Genetic Variation of Lime (Citrus sp.) Accessions Using Flow Cytometry Technique, Morphological Characteristics and Molecular Markers

Because of sexual propagation of Mexican lime in southern regions of Iran, there are many lime accessions (lime biotypes) in Mexican lime gardens in which appear some variation in fruit and tree shape. However, most of these accessions are susceptible to witches broom disease of lime (WBDL). Persian lime (C. latifolia Tanaka) is a triploid WBDL-tolerant species. Considerable number of un-described lime biotypes have been cultivated by farmers as Persian lime with no documented evidence related to their origin and genetic background. To unveil systematic modality of the lime accessions, we investigated 18 lime accessions collected from Fars, Hormozgan and Mazandaran provinces (Iran) using flow cytometry (FCM) approach, morphological characteristics, ISSR and SSR markers in 2016. The results of FCM revealed that 14 out of 18 lime accessions were triploid. Triploid accessions showed higher leaf dimension values together with lower stomata and secretory sacs density compared with diploid accessions. Application of SSR markers confirmed the obtained results of ploidy level determination using FCM and morphological analysis. Results of morphological and ISSR markers demonstrated that four out of 18 accessions were different from others and it was in correspondence with the results of FCM. SSR results also grouped the accessions in line of FCM. In conclusion, it has been shown that IFJKh, Cucumber-shaped lime and IFJKMes accessions, are diploid and their cultivation is not recommended in the infected regions to WBDL phytoplasma.