Identification of QTL and candidate genes involved in early seedling growth in rice via high-density genetic mapping and RNA-seq
Jing Yang,
Zhenhua Guo,
Lixin Luo,
Qiaoli Gao,
Wuming Xiao,
Jiafeng Wang,
Hui Wang,
Zhiqiang Chen,
Tao Guo
Affiliations
Jing Yang
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China
Zhenhua Guo
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China; Rice Research Institute of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154026, Heilongjiang, China
Lixin Luo
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China
Qiaoli Gao
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China
Wuming Xiao
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China
Jiafeng Wang
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China
Hui Wang
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China
Zhiqiang Chen
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China; Corresponding authors.
Tao Guo
National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangzhou 510642, Guangdong, China; Corresponding authors.
Early seedling vigor (ESV) is a major breeding target in rice, especially under direct seeding. To identify quantitative trait locus (QTL) affecting ESV, a recombinant inbred line population derived from a cross between 02428 and YZX, two cultivars differing in vigor during early seedling growth, was used for QTL analysis. Nine traits associated with ESV were examined using a high-density map. Of 16 additive loci identified, three were detected in two generations and thus considered stable. Four epistatic interactions were detected, one of which was repeated in two generations. Further analysis of the pyramiding effect of the three stable QTL showed that the phenotypic value could be effectively improved with an increasing number of QTL. These results were combined with results from our previous QTL analysis of the germination index. The lines G58 and G182 combined all the favourable alleles of all three stable QTL for ESV and three QTL for germination speed. These two lines showed rapid germination and strong ESV. A total of 37 candidate differentially expressed genes were obtained from the regions of the three stable QTL by analysis of the dynamic transcriptomic expression profile during the seedling growth period of the two parents. The QTL are targets for ESV breeding and the candidate genes await functional validation. This study provides a theoretical basis and a genetic resource for the breeding of direct-seeded rice.
