Biodiv Sci ›› 2019, Vol. 27 ›› Issue (2): 168-176.DOI: 10.17520/biods.2018224

• Original Papers • Previous Articles     Next Articles

Comparison of taxonomic morphological characteristics between Rorippa indica and R. dubia

Tu Weifeng1,Zhang Yang2,3,*(),Tang Jie2,3,Tu Yuqin2,3,Xin Jiajia2,3,Ji Hongli4,Zhang Nanfeng2,Zhang Tao2   

  1. 1 Jiangxi Academy of Agricultural Sciences, Nanchang 330200
    2 Crops Research Institute of Jiangxi Academy of Agricultural Sciences, Nanchang 330200
    3 Jiangxi Province Key Laboratory of Oil Crops Biology, Nanchang 330200
    4 Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi 332900
  • Received:2018-08-13 Accepted:2019-01-02 Online:2019-02-20 Published:2019-04-16
  • Contact: Zhang Yang

Abstract:

The taxonomic status of Rorippa indica and R. dubia remains controversial. In order to clarify the taxonomic relationship between them, the differences of taxonomic characteristics and cytogenetic between both of them were systematically investigated by means of morphological index measurement, DNA relative content detection, somatic chromosome observation and genetic distance analysis based on SSR markers. Our results showed that R. indica (2n = 48) was hexaploid and R. dubia (2n = 32) was tetraploid. Consistently, the DNA relative content of the former was about 150, which was 1.5 times that of the latter. Genetic distance analysis based on 45 SSR markers indicated sister relationships between R. indica and R. dubia. However, they could be divided into two species when the threshold of genetic distance was set as 0.23, which was the genetic distance between two well separated species, R. globosa and R. sylvestris. Meanwhile, the two taxa could be readily distinguished by pod length and seed density. In addition, obvious reproductive barriers were observed between them. The seed setting rates of self-pollinated R. indica and R. dubia were 97.73% and 95.65%, respectively, while that of R. indica cross-fertilized by the pollens from R. dubia was 0. In comparison, the seed setting rate of R. dubia cross-fertilized by the pollen from R. indica were 47.06%, but the germination rate of these seeds was zero. In conclusion, R. indica and R. dubia should be regarded as two species

Key words: Rorippa indica, Rorippa dubia, evolution, cytogenetics, classification