Developing a flexible, high-efficiency Agrobacterium-mediated sorghum transformation system with broad application.

Che P, Anand A, Wu E, Sander JD, Simon MK, Zhu W, Sigmund AL, Zastrow-Hayes G, Miller M, Liu D, Lawit SJ, Zhao ZY, Albertsen MC, Jones TJ

Published: 13 January 2018 in Plant biotechnology journal
Keywords: Agrobacterium, Africa sorghum varieties, CRISPR/Cas9, genome modification, sorghum transformation, ternary vector
Pubmed ID: 29327444
DOI: 10.1111/pbi.12879

Sorghum is the fifth most widely planted cereal crop in the world and is commonly cultivated in arid and semi-arid regions such as Africa. Despite its importance as a food source, sorghum genetic improvement through transgenic approaches has been limited because of an inefficient transformation system. Here, we report a ternary vector (also known as cohabitating vector) system using a recently described pVIR accessory plasmid that facilitates efficient Agrobacterium-mediated transformation of sorghum. We report regeneration frequencies ranging from 6% to 29% in Tx430 using different selectable markers and single copy, backbone free 'quality events' ranging from 45% to 66% of the total events produced. Furthermore, we successfully applied this ternary system to develop transformation protocols for popular but recalcitrant African varieties including Macia, Malisor 84-7 and Tegemeo. In addition, we report the use of this technology to develop the first stable CRISPR/Cas9-mediated gene knockouts in Tx430.