Transplastomic plants for innovations in agriculture. A review

Food production has to be significantly increased in order to feed the fast growing global population estimated to be 9.1 billion by 2050. The Green Revolution and the development of advanced plant breeding tools have led to a significant increase in agricultural production since the 1960s. However, hundreds of millions of humans are still undernourished, while the area of total arable land is close to its maximum utilization and may even decrease due to climate change, urbanization, and pollution. All these issues necessitate a second Green Revolution, in which biotechnological engineering of economically and nutritionally important traits should be critically and carefully considered. Since the early 1990s, possible applications of plastid transformation in higher plants have been constantly developed. These represent viable alternatives to existing nuclear transgenic technologies, especially due to the better transgene containment of transplastomic plants. Here, we present an overview of plastid engineering techniques and their applications to improve crop quality and productivity under adverse growth conditions. These applications include (1) transplastomic plants producing insecticidal, antibacterial, and antifungal compounds. These plants are therefore resistant to pests and require less pesticides. (2) Transplastomic plants resistant to cold, drought, salt, chemical, and oxidative stress. Some pollution tolerant plants could even be used for phytoremediation. (3) Transplastomic plants having higher productivity as a result of improved photosynthesis. (4) Transplastomic plants with enhanced mineral, micronutrient, and macronutrient contents. We also evaluate field trials, biosafety issues, and public concerns on transplastomic plants. Nevertheless, the transplastomic technology is still unavailable for most staple crops, including cereals. Transplastomic plants have not been commercialized so far, but if this crop limitation were overcome, they could contribute to sustainable development in agriculture.