Cytogenetic study of Helianthus tuberosus and its F, hybrid with cultivated sunflower, Helianthus annuus L.

摘要

The genus Helianthus (Asteraceae) contains 49 species distributed into 4 sections according to the systematics of Schilling and Heiser (1981). The perennial species were distributed taxonomically into different sections and series and possessed different ploidy levels (diploid, tetraploid and hexaploid). Hybridization and study of meiosis and pollen viability in F)1 hybrids showed that belonging to different sections and series is a higher obstacle for interspecific crossing than different levels ofploidy (Georgieva-Todorova, 1990). Among the several hexaploid species, Helianthus tuberosus received great attention since it exhibited high degree of resistance to leaf spot caused by A. helianthi besides its cross compatibility with cultivated sunflower (Sujatha ef al., 1997). In the present investigation an attempt was made to determine the extent of genetic similarity between H. tuberosus and cultivated sunflower i.e., phylogenetic relationship between these two species by studying meiosis and pollen viability in each species and F_1 interspecific hybrids.