Evaluation of factors influencing Agrobacterium-mediated spinach transformation and transformant selection by EGFP fluorescence under low-selective pressure

• Published in: In vitro cellular & developmental biology. Plant Vol. 49; no. 5; pp. 498 - 509
• Main Authors: Nguyen, Quyen Van, Boo, Kyung Hwan, Sun, Hyeon Jin, Cao, Dang Viet, Lee, Doseung, Ko, Seung Hee, Kang, Seungtae, Yoon, Seonyoung, Kim, Seong Cheol, Park, Se Pill, Riu, Key-Zung, Lee, Dong-Sun
• Format: Journal Article
• Language: English
• Published: Boston Springer-Verlag 01.11.2013; Springer; Springer US; Springer Nature B.V
• Subjects: acetosyringone; Agrobacterium radiobacter; beta-glucuronidase; Biomedical and Life Sciences; Callus; Cell Biology; Cultivars; Cultivation; Developmental Biology; DNA; EMBRYOGENESIS/SOMATIC EMBRYOGENESIS; Embryos; Flowers & plants; Fluorescence; Genetic engineering; genetic techniques and protocols; genome; green fluorescent protein; Life Sciences; phosphinothricin acetyltransferase; Plant Breeding/Biotechnology; Plant cells; Plant Genetics and Genomics; Plant roots; Plant Sciences; Plants; Polymerase chain reaction; Rice; screening; shoots; Spinach; Spinacia oleracea; Studies; Transgenic plants; Vegetables; EGFP visualization; Spinach; Transformation factors; Somatic embryogenesis
• ISSN: 1054-5476; 1475-2689
• DOI: 10.1007/s11627-013-9534-8

We developed an efficient Agrobacterium-mediated transformation protocol for spinach (Spinacia oleracea L.) that uses root-derived callus. Evaluation of this protocol was based on the systematic evaluation of factors that influence transformation efficiency. Four of the five factors that were tested significantly affected the transformation efficiency, including spinach cultivar, Agrobacterium tumefaciens strain and density, and the duration of co-cultivation. Transgenic spinach plants were generated based on optimized conditions, consisting of callus explants of the cultivar Gyeowoonae, A. tumefaciens strain EHA105 with OD₆₀₀ of 0.2, a co-cultivation period of 4 d, and 100 μM acetosyringone supplemented in the inoculation and co-cultivation media. After co-cultivation with A. tumefaciens, explants were cultured in low-selective and then non-selective conditions to enhance the growth of putative transgenic explants. Visualization of the fluorescent marker, enhanced green fluorescent protein (EGFP), was used to select transgenic explants at several stages, including callus, somatic cotyledonary embryo, and plantlet. The best results for fluorescence visualization screening were obtained at the somatic cotyledonary embryo stage. On average, 24.96 ± 6.05% of the initial calli regenerated shoots that exhibited EGFP fluorescence. The putative transgenic plants were subjected to β-glucuronidase (GUS)-staining assay, phosphinothricin acetyltransferase (PAT) strip test, and molecular analyses to assess the transgene incorporation into plant genome and its expression. All EGFP-positive plants tested were confirmed to be transgenic by GUS-staining assay, PAT strip test, and molecular analyses. The transformation system described in this study could be a practical and powerful technique for functional genetic analysis and genetic modification of spinach.