Identification of QTL-s for drought tolerance in maize, II: Yield and yield components

Abstract

Grain yield is the primary trait of interest in maize breeding programs. Worldwide, drought is the most pervasive limitation to the achievement of yield potential in maize. Drought tolerance of maize has been considerably improved through conventional breeding. Traditional breeding methods have numerous limitations, so development of new molecular genetics techniques could help in elucidation of genetic basis of drought tolerance .In order to map QTLs underlying yield and yield components under drought 116 F3 families of DTP79xB73 cross were evaluated in the field trials. Phenotypic correlations calculated using Pearson's coefficients were high and significant. QTL detection was performed using composite interval mapping option in WinQTL Cartographer v 2.5. Over all nine traits 45 QTLs were detected: five for grain yield per plant and 40 for eight yield components. These QTLs were distributed on all chromosomes except on chromosome 9. Percent of phenotypic variability determined for the identified QTLs for all the traits was in the range from 27.46 to 95.85%. Different types of gene action were found for the QTLs identified for analyzed traits.

Prinos je najvažnije svojstvo u programima oplemenjivanja kukuruza, a suša je glavni ograničavajući faktor u postizanju optimalnog prinosa. Značajno poboljšanje tolerantnosti na sušu kod kukuruza ostvareno je metodama konvencionalnog oplemenjivanja. Međutim, tradicionalne metode oplemenjivanja imaju brojna ograničenja, pa se zahvaljujući razvoju novih metoda molekularne genetike može postići napredak u rasvetljavanju genetičke osnove tolerantnosti na sušu. U cilju mapiranja QTL-ova za prinos i komponente prinosa kod kukuruza u uslovima suše izvršeno je fenotipsko ocenjivanje 116 F3 familija ukrštanja DTP79xB73 u polju. Fenotipske korelacije između ispitivanih svojstava su izračunate pomoću Pirsonovog koeficijenta i bile su visoke i značajne. Za identifikaciju QTL-ova korišćena je composite interval mapping opcija u programu WinQTL Cartographer v 2.5. Detektovano je ukupno 45 QTL-ova za devet analiziranih svojstava: pet za prinos i 40 za osam komponenti prinosa. QTL-ovi su detektovani na svim hromozomima izuzev na hromozomu 9. Procent fenotipske varijabilnosti identifikovan za sve QTL-ove za sva ispitivana svojstva bio je u opsegu od 27.46 do 95.85%. Različiti tipovi genskih efekata detektovani su za različite QTL-ove za analizirana svojstva.