QTL mapping and candidate genes screening of photosynthesis-related traits in Brassica napus L. during seedling stage under aluminum stress.

Due to excessive soil acidification, aluminum in soil has become one of the main factors limiting crop growth and yield. In this study, a high generation of recombinant inbred line (RIL) population constructed from Brassica napus L. varieties Zhong-shuang 11 (ZS11) and 10D130 treated with 2400 µmol L^-1 aluminum solution was used as experimental materials. To explore the photosynthetic capacity and chlorophyll fluorescence related traits of rapeseed seedling stage under aluminum toxicity stress, we calculated their relative values (treatment/control) and mapped their QTLs, and screened suitable candidate genes according to the confidence interval of QTLs. The results showed that there was significantly correlation between photosynthetic capacity and chlorophyll fluorescence parameters, but there was no significant correlation between photosynthetic capacity and the chlorophyll fluorescence parameters. Relative P_n, relative G_s, relative C_i, relative Φ_PSII, relative F_v/F_o, relative F_v'/F_m', relative q_P, relative ETR, relative NPQ, and relative dry weight were investigated and QTLs mapping were analyzed. A total of 16 QTLs related to aluminum stress and photosynthesis were detected. The locus was located on chromosomes A03, A05, A06, A08, A09, A10, C02, and C09, respectively. LOD value was 2.05-3.18, and the phenotypic variation explained was 8.1%-12.3%. The confidence intervals of QTLs for relative Gs and relative F_v'/F_m', relative Φ_PSII and relative ETR were found completely overlap at 106.038--109.129 cM of chromosome A03, 145.355-167.417 cM of chromosome A06, respectively. 47 candidate genes that may be related to aluminum stress and photosynthesis were screened, involving organic acid secretion, metal ion transport, hormone regulation, initiation of antioxidant protection, chloroplast self-regulation, and phosphorus uptake regulation. This study lays the foundation for the function research of aluminum resistance and related photosynthetic genes and the breeding of aluminum tolerant and high photosynthetic efficiency rapeseed. [ABSTRACT FROM AUTHOR]