Stress-inducible overexpression of trehalose biosynthetic genes in monocot plants improves drought tolerance and other agronomic traits
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abstract
We are genetically engineering cereal plants for drought tolerance via trehalose overproduction, and enhancing productivity.
Drought is the most devastating environmental constraint to the sustainability of agricultural production systems, and there is an urgent need to improve crop productivity under water-deficit conditions. One way to increase productivity in stressful environments is to breed crops that are more tolerant to stress. However, success in breeding for tolerance has been limited, because it is a very complex trait that is influenced by coordinated and differential expression of a network of genes. Fortunately, it is now possible to use transgenic technologies in conjunction with plant breeding tools to accelerate the selection and improvement of drought-related traits in agriculturally important crops to minimize yield losses and feed the growing world population.
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We obtained several putative transgenic monocot (rice, maize, and wheat) plants that were transformed with the binary plasmids containing trehalose biosynthetic genes. Compared to nontransgenic plants, several independent transgenic lines showed significantly higher levels of trehalose accumulation and other soluble sugars (glucose, sucrose) under drought-stress conditions. Similarly, drought-induced photo-oxidative damage to PS II was relatively smaller in the transgenic lines than in the nontransformed control plants. Importantly, trehalose-overproducing transgenic lines showed a more favorable cation mineral content in the leaves, and a substantially higher grain weight, than nontransgenic plants under greenhouse growth conditions. Our transgenic research work has a potential to create higher-yielding plants through cross-breeding with elite germplasm to introduce desirable traits into widely used varieties.
impact assessment
The recent discovery of a plethora of genes that encode trehalose metabolism enzymes in higher plants, with its potential role in modulating photosynthesis, carbon metabolism, and stress protection, has led to a series of scientific surprises and offers new challenges for researchers in this field. However, little is known about trehalose metabolism in the context of its interactions with carbon metabolism and development. Therefore, analysis of the tissue-specific expression of trehalose biosynthesis and degradation may shed light on the role of trehalose in abiotic stress tolerance, plant metabolism, growth and development, plant-pathogen interactions, and seed development. In view of the latest findings, trehalose research in plants should be seen as an opportunity to use multidisciplinary approaches for the dissection of metabolic networks, including the interface between sugar sensing-signaling and carbohydrate metabolism.
