PREBREEDING OF MAIZE TRADITIONAL FARMERS¿ VARIETIES AND THEIR BIOFORTIFICATION FOR FOOD SAFETY AND SECURITY.

Maize is the main cereal grain cultivated worldwide (Zea mays L. ssp. mays), and alone is responsible for providing 15% of the protein and 20% of the calories in the human diet supplying an energy density of 365 Kcal/100 g. Maize is a good source of starch and protein; it also provides lipids, macronutrients, micronutrients and fiber. Maize has a matrix rich in organic compounds and minerals with potential benefits to health. Human nutrition remains one of the main uses, being a staple food for poor populations and determining the selection of varieties for producing many typical dishes such as polenta in Italy and pap in South Africa. Maize still represents a staple food for many populations: maize tortillas provide about 50%-65% of human energy intake in Peru, Bolivia, and in rural areas of Mexico; in Africa are located 16 among the 22 countries in which corn represents the main source of energy in the diet. In Sub-Saharian countries, maize consumption is comparable to that of rice in Asia. In poor regions of the word nutrient deficiency (Zn, Fe and vitamin A) has a relevant role in child and adult mortality. In particular vitamin A deficiency ranks in top position among factors contributing to blindness, and affect cognitive development in children Thus, while productivity remains the major target for breeders, focusing on grain quality, could be reduced deficiencies of some minerals and provitamin A increasing the concentration of functional compounds and the nutritional value in particular for poor populations that use maize as staple food. Bio-fortification programs could be useful for rich countries where in the last years the attention for nutrigenomic and the demand of gluten-free, vegetarian, vegan and high nutritional value food is growing obtaining products with added value; but mainly for the poor countries where the main goal is to reduce the target population having low intake of these fundamental nutrients. Bio-fortification can use as source of genetic variability landraces and traditional farmers’ varieties. These important genetic sources with their inter-genotypic balance are well-known to have natural variation in important nutraceuticals, which has been lost in several years during the breeding of modern cultivars having a superior nutritional value. Furthermore, in low input system, they present yield stability in response to biotic and a-biotic stresses. In these cases, participatory breeding, involving gene banks and farmers, can have a significant and positive influence ameliorating some negative consequences of modern agriculture and conventional breeding. In order to explore and identify the genetic variability of Italian and European landraces and traditional farmers varieties and to use these in breeding programs, we performed a pre-breeding activity in collaboration with CREA. With this pre-breeding activity we demonstrated the nutritional superiority of ancient varieties if compared with modern hybrids. In particular Spinato di Gandino is the best variety for milling properties and for oil, protein, and total phosphorus content; Storo is the best variety for calorific value and for carotenoids and free phosphorus content, Nero Spinoso is an interesting variety for nutrient amount in general and mainly for phlobaphenes presence. From these varieties we started a bio-fortification program aimed to obtain new synthesis populations with high nutritional value. In particular we focused on Nero Spinoso. Thanks to the high phlobaphenes content and the good nutritional value Nero Spinoso could be considered as functional foods, able to increase the amount of antioxidants introduced in the diet in fact their high antioxidant power suggests effects similar to the ones of the anthocyanins. Moreover these molecules are thought to have an important role in plant’s resistance against different pathogens and are probably involved in flavonoids antifungal activity: phlobaphenes and other flavonoids are thought to harden maize pericarp, acting as a physical barrier against fungal infection and reducing the mycelial progress from a seed to another. For this reason we decided to recover a P1 gene and we introgressed it in different genetic backgrounds of high performance varities finding that P1 could be a regulator gene that leads to an increase of the pericarp thickness, a decrease of fumonisins accumulation and an increase of phlobaphenes concentration in varieties with the same genetic background that are different only for this allele. Starting from here we can enhance the production and cultivation of corn varieties rich in phlobaphenes in areas characterized by a humid and rainy climate. Our pre-breeding activity was carried out also in South Africa where maize us a staple food for the population. There we characterized from the phenotypical and nutritional points of view one white and one yellow South African landrace maize cultivar obtained directly from the farmers in the rural region of Qwa-Qwa (Free State Province). Our data show that there are no nutritional reasons to prefer the white variety for human consumption, with the exception of the large size of the seeds, which make them particularly adapted for milling. In collaboration with the Vaal University of Technology we started a bio-fortification program using the best European varieties in order to increase the nutritional value of the white variety. We will try to improve protein, Fe and carotenoids amount, contributing in this way to tackle the problem of malnutrition in South African rural areas.