Academician Hanzhong Wang’s team revealed the new regulatory mechanism for yield traits in rapeseed (Brassica napus L.)

Recently, academician Hanzhong Wang, the chief scientist for the innovation team of rapeseed genetic improvement in OCRI-CAAS, has guided his team members to reveal a new maternal regulatory mechanism for seed weight in rapeseed. This new finding has been published in the Plant Biotechnology Journal, which provided new theory and approach for the genetic improvement of yield traits.

Seed weight is an important component of yield in rapeseed. The previous research on yield is concentrated on seed itself, such as embryo and endosperm, and the relative contribution and regulatory mechanism of mother plant in determining seed weight is unknown. For this purpose, his team conducted an ingenious (hand emasculation and self- and cross-pollination on the same mother plant) genetic analysis using the representative extremely large- and small-seed accessions chosen from the core germplasm. The results showed that maternal genotype accounted for an average 93% of the variation of seed weight in rapeseed, playing a predominant role, which overturned the previous  understanding of this issue. On this basis, a systematic (including genetic, morphological, cytological, physio-biochemical and molecular) comparative study was conducted, using the extremely large and small-seed recombinant inbred lines derived from an elite sequenced cultivar Zhongshuang 11 and No.73290. They found that these lines carried two major quantitative trait loci that regulated the expression of downstream genes related to pod development, which affected pod length and photosynthetic area, photosynthate accumulation in the pod wall and its transport and storage in seed, and finally influenced seed filling, size and weight.

For the main crops such as wheat, rice and maize, leaf is the major source of photosynthate; whereas in the rapeseed, pod wall is the major source of photosynthate for seed filling and weight formation during its later developmental stage. Therefore, this research has opened a new research field for seed weight in plants. This finding was another important original work of this team since they firstly reported that pod all photosynthetic rate maternally regulated seed oil content in 2012, which enriched the maternal regulation theory of the main seed traits in plants.