongst the biotypes. The rest three indicated 20% polymorphism level. The size of amplified DNA segments ranged from 105 to 1020 base pair (bp). The mean dissimilarity value of these biotypes was 0.19. Highest dissimilarity (0.21) could be observed between the two resistant biotypes. Cluster analysis of the RAPDs generated separated one of the resistant biotypes from rest of the populations. Primer 20 A0 showed maximum polymorphic value of 1.0 between the susceptible biotype from Karnal and the resistant biotype from Kalwehri. This suggests that the technique could be utilized in the assessment of genetic diversity of the populations existing in other states and developing markers for the resistant trait.