Biology Reference
In-Depth Information
460 g/kg, the highest ever observed in a wild sunflower species (Seiler
2007), followed by H . niveus ssp. canescens with 402 g/kg, H . petiolaris with
377 g/kg, and H . deserticola with 343 g/kg. Perennial H . salicifolius has a
concentration of 370 g/kg (Seiler 1985; Seiler and Brothers 2003). Cultivated
sunflower generally contains 450 to 470 g/kg. The linoleic fatty acid
concentration in the oil of H . anomalus populations was uncharacteristically
high for a desert environment, approaching 700 g/kg (Seiler 2007). A linoleic
acid concentration of 540 g/kg in H . deserticola is more typical for a desert
environment. Cultivated sunflower grown at northern latitudes generally
have linoleic acid contents of over 680 g/kg, while southern latitudes have
approximately 550 g/kg. Reduced concentrations of saturated palmitic and
stearic fatty acids have been observed in a population of wild H . annuus that
had a combined palmitic and stearic acid concentration of 58 g/kg (Seiler
1998). This is 50% lower than in oil of cultivated sunflower. A combined
palmitic and stearic acid concentration of 65 g/kg was observed in a wild
perennial species, H . giganteus (Seiler 1998).
1.5.5.5 Cytoplasmic Male Sterility
Sunflower is the only Asteraceae in which the cytoplasmic male sterile (CMS)
system is known. Cytoplasmic male sterility is sporophytic in sunflower
(Pearson 1981). Sunflower plants that are CMS usually have anthers one-
half the normal length, which does not project from the corolla (Leclercq
1969). Anthers in male sterile lines are fused only at their bases, and not at
their tips. In some lines, anthers are of normal length and project from the
corolla, although devoid of pollen. Female flowers of male sterile plants
appear normal and are fertile when pollinated.
A single male sterile cytoplasm, PET1, derived from H. petiolaris ssp.
petiolaris (Leclercq 1969) and the identification of dominant fertility
restoration genes (Enns et al. 1970; Kinman 1970; Vranceanu and Stoenescu
1971) advanced sunflower production from the use of open-pollinated
cultivars to hybrid production 35 years ago. This source of cytoplasmic
male sterility and a few fertility restoration genes, including the widely
used Rf 1 and Rf 2 genes, have been used exclusively for sunflower hybrid
production worldwide (Fick and Miller 1997).
Seventy CMS sources have been identified from progenies of crosses
between wild Helianthus accessions and cultivated lines, from wild
accessions grown in observation nurseries, or from induced mutation.
Fertility restoration genes have been reported for 34 CMS sources, and detailed
inheritance studies have been conducted for 19 of the 34 sources (Serieys
2002). A universal coding system was proposed by Serieys (1991) to
accommodate the ever increasing number of CMS sources. This 3-letter
coding abbreviation of the cytoplasm donor species and/or subspecies
followed by a numerical number starting from the number 1, depending on
 
Search WWH ::




Custom Search