Approaches in breeding for high quality protein maize

Maize is the principal crop and major staple food in the most African and South American countries. The main problem in human nutrition in developing countries, and in livestock feed in developed countries, is insufficient production and poor quality of cereal proteins. In the case of maize, due to the very low content of essential amino acids lysine and tryptophan in grain endosperm, biological value is very low, which is main limiting factor of common maize in human nutrition and feeding of monogastric animals. Quality protein maize (QPM) can help in solving of this problem. Maize production also faces serious constraints caused by agro-ecological conditions and poor socio-economic situation. To alleviate the effect of the constraints, selected genotypes with more desirable traits and appropriate field-plot techniques to create multiple-stress conditions, were used. It was found that, in downy mildew nursery distance up to 35 m from spreader plot is providing sufficient down load of spores for plant infection, provided that the testing breeding materials are planted towards to down-stream direction of the dominant wind. Using these breeding approaches large number of early, white and flint synthetics, composites and inbred lines were created with resistance or tolerance to downy mildew (DMR), maize streak virus (SR) and drought (DT). Created genotypes exhibited very good kernel modification and yield potential under low and normal inputs. In the case of synthetics and composites, besides tolerance to multiple stress factors, they were competing in yield with local QPM and normal maize checks. In the case of created inbred lines high combining ability was exhibited both in non-conventional and conventional maize hybrids. Trial data revealed that in the most cases the best entries were over-yielding the best checks

Značaj genetičkih resursa iz različitih geografskih i klimatskih regiona u simultanom oplemenjivanju kukuruza na visok kvalitet proteina (VKP) i tolerantnost na stres

Due to the low biological value of proteins of common maize, it was reinitiated breeding for high protein quality maize (HQPM) using three genetic systems, namely: opaque-2 gene, endosperm modifier genes and enhancer genes, which are increasing lysine and tryptophan content in opaque-2 background In order to alleviate effect of abiotic and biotic stress factors, the genotypes with tolerance to those factors were included. Genetic resources originating from North, Central and South America, then West, Central and Southern Africa and gene bank of Maize Research Institute 'Zemun Polje' were used. Combining breeding approaches in selection of genetic resources, field plot techniques and laboratory analysis, it was created large number of early QPM varieties, inbred lines and hybrids with modified endosperm and high yield potential under poor and good growing conditions. Created lines exhibited high combining ability in conventional and non-conventional hybrids. Yield trials showed that QPM hybrids are competing with commercial hybrids of common maize.Zbog niske biološke vrednosti proteina zrna standardnog tipa kukuruza se pristupilo stvaranju sorata i linija kukuruza visokog kvaliteta proteina (VKP) korišćenjem tri genetička sistema: opaque-2 gena, gena modifikatora endosperma i gena enhansera koji povećavaju sadržaj lizina i triptofana u opaque-2 osnovi. Da bi se istovremeno ublažilo i delovanje abiotskih i biotskih faktora stresa uključeni su i genotipovi sa tolerantnošću na ove faktore. Korišćeni su genetički resursi poreklom iz Severne, Centralne i Južne Amerike, zatim Zapadne, Centralne i Južne Afrike i resursi iz banke gena Instituta za kukuruz 'Zemun polje'. Kombinovanjem selekcionih pristupa u izboru genetičkih resursa, tehnika u poljskim i laboratorijskim uslovima stvoren je veliki broj ranih sorata, inbred linija i hibrida VKP, modifikikovanog endosperma i visokog potencijala rodnosti pod lošim i normalnim uslovima gajenja. Takođe, stvorene inbred linije su ispoljile visoku kombinacionu sposobnost u nekonvencionalnim i konvencionalnim hibridima. Poljski ogledi su pokazali da VKP hibridi konkurišu po prinosu najboljim komercijalnim hibridima standardnog tipa kukuruza