Genome-wide association study identifies genetic factors for grain filling rate and grain drying rate in maize

Grain filling rate (GFR) and grain drying rate (GDR) are important for maize final yield determination and adaptability. To identify marker-trait associations and candidate genes, a diverse maize population consisting of 290 inbred lines was used and a genome-wide association study was conducted with 201 SSR markers. GFR and GDR of all stages showed broad phenotypic variations and a total of 33 and 20 excellent lines were selected out for GFR and GDR in the five heterosis groups. Furthermore, 50 significant associations were detected within 30 different markers, of which, 33 and 17 of all associations were respectively corresponding to GFR and GDR of all periods in all environments. Interestingly, two candidate genes of sus1 and pdk1 functioning in starch synthesis were possibly linked to two detected markers of umc1771 and mmc0241 for GFR. Additionally, wx1 matching phi027 for GFR at 20 days encoding a protein was also predicted to relate to starch synthesis. Therefore, those results provide useful information for our understanding on genetic basis in the control of GFR and GDR as well as tools for marker-assisted selection in maize breeding.