Interspecific hybrid between silver leaf sunflower (Helianthus argophyllus T. & G.) and cultivated sunflower: Cytomorphological characterization of F1 hybrid

Hybrid plants were obtained by crossing cultivated sunflower (Helianthus annuus L., 2n=2x=34) lineARM-243B and a wild Helianthus species [H. argophyllus; 2n=2x=34; HEL-153/83 (PI-649865)], using the latteras pollen parent. The wild Helianthus accession was selected for this study because of its short duration and short plant height compared to other accessions of H. argophyllus. Morphological and cytological analyses were carried out to confirm the hybrid nature of the F1 plants. The hybrids exhibited morphological features intermediate to both the parents for few attributes and more related to wild Helianthus species like leaf and stem pubescence, stem hairiness, flower colour, stem size, branching, disc floret pigmentation, plant height, seed size and seed shape etc. A reduction in pollen fertility (87.5%) was recorded in F1 plants as compared to both the parents. Meiotic analysis revealed a mixture of univalents, bivalents, trivalents and quadrivalents in all the pollen mother cells (PMCs) analysed. In addition to bivalents and univalents, a trivalent was also observed in few PMCs, indicating segmental homology between chromosomes. Frequently observed chromosome configurations in diakinensis were 15 II + 1 IV and 13 II + 2 IV. The results suggested that the species H. argophyllus and H. annuus differ by 1-2 translocations and 1-2 inversions. Results show that the wild species is compatible with cultivated sunflower and using H. argophyllus cultivated sunflower can be improved for biotic (downy mildew) and abiotic stresses (drought and salinity).