Improved Tolerance to Various Abiotic Stresses in Transgenic Sweet Potato (Ipomoea batatas) Expressing Spinach Betaine Aldehyde Dehydrogenase

Abstract

Abiotic stresses are critical delimiters for the increased productivity and cultivation expansion of sweet potato (Ipomoea batatas), a root crop with worldwide importance. The increased production of glycine betaine (GB) improves plant tolerance to various abiotic stresses without strong phenotypic changes, providing a feasible approach to improve stable yield production under unfavorable conditions. The gene encoding betaine aldehyde dehydrogenase (BADH) is involved in the biosynthesis of GB in plants, and the accumulation of GB by the heterologous overexpression of BADH improves abiotic stress tolerance in plants. This study is to improve sweet potato, a GB accumulator, resistant to multiple abiotic stresses by promoted GB biosynthesis. A chloroplastic BADH gene from Spinacia oleracea (SoBADH) was introduced into the sweet potato cultivar Sushu-2 via Agrobacterium-mediated transformation. The overexpression of SoBADH in the transgenic sweet potato improved tolerance to various abiotic stresses, including salt, oxidative stress, and low temperature. The increased BADH activity and GB accumulation in the transgenic plant lines under normal and multiple environmental stresses resulted in increased protection against cell damage through the maintenance of cell membrane integrity, stronger photosynthetic activity, reduced reactive oxygen species (ROS) production, and induction or activation of ROS scavenging by the increased activity of free radical-scavenging enzymes. The increased proline accumulation and systemic upregulation of many ROS-scavenging genes in stress-treated transgenic plants also indicated that GB accumulation might stimulate the ROS-scavenging system and proline biosynthesis via an integrative mechanism. This study demonstrates that the enhancement of GB biosynthesis in sweet potato is an effective and feasible approach to improve its tolerance to multiple abiotic stresses without causing phenotypic defects. This strategy for trait improvement in sweet potato not only stabilizes yield production in normal soils in unpredictable climates but also provides a novel germplasm for sweet potato production on marginal lands.

Cloning and characterization of a novel betaine aldehyde dehydrogenase gene from Suaeda corniculata

“…Missihoun et al (2011) showed that young and adult plants lacking ALDH10A8 transcripts were drought and salt sensitive. Similar results were found in sweet potato, in which those expressing spinach BADH had improved stress tolerance (Fan et al, 2012). In our study, we analyzed transgenic Arabidopsis plants expressing ScBADH under NaCl, PEG, and ABA treatments.…”

“…One common metabolic adaptation to salinity stress is the accumulation of osmoprotectants. One of these osmoprotectants, glycine betaine, is a bipolar quaternary ammonium compound, which accumulates in many plant species when subjected to various abiotic stresses (Rhodes and Hanson, 1993;Fan et al, 2012). Glycine betaine protects the plant from salt stress by maintaining the osmotic balance under various abiotic stresses (Wani et al, 2013) and by stabilizing the quaternary structure of complex proteins (Bernard et al, 1988).…”

“…Glycine betaine protects the plant from salt stress by maintaining the osmotic balance under various abiotic stresses (Wani et al, 2013) and by stabilizing the quaternary structure of complex proteins (Bernard et al, 1988). In photosynthetic systems, glycine betaine stabilizes the oxygen-evolving photosystem II complex and Rubisco at elevated salt concentrations (Zhou et al, 2008;Fan et al, 2012).…”

Genetic transformation and expression of transgenic lines of Populus x euramericana with insect-resistance and salt-tolerance genes

“…Betaine aldehyde dehydrogenase is a key enzyme in the synthesis of betaine, which is distributed in the chloroplast stroma, and its activity is induced by salt and drought. The BADH gene is the best drought resistant and salt tolerant gene for plants, and is widely used in plant breeding (Liu et al, 2011;Fan et al, 2012). Many studies have shown the BADH gene can be introduced into plants to improve salt tolerance.…”

Toxicity of OTC to Ipomoea aquatica Forsk. and to microorganisms in a long-term sewage-irrigated farmland soil

“…CAT activity increased continuously in both the leaves and roots with increasing OTC level but at 25 mg OTC kg −1 soil, the foliar CAT activity declined markedly to levels even lower than that in the controls. Spinach has been reported to be highly tolerant to many abiotic stresses (Shimazaki et al 1992;Fan et al 2012). Tolerant plant species protect themselves by using strong defence mechanisms, mostly as intensified antioxidant enzyme activity, and specialization of plant tolerance may be related to the influence of tissue and subcellular localization of enzymes and upstream sequences in the genomic sequence (Wilhelm 2006;Sánchez-Rodríguez et al 2011;Mittal et al 2012).…”