J. M. Crane

Genetic distance as a predictor of heterosis and hybrid performance within and between heterotic groups in sunflower

Abstract Heterosis is significant for seed yield and is one of the driving forces behind the hybrid seed industry in cultivated sunflower (Helianthus annuus L). Heterotic groups in sunflower, if any other than the female and male inbred-line groups exist, have not been well studied or described. The primary aims of this study were to assess the utility and validity of a series of proposed heterotic groups and estimate correlations between genetic distance, heterosis, and hybrid performance for seed yield in sunflower. Fortytwo female by male heterotic group (A × R) and 81 female by female heterotic group (A × B) single-cross hybrids were grown in Corvallis, Ore., and Casselton, N.D., in 1996 and 1997. Heterosis was significant for seed yield and plant height but not for seed oil concentration and days to flowering. Genetic distances were significantly correlated with hybrid seed yield when estimated from AFLP fingerprints (GD) (r = 0.63 for A × R and 0.79 for A × B hybrids), but not from coancestries (GC) (r = -0.02 for A × R and 0.54 for A × B hybrids). GD (R2 = 0.4) was a poor predictor of hybrid seed yield. The proposed heterotic groups in sunflower seem to have utility, but do not seem to be as strongly differentiated as those in corn (Zea mays L.). The highest-yielding hybrids were from the BC× RB heterotic pattern; however, several BC× BC hybrids (within-group hybrids) were among the top-yielding hybrids. The outstanding performance of certain BC× BC hybrids casts some doubt on the validity of the BC group. Substantial genetic diversity seems to be present within and between heterotic groups in sunflower.

Fatty acid diversity of Section Inflexae Limnanthes (meadowfoam)

Abstract Meadowfoam (Limnanthes ssp.) is a rich source of unique unsaturated long-chain fatty acids. The commercial crop is based on L. alba (Section Inflexae of the Limnanthaceae). We describe the fatty acid diversity of L. alba and other Section Inflexae taxa. The unsaturated fatty acid percentage for L. alba seed oil was 97.9%. Significant differences were found for 20:1Δ5, 22:1Δ5, 22:1Δ13, and 22:2Δ5Δ13 percentage among L. alba half-sib families. The percentage ranges for 20:1Δ5, 22:1Δ5, 22:1Δ13, and 22:2Δ5Δ13 were 57.6 to 68.8, 2.3 to 6.3, 6.5 to 15.6, and 7.9 to 27.7, respectively. Fatty acid phenotypes different from L. alba were not found within the secondary and tertiary gene pools of L. alba. The heritabilities for 20:1Δ5, 22:1Δ5, 22:1Δ13, and 22:2Δ5Δ13 within L. alba were 0.73, 0.78, 0.97, and 0.93, respectively. Strong associations were found between S0 and S1 fatty acid phenotypes. S1 lines were developed with 68.1% 20:1Δ5, 6.9% 22:1Δ5, 23.5% 22:1Δ13, and 23.4% 22:2Δ5Δ13. Induced mutations are needed to develop more extreme phenotypes than those based on natural variants within Section Inflexae.

Papaver bracteatum, potential commercial source of codeine

Papaver bracteatum, native to Iran and southern Russia, has been grown successfully in many countries. Research in the northwest United States has confirmed the potential for its commercial production as a source of the alkaloid thebaine. Potential for the chemical conversion of thebaine into codeine, one of man’s most widely used alkaloidal medicinal agents, is reviewed. Economic and social advantages of growing this species over opium poppy (Papaver somniferum) are discussed. The value of the seed oil for cooking and industrial use is considered.

The development of a genetic map for meadowfoam comprised of amplified fragment length polymorphisms

Abstract  Limnanthes alba Benth. (meadowfoam), a diploid (x=5) winter annual, produces novel very long-chain seed oils (C20 and C22) with less than 2% saturated fatty acids. The first genetic map of meadowfoam, a recently domesticated species, is described herein. Two phenotypically diverse inbred lines, OMF40–11 (L. alba ssp. alba) and OMF64 (L. alba ssp. versicolor), were screened for amplified fragment length polymorphisms (AFLPs) using 16 primer combinations. Twenty three percent of the AFLP bands (415 out of 1,801) were polymorphic between OMF40–11 and OMF64. One hundred (OMF40–11×OMF64)×OMF64 BC1 progeny were genotyped for 107 polymorphic AFLP markers produced by nine AFLP primer combinations. One hundred and three AFLP loci amalgamated into five linkage groups with 14 to 28 loci per linkage group (four loci segregated independently). The map was 698.5-cM long with a mean interlocus spacing of 6.7 cM and no dense clustering of loci. The segregation ratios for 25 loci (23.2%) were significantly distorted. Twenty one of the distorted loci (84%) had an excess of L. alba ssp. versicolor (recurrent parent) alleles. The distorted loci, apart from one locus on linkage group 4, were distally clustered on both ends of linkage groups 1, 4 and 5. The development of the map was facilitated by the small chromosome number, an abundance of restriction site polymorphisms between the two subspecies (23%), and a high multiplex ratio of the AFLP markers (112 per primer combination).

A dominant gene decreases erucic and increases dienoic acid in the seed oils of meadowfoam subspecies

Meadowfoam (Limnanthes alba Benth.) seed oil is a source of erucic acid (22:1 Δ13) and novel very long-chain fatty acids. The fatty acid profiles of L. alba subspecies are distinctly different. L. alba ssp. versicolor produces significantly mere erucic acid and significantly less dienoic acid (22:2) than L. alba ssp. alba, The L. alba ssp. alba profile is the standard for certain meadowfoam oil markets. Because changes in the profile could affect meadowfoam oil markets, we completed a study to elucidate the genetics of erucic and dienoic acid content differences in the subspecies. The fatty acid contents of F 2 and F 3 progeny from an L. alba ssp. alba × L. alba ssp. versicolor (P 1 x P 2 ) cross were assayed by gas chromatography. P 1 produced 81 g kg -1 erucic acid and 297 g kg -1 dienoic acid, whereas P 2 produced 242 g kg -1 erucic acid and 86 g kg 1 dienoic acid. There were two non-overlapping erucic by dienoic add phenotypic classes among 100 F 2 progeny. The phenotypic distribution (79:21) was not significantly different from 3:1 (P = 0.48); thus, these progeny segregated for a dominant gene. This was verified by F 3 progeny tests. Unless markets can tolerate the range of fatty acid compositions found in L. alba germplasm, cultivars with the L. alba ssp. alba fatty acid profile must be developed.