A distal SNP downstream to SHOOT APICAL MERISTEM ENLARGER1 regulates its expression to promote branch and silique numbers in rapeseed
Rapeseed (Brassica napus) is an important crop providing vegetable oil. Yield is positively correlated with increased numbers of seeds, siliques, and branches. In a previous study, a rapeseed germplasm having normal branch and silique numbers was crossed with another germplasm having higher branch and silique numbers to identify the causal quantitative trait locus, NIL. In the current study by Zhang et al., the authors show that the NILDD allele is related to normal branch and silique numbers while the NILdd allele is related to higher branch and silique numbers. Both alleles carry a Brassicaceae-specific gene, SHOOT APICAL MERISTEM ENLARGER1 (SAME1), which encodes a transcription factor. SAME1 is highly expressed in the shoot apical meristem (SAM) of rapeseed plants carrying the NILdd allele but barely expressed in those carrying the NILDD allele. SAME1 transcriptionally represses a negative regulator of SAM growth, thus promoting SAM growth in plants carrying the NILdd allele. Sequence analysis of NILDD and NILdd alleles reveals a single nucleotide polymorphism (SNP) 1.4kb downstream of SAME1. Using a luciferase reporter assay, the authors show that the SNP regulates SAME1 expression, although the mechanism remains unclear. (Summary by Yee-Shan Ku @Yee-Shan Ku) Plant Biotechnol. J. 10.1111/pbi.70500
