PH13 improves soybean shade traits and enhances yield for high-density planting at high latitudes

Shading in combination with extended photoperiods can cause exaggerated stem elongation (ESE) in soybean, leading to lodging and reduced yields when planted at high-density in high-latitude regions. However, the genetic basis of plant height in adaptation to these regions remains unclear. Here, through a genome-wide association study, we identify a plant height regulating gene on chromosome 13 ( PH13 ) encoding a WD40 protein with three main haplotypes in natural populations. We find that an insertion of a Ty1/Copia -like retrotransposon in the haplotype 3 leads to a truncated PH13 H3 with reduced interaction with GmCOP1s, resulting in accumulation of STF1/2, and reduced plant height. In addition, PH13 H3 allele has been strongly selected for genetic improvement at high latitudes. Deletion of both PH13 and its paralogue PHP can prevent shade-induced ESE and allow high-density planting. This study provides insights into the mechanism of shade-resistance and offers potential solutions for breeding high-yielding soybean cultivar for high-latitude regions. How plant height is adaptive to high latitudes and high density planting is unclear. Here, the authors report a retrotransposon insertion in a WD40 protein encoding gene PH13 affects its interaction with GmCOP1s and increases the abundance of STF1/2, leading to reduced soybean height and increased shade resistance.