Abstract

Rapeseed is one popular oil crop dominantly contributing to the worldwide edible oil production. To reasonably contract individual plant size and compact plant architecture can facilitate rapeseed dense planting, thus enhancing the seed yield per unit area. The petiole links the leaflet to its appendiculate stem and plays essential roles in supporting the whole leaf and nutrient transportation. The length of petioles primarily determines leaf architecture and facilitates photosynthesis of plant populations in the field. Petiole length demonstrates great variations in rapeseed natural population, while its genetic mechanisms remain largely unknown. Here, an F 2 population was constructed from two parents whose petiole length was significantly different, and one remarkable locus on chromosome C02 ( qPL.C02 ) was identified for petiole length by Bulked Segregant Analysis (BSA). Based on the phenotypic investigation of the recombinants of a total of 2,315 F 2 and BC 1 F 2 plants under field conditions, the primary 4.77 Mb region (ZS11.v0_C02: 58.21-62.98 Mb) was narrowed down to a 299 kb region by stepwise mapping analysis. The qPL.C02 determined petiole length at the early leaf developing stage rather than the subsequent growth period. Two practical KASP markers anchoring the fine-mapped qPL.C02 intervals were developed and facilitated the introgression of the qPL.C02 short-petiole genotype into one elite variety, ZS11. The ZS11 qPL.C02 SP introgressed lines exhibited comparatively shorter petioles and demonstrated a considerable yield-increasing potential at both conventional and dense planting conditions in the field. Sequence variation and transcript expression analysis identified BnaC02G0511100ZS , encoding an ethylene-responsive factor, as the candidate gene for qPL.C02 . This study demonstrated a primary case study for genetic regulation of rapeseed petiole development, providing one reliable and effective means for rapeseed dense-planting breeding.