Interspecific hybridization between H. pumilus Nutt. and H. annuus L. and their potential for cultivated sunflower improvement

Abstract

Successful interspecific hybridization was carried out between the wild perennial diploid species Helianthus pumilus Nutt., accession GT-M-172, and cultivated H.annuus L. The cross compatibility between H.pumilus and H.annuus was much higher when the wild species was used as the male in the crosses. Insemination (seed set) was very low in both directions. In order to prove the presence of considerable variability in the early F 1 generation, some statistical methods were used for evaluation of morphological traits such as plant height, head diameter, number of disk flowers and insemination. Heterosis was detected for plant height. Cases of partial to complete dominance of the cultivated parent prevailed. A high level of segregation was observed in the F 2 generation, therefore, traits depression and transgression were evaluated for plant height, head diameter, number of florets and seed set. A triple phenotypic correlation appeared between three characters in sunflower and one of them was confirmed on genetic level as well. Resistance to Plasmopara helianthi, Orobanche cumana and Phomopsis helianthi was discovered in different progenies of the interspecific hybrids of H.pumilus.

Effect of a Geographic Barrier on Adaptation in the Dwarf Sunflower (Helianthus pumilusNutt.)

“…First, selfing rates were low ( fig. 4; table B8); thus, there is substantial self-incompatibility in H. pumilus, as noted by others (Nikolova et al 2004). This validates the experimental approach used to estimate fertility rates in the isolation plots by implying a low rate of seed set due to pollen flow from outside the plots.…”

“…Improvement of the cultivated sunflower relies on introgression of valuable traits from wild, related species (Dorrell and Whelan 1978). Helianthus pumilis is of agricultural interest because of its pathogen resistance and its capacity to produce seeds with high linoleic fatty acid content under conditions that, in agricultural terms, would be considered extreme drought (Seiler 1994;Nikolova et al 2004). Barriers to hybridization with the cultivar are strong but incomplete, and fertile offspring, though not documented in the wild, have been produced under controlled conditions (Nikolova et al 2004).…”

“…Helianthus pumilis is of agricultural interest because of its pathogen resistance and its capacity to produce seeds with high linoleic fatty acid content under conditions that, in agricultural terms, would be considered extreme drought (Seiler 1994;Nikolova et al 2004). Barriers to hybridization with the cultivar are strong but incomplete, and fertile offspring, though not documented in the wild, have been produced under controlled conditions (Nikolova et al 2004). Helianthus pumilus is a convenient system to study the effect of barriers to gene flow on adaptation because of an obvious distributional disjunction, easy access to the entire species range, free availability of seeds in the US National Plant Germplasm System from comprehensive sampling expeditions in the wild, and transferable molecular markers from the cultivar.…”

Utilization of Sunflower Crop Wild Relatives for Cultivated Sunflower Improvement

“…argophyllus have high field tolerance to Phomopsis brown stem canker (Škorić, 1985). Nikolova et al (2004) observed field resistance to stem canker in progenies of interspecific hybrids of perennial Helianthus pumilus Nutt. Field resistance to Phomopsis was reported in interspecific hybrids derived from H .…”