Abstract:

Aluminum (Al) toxicity is a major constraint factor for crop production in acidic soil worldwide. The Al toxicity can cause inhibition of cell elongation and cell division, leading to root stunting accompanied by reduced water and nutrient uptake. With respect of genetic analysis of Al tolerance, the work has been done in cereals especially among members of the Triticeae (eg, wheat, rye). It was reported that seven wheat aluminum-induced genes (wali1, -2, -3, -4, -5, -6 and -7) were isolated from an Al-sensitive wheat cultivar (Triticum aestivum L. cv. Warigal), which are response to Aluminum stress. The wali1 encoded a plant metallothionein-like protein, homologous to the proteins from a number of other plant species, such as Arabidopsis thaliana, Glycine max, Pisum sativum, Mimulus guttatus, Zea mays and Hordeum vulgare. The wali2 coding protein has no significant homology with any sequence currently in the databases. The proteins encoded by wali3, wali5 and wali6 are the members of serine proteinase inhibitor- Bowman-Birk family, which have the conserved Bowman-Birk domains. The protein which wali4 encoded shows homology to the enzyme PAL. The protein encoded by wali7, a member of Gn-AT-II superfamily, has significant homology with stem-specific proteins from Zea mays and Oryza sativa. Subsequently, a β-1,3-glucanase gene and fimbrin-like mRNA were isolated from an Al-sensitive wheat (T. aestivum L. cv. Victory) cultivar. Using differential screening of a root tip cDNA library prepared from an Al-tolerant wheat cultivar (T. aestivum L. cv. Atlas-66) exposed to Al, it was reported that several wheat aluminum-regulated (War) genes were cloned. Sequence comparison revealed that the genes up-regulated by Al encode peroxidase (war4.2), cysteine proteinase (war5.2), phenylalanine-ammonia lyase (war7.2), and oxalate oxidase (war13.2), respectively. The Al toxicity affects the biological functions of the plant in many different aspects. However, plant cells are well equipped with many ways help to detoxify. This article reviews the progress of the basic structure, biological function, expression regulation of the genes related to wheat aluminum stress and their novel research.