An improved method for transformation of lettuce by Agrobacterium tumefaciens with a gene that confers freezing resistance

Abstract

An efficient method for constructing transgenic lettuce cultivars by Agrobacterium tumefaciens was described by Torres et al., 1993. In the present work, an improvement of the above procedure is described and applied to transform the cultivar Grand Rapids with a mutated P5CS gene. The major modifications were concerned with turning more practical the transformation and regeneration protocols. Also we tried to improve transformation steps by increasing injured area in explants and prolonging co-cultivation with Agrobacteria (in larger concentration). A more significant selective pressure was used against non-transformed plants and bacteria. In these work we were concerned to obtain T 1 and T 2 seeds. The P5CS gene codes for a ∆ 1 -pyrroline-5-carboxylate synthetase, a bifunctional enzyme that catalyzes two steps of proline biosynthesis in plants (Zhang et al., 1995;Peng et al., 1996), while the mutated gene is insensitive to feedback inhibition by proline. The potential benefit of this gene is to confer water stress resistance (drought, salt, cold) due to increased intracellular levels of proline that works like an osmoprotectant. In this work could obtain and characterize transgenic lettuce lineages which are resistant to freezing temperature.

Over Expression of p5cs Gene to Increase Cold Stress Tolerance in Iranian Species of Petunia

“…This result is in agreement with those reported by Pileggi et al (2001) who found that p5cs caused cold resistance in lettuce. However, in transformed plant, significant accumulation of proline could be observed and there was almost 2 times increase in the proline content.…”

“…1 Department of Plant Breeding and Biotechnology, Sari Agricultural Sciences and Natural Resources University (SANRU), Sari, Iran. 2 Department of Plant Breeding and Biotechnology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. high acidity (Pileggi et al 2001, Rai and Suprassana 2013, Lv et al 2011, Nuccino et al 1999, Serrano 1996. It is well documented to be involved in response to osmotic stresses in a wide range of organisms.…”

Influence of exogenous L-proline on embryogenic cultures of larch (Larix leptoeuropaeaDengler), sitka spruce (Picea sitchensis(Bong.) Carr.) and oak (Quercus roburL.) subjected to cold and salt stress

“…This raises the possibility that forest species may also be protected from environmental stresses by manipulation of the accumulation of endogenous proline. Recent studies show that introduction of a gene for the rate-limiting enzyme in proline biosynthesis has produced improved environmental stress resistance in herbaceous dicots [16] and monocots [19]. The introduction of this gene into embryogenic cultures of forest species may therefore be a potent mechanism for introduction of stress tolerance into forest species, and their subsequent mass propagation [21].…”

Hybridization rates between lettuce (Lactuca sativa) and its wild relative (L. serriola) under field conditions

“…In addition, even if no transgenic variety has been commercialized yet, L. sativa has already been engineered for many traits such as herbicide resistance (McCabe et al, 1999;Nagata et al, 2000), pathogen resistance (Okubara et al, 1997) and other agronomic traits (Curtis et al, 1999;Goto et al, 2000;Pileggi et al, 2001). Although we did not investigate crop-wild lettuce hybridization using transgenic varieties, our results have clear implications for the risks assessment of their cultivation.…”