Karyotypic studies of the genus Cuscuta L. (Convolvulaceae) in Saudi Arabia and their taxonomic significance (original) (raw)

Chromosome numbers and karyotype criteria of nine species of the genus Cuscuta L. (Convolvulaceae) in Saudi Arabia were investigated. Chromosomes counts were recorded in four species for the first time in this study. Chromosome number, based on x=7 has been found in the majority of the studied Cuscuta species. A diploid number (2n=14) was recorded in five species, while tetraploid number (2n=28) was recorded in two species whereas 2n=56 was recorded in C. campestris. However, 2n=30 based on x=6 was recorded in C. monogyna. The chromosomes in the studied species of Cuscuta are generally small with a mean size ranging between 0.74 and 1.10 μm. Short chromosomes were particularly found in C. planiflora (MCL=0.74 μm) and C. chinesis (MCL=0.79), whereas longer chromosomes were scored in C. campestris (MCL=1.10). The karyotype in the studied species is mostly comprised of metacentric to submetacentric chromosomes as indicated by their mean arm ratio that ranges between 1.31 in C. monogyna and 1.83 in C. planiflora. The degree of karyotype asymmetry is indicated by high values of TF% ranges between 28.33 in C. planiflora and 40.54 in C. campestris. The A1 value ranged between 0.22 in C. planiflora and 0.43 in C. palaestina. Among the examined species, karyotype features were used to assess the Sherif M. Sharawy 66 classification of the Cuscuta species in Saudi Arabia in the light of the current systems of classification.

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