Etr1-1 Gene Expression Alters Regeneration Patterns in Transgenic Lettuce Stimulating Root Formation |
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Authors: | Jong Hee Kim JR Botella |
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Institution: | (1) Department of Biological Sciences, KyungNam University, Masan, 604-701, South Korea;(2) Department of Botany, University of Queensland, Brisbane, Qld, 4072, Australia |
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Abstract: | We have evaluated the transformation efficiency of two lettuce (Lactuca sativa L.) cultivars, LE126 and Seagreen, using Agrobacterium tumefaciens-mediated gene transfer. Six-day-old cotyledons were co-cultivated with Agrobacterium cultures carrying binary vectors with two different genetic constructs. The first construct contained the β-glucuronidase
gene (GUS) under the control of the cauliflower mosaic virus 35S promoter (CaMV 35S), while the second construct contained
the ethylene mutant receptor etr1-1, which confers ethylene insensitivity, under the control of a leaf senescence-specific promoter (sag12). Tissues co-cultivated with the GUS construct showed strong regeneration potential with over 90% of explants developing
callus masses and 85% of the calli developing shoots. Histochemical GUS assays showed that 85.7% of the plants recovered were
transgenic. Very different results were observed when cotyledon explants were co-cultivated with Agrobacteria carrying the etr1-1 gene. There was a dramatic effect on the regeneration properties of the cultured explants with root formation taking place
directly from the cotyledon tissue in 34% of the explants and no callus or shoots observed initially. Eventually callus formed
in 10% of cotyledons and some organogenic shoots were obtained (2.86%). These results indicate that the ethylene insensitivity
conferred by the etr1-1 gene alters the normal pattern of regeneration in lettuce cotyledons, inhibiting the formation of shoots and stimulating
root formation during regeneration. |
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Keywords: | Agrobacterium tumefaciens Etr1-1 intron GUS Lactuca sativa L LBA4404 transformation |
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