Constitutive or seed‐specific overexpression of A rabidopsis G ‐protein γ subunit 3 ( AGG 3 ) results in increased seed and oil production and improved stress tolerance in C amelina sativa

Heterotrimeric G ‐proteins consisting of G α, G β and G γ subunits play an integral role in mediating multiple signalling pathways in plants. A novel, recently identified plant‐specific G γ protein, AGG 3, has been proposed to be an important regulator of organ size and mediator of stress responses in A rabidopsis, whereas its potential homologs in rice are major quantitative trait loci for seed size and panicle branching. To evaluate the role of AGG 3 towards seed and oil yield improvement, the gene was overexpressed in C amelina sativa , an oilseed crop of the B rassicaceae family. Analysis of multiple homozygous T 4 transgenic C amelina lines showed that constitutive overexpression of AGG 3 resulted in faster vegetative as well as reproductive growth accompanied by an increase in photosynthetic efficiency. Moreover, when expressed constitutively or specifically in seed tissue, AGG 3 was found to increase seed size, seed mass and seed number per plant by 15%–40%, effectively resulting in significantly higher oil yield per plant. AGG 3 overexpressing C amelina plants also exhibited improved stress tolerance. These observations draw a strong link between the roles of AGG 3 in regulating two critical yield parameters, seed traits and plant stress responses, and reveal an effective biotechnological tool to dramatically increase yield in agricultural crops.