QTL mapping of seven agronomic traits in maize based on the introgression lines

Abstract

Maize ( Zea mays L.) is an important crop with great nutrition, fodder and energy values. The yield of maize is dependent on the integration and coordination of a lot of agronomic traits, such as plant height, ear length, grain weight per spike and others, which are controlled by micro-effects of multiple genes. The objective of this study was to identify genes related to agronomic traits in maize inbred line PHB1M and to investigate the correlation between those genes and yield-related traits. An introgression line was constructed using tetra-287 as a donor to improve the backbone maize inbred lines and create new breeding resources. The progenies were grown and evaluated in both Helin and Hohhot, Inner Mongolia of China. With 70 pairs of SSR and 64 pairs of SRAP primers, the constructed introgression materials were genotyped. As a result, a total of 793 polymorphic loci were obtained locating 10 linkage groups. A linkage map was then constructed with a length of 1917.2 cM. By using MQM mapping method, a total of 100 QTLs were identified in both locations, which distributed on 9 linkage groups except the 10th linkage group. Fifty QTLs were detected in single environment, with LOD values ranged from 3.20 to 9.12, and contribution rates ranged from 2.2% to 35.2%. Among the 100 QTLs, 23 for plant height, 16 for ears height, 22 for number of leaves, 10 for ear length, 16 for shafts diameter, 4 for ear rows, and 9 for 100-grain weights were identified; Eight genes controlling 5 traits were consistently expressed from plant of both locations, including 2 QTLs controlling plant height ( qPH1-5 and qPH2-6 , qPH1-6 and qPH2-7 ), 1 for ear height ( qEP1-2 and qEP2-1 ), 1 for leaf number( qLN1-10 and qLN2-4 ), 2 for ear length ( qEL1-2 and qEL2-1 , qEL1-4 and qEL2-4 ), and 2 for shafts diameter( qSD1-3 and qSD2-2 , qSD1-8 and qSD2-5 ). Three QTLs expressed stably for plant height and ear height, and 14 enriched QTL regions were found on 6 linkage groups. This research provided theoretical support for gene cloning and marker-assisted maize breeding.