Chloroplast-transgenic plants: Panacea-No! Gene Containment-Yes!

Daniell, Henry; Varma, Sam

doi:10.1038/nbt0798-602

Cited by 11 publications

(3 citation statements)

References 14 publications

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“…This alternative approach enables the accumulation of higher levels of heterologous proteins enclosed in the organelle, with reported values of up to 51% and even 70% of total soluble protein (TSP) in Nicotiana tabacum plants 35,36 . Other advantages over nuclear genome transformation include the absence of positional effects and silencing, as well as the reduced risk of transgene transfer to compatible wild relatives as a consequence of the maternal inheritance of plastids in many crops 37,38 . Transplastomic plants have been developed for multiple purposes, including but not limited to, molecular farming, metabolic engineering, and phytoremediation 39 .…”

Section: Introductionmentioning

confidence: 99%

Expression of pathogenesis-related proteins in transplastomic tobacco plants confers resistance to filamentous pathogens under field trials

Boccardo

Segretin

Hernández

et al. 2019

Sci Rep

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Plants are continuously challenged by pathogens, affecting most staple crops compromising food security. They have evolved different mechanisms to counterattack pathogen infection, including the accumulation of pathogenesis-related (PR) proteins. These proteins have been implicated in active defense, and their overexpression has led to enhanced resistance in nuclear transgenic plants, although in many cases constitutive expression resulted in lesion-mimic phenotypes. We decided to evaluate plastid transformation as an alternative to overcome limitations observed for nuclear transgenic technologies. The advantages include the possibilities to express polycistronic RNAs, to obtain higher protein expression levels, and the impeded gene flow due to the maternal inheritance of the plastome. We transformed Nicotiana tabacum plastids to co-express the tobacco PR proteins AP24 and β-1,3-glucanase. Transplastomic tobacco lines were characterized and subsequently challenged with Rhizoctonia solani , Peronospora hyoscyami f.sp. tabacina and Phytophthora nicotianae . Results showed that transplastomic plants expressing AP24 and β-1,3-glucanase are resistant to R . solani in greenhouse conditions and, furthermore, they are protected against P . hyoscyami f.sp. tabacina and P . nicotianae in field conditions under high inoculum pressure. Our results suggest that plastid co- expression of PR proteins AP24 and β-1,3-glucanase resulted in enhanced resistance against filamentous pathogens.

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Section: Introductionmentioning

confidence: 99%

Expression of pathogenesis-related proteins in transplastomic tobacco plants confers resistance to filamentous pathogens under field trials

Boccardo

Segretin

Hernández

et al. 2019

Sci Rep

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“…Advantages compared with the nuclear genome transformation include the absence of positional effects and the maternal inheritance of plastids in many of the cultivated species, reducing the risk of transgene transfer to compatible wild relatives (Daniell and Varma 1998).…”

Section: Introductionmentioning

confidence: 99%

Transformation of Solanum tuberosum plastids allows high expression levels of β-glucuronidase both in leaves and microtubers developed in vitro

Segretin

Lentz

Wirth

et al. 2011

Planta

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Plastid genome transformation offers an attractive methodology for transgene expression in plants, but for potato, only expression of gfp transgene (besides the selective gene aadA) has been published. We report here successful expression of β-glucuronidase in transplastomic Solanum tuberosum (var. Desiree) plants, with accumulation levels for the recombinant protein of up to 41% of total soluble protein in mature leaves. To our knowledge, this is the highest expression level reported for a heterologous protein in S. tuberosum. Accumulation of the recombinant protein in soil-grown minitubers was very low, as described in previous reports. Interestingly, microtubers developed in vitro showed higher accumulation of β-glucuronidase. As light exposure during their development could be the trigger for this high accumulation, we analyzed the effect of light on β-glucuronidase accumulation in transplastomic tubers. Exposure to light for 8 days increased β-glucuronidase accumulation in soil-grown tubers, acting as a light-inducible expression system for recombinant protein accumulation in tuber plastids. In this paper we show that plastid transformation in potato allows the highest recombinant protein accumulation in foliar tissue described so far for this food crop. We also demonstrate that in tubers high accumulation is possible and depends on light exposure. Because tubers have many advantages as protein storage organs, these results could lead to new recombinant protein production schemes based on potato.

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“…It was originally suggested that "chloroplast transformation provides containment of foreign genes because plastid transgenes are not transmitted by pollen" 1 . This remark stimulated considerable debate 3-5 that centered largely on the validity of the unintended interpretation 6 that chloroplasts are always maternally inherited in crops. The mode of chloroplast inheritance is uncharacterized in some cultivated species, although data are available for many of the crops that are commonly subjected to genetic modification 7 .…”

Section: Researchmentioning

confidence: 97%

Low probability of chloroplast movement from oilseed rape (Brassica napus) into wild Brassica rapa

Scott

Wilkinson

1999

Nat Biotechnol

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Pollen-mediated movement of transgenes from transplastomic oilseed rape (Brassica napus) into wild relatives will be avoided if chloroplasts are maternally transmitted. We assess the probability of chloroplast exchange between conventional oilseed rape and wild Brassica rapa to model the future behavior of transplastomic cultivars. Primers specific to cpDNA were used to demonstrate maternal inheritance of chloroplasts in 47 natural hybrids between cultivated B. napus and wild B. rapa. We conclude that there will be no or negligible pollen-mediated chloroplast dispersal from oilseed rape. Transgene introgression could still occur in mixed populations, however, if B. napus acted as the recurrent female parent. Rate of transfer would then depend on the abundance of mixed populations, their persistence as mixtures, and hybridization frequency within stands. A low incidence of sympatry (0.6-0.7%) between wild B. rapa and cultivated B. napus along the river Thames, UK, in 1997 and 1998, suggests mixed stands will form only rarely. Eighteen feral populations of B. napus also showed a strong tendency toward rapid decline in plant number, seed return, and ultimately, extinction within 3 years. Conversely, hybrid production is significant in mixed stands, and the absence of control practices means that oilseed rape will have slightly greater persistence. We infer that some introgression from transplastomic B. napus into B. rapa is inevitable in mixed populations even though such populations will occur infrequently and will tend to lose B. napus plants relatively quickly. Chloroplast exchange will be extremely rare and scattered.

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Chloroplast-transgenic plants: Panacea-No! Gene Containment-Yes!

Cited by 11 publications

References 14 publications

Expression of pathogenesis-related proteins in transplastomic tobacco plants confers resistance to filamentous pathogens under field trials

Expression of pathogenesis-related proteins in transplastomic tobacco plants confers resistance to filamentous pathogens under field trials

Transformation of Solanum tuberosum plastids allows high expression levels of β-glucuronidase both in leaves and microtubers developed in vitro

Low probability of chloroplast movement from oilseed rape (Brassica napus) into wild Brassica rapa

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