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Seed oil content and composition are important considerations in sunflower breeding programmes because these traits are related to oil quality. They are complex traits that are determined by genotypic factors and environmental conditions. The objective of this study was to estimate the interaction between genotype and environment for oil content and major fatty contents in traditional, high and mid-oleic sunflower genotypes and to identify stable genotypes. Combined analyses of variance of oil, oleic and linoleic acid content of 16 genotypes tested over six locations showed highly significant mean squares for genotype, environment and the interaction between them. On average the mid-oleic and standard genotypes had similar oil contents, but the high oleic genotypes had lower oil contents than the standard genotypes. Stability analyses indicated that one standard, one high oleic and one mid-oleic genotype were relatively stable with average to above average oil content. One high oleic genotype was stable across locations with an oleic acid content of above 80 %. The unstable high oleic acid genotypes that showed variation for oleic acid content across locations may be a consequence of location, temperature and rainfall effects. With adequate location and planting dates, high and mid-oleic hybrids could be produced with oil that meets the oil quality standards. [ABSTRACT FROM AUTHOR]

Safflower ( Carthamus tinctorius L.) DNA marker resources are currently very limited. The objective of this study was to determine the feasibility of transferring non-genic microsatellite (SSR) markers and gene-based markers, including intron fragment length polymorphism (IFLP) and resistance gene candidates (RGC)-based markers from sunflower ( Helianthus annuus L.) to safflower, both species belonging to the Asteraceae family. Cross-species amplification of 119 non-genic SSRs, 48 IFLPs, and 19 RGC-based sunflower markers in 22 lines and germplasm accessions of safflower was evaluated. Additionally, 69 EST-SSR markers previously reported to amplify in safflower were tested. The results showed that 17.6% of the non-genic SSR, 56.2% of the IFLP, and 73.7% of the RGC-based markers were transferable to safflower. The percentage of transferable markers showing polymorphic loci was 66.6% for non-genic SSR, 70.6% for EST-SSR, 55.5% for IFLP, and 71.4% for RGC-based markers. The highest polymorphism levels were found for non-genic SSR. The average number of alleles per polymorphic locus and mean heterozygosity values were 2.9 and 0.46, respectively, for non-genic SSR, 2.2 and 0.35 for EST-SSR, 2.1 and 0.24 for IFLP, and 2.0 and 0.34 for RGC-based markers. The results of this study revealed a low rate of transferability for non-genic SSR sunflower markers and a better rate of transferability for IFLP and RGC-based markers. Transferable genic and non-genic sunflower markers can have utility for trait and comparative mapping studies in safflower. [ABSTRACT FROM AUTHOR]

The content of coumarins, as probable phytoalexins, was analysed in four sunflower genotypes that ranged in responses to head rot from highly susceptible to highly resistant. Low levels of all coumarins (scopolin, scopoletin and ayapin) were detected in the three most susceptible genotypes irrespective of time after inoculation. However, in the resistant genotype there was a clear time-dependent disease-induced increase of all coumarins that reached a maximum after 10–14 days. Detailed comparison of the most susceptible and the resistant genotype showed that in the resistant but not the susceptible, scopoletin peroxidase activity increased during the course of the experiment. Results confirmed a clear negative correlation between coumarin content and disease symptoms and in particular for scopolin. Furthermore we show for the first time that scopolin is inhibitory to Sclerotinia at similar doses to scopoletin. As scopolin is known to be less phytotoxic than ayapin and scopoletin, its accumulation may well confer head rot resistance with minimal plant damage and might be one of the bases for resistance to Sclerotinia. [ABSTRACT FROM AUTHOR]

Disease symptoms and total soluble phenolics content have been analysed in four sunflower (Helianthus annuus L.) lines with different resistance levels (from highly susceptible to resistant) to head rot caused by Sclerotinia sclerotiorum (Lib.) de Bary. At the beginning of the flowering stage, capitula were inoculated by spraying with a water suspension of ascospores, and disease symptoms were evaluated from day 6 to day 14 after inoculation. The most susceptible genotypes showed all their ovaries to be necrosed and abundant lesions in corollas, bracts and receptacle. In the resistant line, the ovary and corolla were only partially necrosed with no symptoms in the bracts or the receptacle. Total soluble phenolics were extracted and quantified from different parts of the capitulum in both inoculated and non-inoculated plants. The amount of phenolic compounds depended on the sunflower line, the time after inoculation, and the tissue. Higher constitutive and induced phenolic content as well as phenylalanine ammonia-lyase activity were present in the most resistant line, these differences correlated with the absence/presence of disease symptoms. [ABSTRACT FROM AUTHOR]

The definition of a suitable breeding strategy in drought-prone environments is an important task for sunflower breeders. To achieve this task, reliable information on heritability and gene effects on yield and related traits under these conditions is necessary. Thirty six sunflower hybrids were produced by factorial cross of six male-sterile and six restorer lines. Parents and their hybrids were evaluated in eight environments. Six environments consisted of two adjacent trials in the experimental area, the first under irrigation and the second under dryland conditions, during 1987, 1988 and 1992. The other environments were: one early planting trial in dryland conditions, conducted during 1987, and a winter trial planted in January during 1988. Estimates of female variance (σf) were significant for seeds per head, seed weight, head sterile center, days to blooming and oil content. Female × male interactions (σ2 fm) were significant for all characters except harvest index and index of susceptibility to drought. Estimates of narrow sense heritabilities, calculated with information from analyses combined across environments, were 0.65 for yield, 0.80 for seeds per head, 0.84 for seed weight, 0.81 for head diameter, 0.60 for sterile head center, 0.72 for oil content, 0.61 for harvest index, 0.72 for biomass, 0.94 for days to bloom, and 0.42 for drought susceptibility index. Heritability estimates for individual environments showed more variation for yield than for other traits. Estimates for heritability of canopy temperature were high (0.68–0.79). Rainfed yield was positively correlated with yield components and negatively correlated with canopy temperature and susceptibility index. It is concluded that an efficient breeding strategy for sunflower under moderate drought-stressed conditions is the simultaneous selection for seed yield in both rainfed and irrigated environments together with selection for canopy temperature and stem diameter. [ABSTRACT FROM AUTHOR]