Mario Baldini

Evaluation of genetic diversity between toxic and non toxic Jatropha curcas L. accessions using a set of simple sequence repeat (SSR) markers

Scepticism about Jatropha as a competitive biofuel feedstock especially on marginal soils has been growing; in fact, the jatropha-biofuel chain is risky economically and often financially unfeasible without significant government subsidies under these conditions. A valorization of the by-products and in particular of the extruded seed cake (about 70% (w/w) of the processed seed), as animal feed, currently prevented by the presence of phorbol esters (PE) toxins, could contribute to a significant improvement in the economic sustainability of the crop. Strategies for breeding improved varieties could be accelerated by DNA-based molecular marker technology. Wild Mexican accessions and accessions from other parts of the world (South America and Africa) were analyzed by 40 simple sequence repeat (SSR) markers. SSR primers were chosen on the grounds of their Tm, length, degree of polymorphism and specificity for toxic trait. The genetic study pointed out a high degree of similarity both within and among the non Mexican accessions. The Mexican accessions proved to be non toxic and genetically differentiated forming a well separated cluster from out of Mexico accessions. Some polymorphic loci were close correlated with the character toxicity and useful, once validated their association in segregating populations for Marker Assisted Selection (MAS). Keywords : Jatropha curcas , genetic variability, molecular markers, non-toxic accession, phorbol esters, simple sequence repeat (SSR) genotyping African Journal of Biotechnology Vol. 12(3), pp. 265-274

Kernel oil content and oil composition in walnut (Juglans regia L.) accessions from North Eastern Italy

BACKGROUND Walnut oil use is currently limited by its poor oxidative stability due to the high percentage of polyunsaturated fatty acids. Modifying the oil composition may be a goal in walnut breeding to increase interest in this crop. Exploring natural variability and identifying the main environmental factors affecting oil quality are necessary in crop selection. Therefore 190 wild accessions were collected and evaluated during 2013 and 2014 for oil content and its fatty acid profile and compared with five commercial cultivars as references. RESULTS High variation in kernel oil content and fatty acid composition was found in the native walnut. Kernel oil content ranged from 54.2 to 72.2% (w/w). The major fatty acids were linoleic (range 46.9-68.6%), oleic (10.0-25.1%), linolenic (6.9-17.6%), palmitic (3.9-11.4%) and stearic (1.1-5.2%) acids. Some accessions had oil with a fatty acid ratio very different from the reference commercial cultivars, especially the oleic acid/polyunsaturated fatty acid (PUFA) ratio. A significant linear relationship and positive correlation between the daily minimum temperature and oleic acid content was observed in the wild walnuts. CONCLUSION The wide variation in fatty acid content and composition allows superior accessions to be selected for diffusion among growers. A suitable strategy would be to make a selection against PUFA content rather than just for high oleic acid. In addition, the selected high oleic accessions, before being utilized per se or as donor parents in breeding programs, have to demonstrate they are not adversely affected by the environment.