Identification and genetic diversity analysis of broomrape in Xinjiang, China

Abstract

Background: As a holoparasitic weed, broomrape has seriously threatened the production of economically important crops, such as melon, watermelon, processed tomato, and sunflower, in the Xinjiang Province in recent years. However, the distribution and genetic diversity of broomrape populations in Xinjiang are not clear at present, which hinders their prevention and control process. The purpose of this study is to identify the main species and the genetic differentiation structure of the broomrape population in Xinjiang province. Methods and Results In the present study, 93 samples from different geographic regions of Xinjiang were collected to identify the species based on ITS and plastid rps2 regions, and the samples were also used to analyze the genetic diversity based on ISSR markers. The results showed that broomrape is not monophyletic in Xinjiang and consists of two major clades (Orobanche cf. aegyptiaca and O. cernua) and three subclades (O. cf. aegyptiaca var. tch, O. cf. aegyptiaca var. klz, O. cernua.var. alt) by phylogenetic analysis based on ITS and rps2. Furthermore, the results of the genetic diversity analysis indicated that the 11 selected primers produced 154 repeatable polymorphic bands, of which 150 were polymorphic. The genetic diversity of the samples was 37.19% within populations and 62.81% among the populations, indicating that the main genetic differentiation occurred among the populations. There was less gene exchange between populations, with a gene flow index (Nm) of 0.2961 (<1). The UPGMA dendrogram indicated that most populations with similar geographical conditions and hosts were clustered first, and then all samples were separated into two major groups and seven subclusters. Conclusion The broomrapes are mainly O. cf. aegyptiacaand O. cernua in Xinjiang province, which were separated into two major groups and seven subclusters furtherly based on ISSR markers. This is the first study to clarify genetic diversity and population distribution of broomrape in Xinjiang. Our results provide a theoretical basis for the prevention, control, and breeding of broomrape-resistant varieties.