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SUMMARY The Pervenets mutation raises the oleic acid content (OAC) from about 25% (LO linoleic sunflower) to over 75% (HO sunflower) in sunflower seed oil whatever the genetic backgrounds of the genotypes: fixed mutant lines, hybrid between fixed mutant lines and, surprisingly, both direction cross hybrids between high oleic × linoleic and linoleic × high oleic lines. Here we develop the methodology to point out the coincidence between the mutation and the oleate-desaturase locus. The mutation function is modeled to explain the phenotype. A series of sunflower genotypes developing embryos between 12 and 24 days after pollination without or carrying the Pervenets mutation was used to compare oleate-desaturase transcript accumulation. This revealed the presence and absence of the transcript, in normal LO and Pervenets HO embryos, respectively, whereas stearate-desaturase transcript accumulation was equivalent in both types. The RFLP approach using oleate-desaturase cDNA as a probe has revealed that in comparison with the linoleic sunflower, those carrying Pervenets mutation displayed, besides a common 5.8 kb EcoRI fragment, an extra 8 kb EcoRI fragment and, with HindIII, the shift from 8 kb to 16 kb of a HindIII fragment. The common 5.8 kb EcoRI fragment to Pervenets and normal sunflower carries an oleate-desaturase gene. The insertion unique to the sunflower carrying Pervenets mutation has to carry oleate-desaturase sequences. The genetic studies of this mutation have lead to contradictory results in the inheritance pattern of the HO trait due to variable mutation expression and several genetic factors affecting the HO level. Thus, it appeared important to study the inheritance in a set of recombinant inbred lines. Moreover, we pointed out that the presence of the mutation is not sufficient to induce the HO phenotype since a suppressor of the mutation “supole” may mask the HO trait. The supole allele is revealed in half of the HO RI lines, and consequently its accurate mapping is difficult. Thus conjunction of the molecular and genetic methods and of material construction was required to solve this problem and to provide efficient tools to breed HO sunflower.

SUMMARY The effect of osmotic and water stresses on various morphological traits was studied in eight experimental varieties of sunflower bred for Moroccan conditions or issued from interspecific hybridization with H.argophyllus or H.debilis. Seed yield of the same genotypes was also evaluated under rainfed and irrigated field conditions. Shoot and root growth were significantly reduced by osmotic stress (-0.6 and -1.0 MPa) induced with polyethylene glycol (PEG 6000). Considerable genotype variation was expressed for all traits. Significant genotype by stress interaction was observed for root dry weight and volume as well as seed yield. The morphological traits were not related to seed yield in the correlation and principal component analyses. Four genotypes issued from introgression with H.argophyllus were grouped and distinct from other genotypes according to hierarchical ascending classification. One genotype issued from introgression with H.debilis and three non-introgressed sunflower varieties were found to be very distinct from each other and from those introgressed with H.argophyllus.

SUMMARY This work aims to clone the genomic region of the sunflower genome that may carry the Pervenets mutation causing high oleic content of seed oil. We previously reported that the oleHOS allele at the oleate-desaturase locus (oleHL) carries or is genetically closely linked to Pervenets mutation. We pointed out that the fragments that border the 5.8 kb EcoRI fragments carry the Pervenets mutation. The oleHOS reference physical map was constructed. It displays a common part made of the 5.8 kb EcoRI fragment, also present in oleLOR allele, and a specific region with the 7.9 kb EcoRI fragment, also carrying oleate-desaturase sequences. A genomic library was constructed in λfixII with an average insert size of 15 kb. Two millions clones were screened enabling to isolate clones from Group I, which were entirely sequenced and revealed carrying a gene for an oleate probably located in the RE. This corresponds to the invariant part of the oleHL locus. Two clones of Group II (11.1, 27.1) are overlapping but 11.1 is characterized by new specific restriction fragments and instability leading to a smear when probed with the oleate cDNA. Consequently, 11.1 sequence probably carries oleate repeated sequences that cause instability of the clone. The clone 11.1 is a good candidate to carry a part of the specific oleHOS allele, but due to its organization in repeats it is not yet sequenced. This organization leads to speculate on the mechanisms that could disturb oleate function in Pervenets [HOAC] genotypes.

SUMMARYAn experiment has been carried out in order to study the behaviour under mineral deficiency of three sunflower genotypes, a population variety (Oro 9) and two hybrids (Mirasol and Albena). Sunflower seedlings were submitted to five treatments: N deficiency (N0), P deficiency (P0), K deficiency (K0), N and K deficiency (N0K0) and a control. Plants were harvested when they reached 3-4 true pairs of leaves. Growth parameters measured (height, total leaf area, root length, root and shoot dry mater) were all significantly reduced by mineral deficiency. Leaf area was most reduced by N0 (-61%) and P0 (-56%). Total dry matter was most affected by N0 (-63%) and by N0K0 (-66%). Genotype comparisons showed that Oro 9 had the highest shoot dry matter while Albena had the lowest root dry matter. Effect of mineral deficiency on content and partitioning of N, P, K, Ca and Na was significant and varied according to treatments and among plant parts. Shoot dry weight was significantly correlated with root N content (r2=0.81) and root K content (r2=-0.61) for N0 and K0.

SUMMARYIn arid and semi arid areas, water is the most limiting factor of crop production. Germination is susceptible to water shortage. Experimentation was undertaken to study the effect of water stress on germination of seeds of three sunflower genotypes (Oro 9, Mirasol and Albena). Six PEG 6000 osmotic constraints were tested (0, -0.4, -0.6, -1, -1.2 and -1.6 MPa). Results showed no significant difference between germination percent of the control and -0.4 MPa treatment and between -0.8, -1 and -1.2 MPa treatments. Germination percent was most reduced at -1.6 MPa (-65%). Mean germination duration was also affected and the highest value was obtained for -1.6 MPa (4.95 days, related to an increase of 185%). Differences between genotypes were significant in the treatment at -1 MPa.