Genetic improvement of the pol CMS restorer 621R of Brassica napus L. in boron-efficiency by molecular marker-assisted selection.

Rapeseed is one of the crops that require the highest amount of boron, and additional application of boron fertilizer is necessary for production to prevent significant reduction in yield. To enhance the utilization efficiency of boron in rapeseed, we employed 2016-XFSB as a donor parent, which carries the superior allele Bna. A03NIP5;1, and used 621R as the recurrent parent. Through MAS-aided backcrossing, we successfully introduced the superior allele Bna.A03NIP5;1 into 621R and developed a near-isogenic line named 621^RNIP5;1A3. Subsequently, new hybrids were generated by crossing both 621R and 621^RNIP5;1A3 with a nuclear male sterility line RG430A. Hydroponic experiments and various soil cultivation experiments were conducted to evaluate agronomic traits performance of both 621R and 621RNIP5;1A3 lines as well as their hybrids. The results demonstrated a significant improvement in boron utilization efficiency for both 621^RNIP5;1A3 line and its hybrid counterparts. Moreover, these improved materials exhibited notable advantages in biomass accumulation, plant height development, silique length extension, number of grains per silique incrementation, and seed weight enhancement. The findings from this study provide valuable insights for breeding boron-efficient varieties in Brassica napus. [ABSTRACT FROM AUTHOR]