Brassinosteroid and gibberellin control of seedling traits in maize (Zea mays L.)

- Brassinoteroids and gibberellins were found to control seedling traits such as mesocotyl length in maize.
- Seedling stage brassinosteroid and gibberellin inhibitor response was found to be correlated with field traits flowering time and yield.
- A WRKY candidate gene GRMZM2G013391 was identified to regulate GA pathway in maize, consistent with rice studies that WRKY gene encodes a transcriptional repressor of the gibberellin signaling pathway.

In this study, we established two doubled haploid (DH) libraries with a total of 207 DH lines. We applied BR and GA inhibitors to all DH lines at seedling stage and measured seedling BR and GA inhibitor responses. Moreover, we evaluated field traits for each DH line (untreated). We conducted genome-wide association studies (GWAS) with 62,049 genome wide SNPs to explore the genetic control of seedling traits by BR and GA. In addition, we correlate seedling stage hormone inhibitor response with field traits. Large variation for BR and GA inhibitor response and field traits was observed across these DH lines. Seedling stage BR and GA inhibitor response was significantly correlate with yield and flowering time. Using three different GWAS approaches to balance false positive/negatives, multiple SNPs were discovered to be significantly associated with BR/GA inhibitor responses with some localized within gene models. SNPs from gene model GRMZM2G013391 were associated with GA inhibitor response across all three GWAS models. This gene is expressed in roots and shoots and was shown to regulate GA signaling. These results show that BRs and GAs have a great impact for controlling seedling growth. Gene models from GWAS results could be targets for seeding traits improvement.