Soybean (Glycine max) is an essential economic crop and provides 28.7% of the vegetable oil and 70.7% of the protein meal worldwide. Seed weight is usually associated with seed size and is one of the important agronomic traits that determine yield. However, understanding of the genetic and molecular basis of soybean seed size/weight control is very limited.
Research group of Prof. ZHANG Jinsong, from the Institute of Genetics and Developmental Biology (IGDB), Chinese Academy of Sciences (CAS), recently reported that the GmJAZ3-GmRR18a-GmMYC2a-GmCKXs module regulated seed-related traits by the crosstalk between cytokinin and jasmonate (JA) signaling in soybean.
Through construction of gene co-expression network, GmJAZ3 was identified as a regulator for seed development and acted as a transcriptional repressor. Phenotype analysis of stable GmJAZ3-overexpression (OX) transgenic soybean plants indicated that GmJAZ3 promotes soybean plant growth, enhances seed size (Figure 1A) and weight, and alters lipid and protein levels.
Further study showed that GmJAZ3 largely inhibited the gene expression of three cytokinin oxidase gene GmCKXs. GmJAZ3 interacts with both GmRR18a and GmMYC2a to inhibit their activation on GmCKX for soybean seed size and weight control (Figure 1B). GmRR18a also activates GmMYC2a gene expression directly. The JAZ3 was selected during soybean domestication and its orthologues from other plants/crops may also control seed size and weight.
This finding defines a novel molecular module for seed weight/size control and provides promising targets during soybean molecular breeding for better seed traits.
This work entitled “GmJAZ3 interacts with GmRR18a and GmMYC2a to regulate seed traits in soybean” was published online in Journal of Integrative Plant Biology on April 17, 2023 (DOI: https://doi.org/10.1111/jipb.13494). This research was supported by the National Key R & D Project and other projects.
Figure. Phenotype analysis of GmJAZ3-overexpression plants and its working model (Image by IGDB). (A) Seed phenotypes of JACK, Null and GmJAZ3-overexpression plants after harvest. JACK is the original control cultivar. Null is segregated from heterozygous transgenic plants and without transgene insertion. Scale bar = 1 cm. (B) A working model depicting the regulation of soybean seed size and weight by GmJAZ3.
Dr. ZHANG Jinsong
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences