Overexpression of the Aldehyde Dehydrogenase Gene ZmALDH Confers Aluminum Tolerance in Arabidopsis thaliana

Aluminum (Al) toxicity is the main factor limiting plant growth and the yield of cereal crops in acidic soils. Al-induced oxidative stress could lead to the excessive accumulation of reactive oxygen species (ROS) and aldehydes in plants. Aldehyde dehydrogenase (ALDH) genes, which play an important role in detoxification of aldehydes when exposed to abiotic stress, have been identified in most species. However, little is known about the function of this gene family in the response to Al stress. Here, we identified an ALDH gene in maize, ZmALDH, involved in protection against Al-induced oxidative stress. Al stress up-regulated ZmALDH expression in both the roots and leaves. The expression of ZmALDH only responded to Al toxicity but not to other stresses including low pH and other metals. The heterologous overexpression of ZmALDH in Arabidopsis increased Al tolerance by promoting the ascorbate-glutathione cycle, increasing the transcript levels of antioxidant enzyme genes as well as the activities of their products, reducing MDA, and increasing free proline synthesis. The overexpression of ZmALDH also reduced Al accumulation in roots. Taken together, these findings suggest that ZmALDH participates in Al-induced oxidative stress and Al accumulation in roots, conferring Al tolerance in transgenic Arabidopsis.

Aluminum resistance of malting barley

Background. Barley is the second cereal crop in Russia in terms of its importance and production volume. It is used for food, feed, and industrial purposes. The production of malting barley in Russia exceeds 1.5 million tons; each year the area under this crop increases by 10–15%, reaching 600,000– 800,000 hectares. Barleys suitable for brewing must have certain physicochemical and technological properties. The main requirements for raw materials are presented in GOST 5060-86 (state standard for malting barley). An important condition for obtaining sustainable harvests is the development and utilization of cultivars resistant to a set of edaphic stressors. The purpose of this work was searching for resistant cultivars for use in targeted breeding.Materials and methods. The material for the study included 161 spring barley cultivars for brewing from the collection of plant genetic resources held by VIR. The laboratory assessment of aluminum tolerance in barley accessions was carried out at the initial phases of plant growth and development, using the method of calculating root and shoot length indices. The tested malting barley was classified into five resistance groups.Results and conclusions. Cultivars resistant to Al3+ ions were identified among different ecogeographic groups of malting barleys. The trait had a wide range of variability in terms of both the root length index (0.17–0.95) and shoot length index (0.47–0.99). Accessions with high resistance to ionic (Al3+) stress can be used in barley breeding targeted at the development of high-yielding malting cultivars most adapted to harmful environmental factors.

Identification of an ATP-Binding Cassette Transporter Implicated in Aluminum Tolerance in Wild Soybean (Glycine soja)

The toxicity of aluminum (Al) in acidic soil limits global crop yield. The ATP-binding cassette (ABC) transporter-like gene superfamily has functions and structures related to transportation, so it responds to aluminum stress in plants. In this study, one half-size ABC transporter gene was isolated from wild soybeans (Glycine soja) and designated GsABCI1. By real-time qPCR, GsABCI1 was identified as not specifically expressed in tissues. Phenotype identification of the overexpressed transgenic lines showed increased tolerance to aluminum. Furthermore, GsABCI1 transgenic plants exhibited some resistance to aluminum treatment by ion translocation or changing root components. This work on the GsABCI1 identified the molecular function, which provided useful information for understanding the gene function of the ABC family and the development of new aluminum-tolerant soybean germplasm.