Document Type

Poster

Date of Original Version

3-27-2026

Abstract

Reliable Agrobacterium mediated transformation of Sorghum remains constrained by low transformation frequencies and the requirement for high quality immature embryos (IEs). A useful conceptual framework describes transformation efficiency T=V(Cd×Ci×Cr), as the product of DNA delivery (Cd), stable integration (Ci), regeneration competence (Cr), and experiment specific variables (V). Using this framework, in a multi-year study we systematically evaluated parameters predicted to influence DNA delivery and regeneration. Standard IE workflows established baseline developmental dynamics of somatic embryogenesis and regeneration. To increase DNA delivery, we tested Agrobacterium strains and ternary vir helper vectors, which enhanced bacterial attachment and transient reporter expression. To elevate the proportion of transformed cells progressing through embryogenesis, we compared two classes of developmental regulators: BBM/WUS2 delivered altruistically, and GRF/GIF delivered on the integrating T DNA. BBM/WUS2 accelerated somatic embryogenesis on the scutellar epidermis, producing an increased proliferation of transformed cells entering embryogenic pathways. GRF/GIF further increased transformation frequencies while markedly shortening the callus phase, consistent with accelerated organization of shoot apical domes, enabling transformed tissues to reach regeneration competency earlier than in standard workflows. Media composition modulated regeneration outcomes, with different plant growth regulator regimes generating early callus formation, but only the Wu based media consistently supporting full regeneration under GRF/GIF induction. Across all experiments, the standard protocol reliably produced low copy, heritable insertions but remained efficiency limited, whereas combined optimization of developmental regulator strategy, ternary T DNA delivery, and stage matched media substantially improved overall transformation success and increased the throughput of regenerated events.

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