Genetic diversity of Iranian madder (Rubia tinctorum) populations based on agro-morphological traits, phytochemical content and RAPD markers

Madder (Rubia tinctorum) is highly valued for antheraquinone pigments produced in its underground parts. Iran is known, as a main producer of madder. Genetic variability present in madder in Iran is not unknown. The main objectives of our research were (1) evaluate phenotypic and molecular diversity among Iranian madder populations; (2) compare dye content between populations originating from different ecological areas; (3) determine possible correlations between dye content and morphological traits; and (4) estimate the broad-sense heritability (h2b) for the traits evaluated. In this study a combined analysis of variance was used to evaluate 12 Iranian populations of madder over a 2-year period. Traits investigated were root weight, shoot weight and dye content. RAPD markers were also used to evaluate molecular diversity. Statistical analysis showed that population had significant effect on all evaluated traits. Duncan's multiple range tests showed that traits evaluated were significantly different among populations. Simple correlation analysis showed that shoot weight had significant positive correlation with root weight and also with dye content (r = 0.534 and 0.493, respectively). The highest estimate of broad-sense heritability was that of shoot weight (h2b = 67.2%). Cluster analysis based on agro-morphological/phytochemical traits or RAPD markers did not reveal a clear relationship between diversity pattern and geographical origin. Furthermore, no association between agro-morphological/phytochemical diversity and molecular diversity pattern was detected. In conclusion genetic diversity of Iranian populations of madder as shown in this study should play a critical role in future selection and breeding of madder.