REVIEW Transcription factors involved in acid stress responses in plants Chuan-Ming Yeh 1 & Masaru Ohme-Takagi 1,2 Received: 12 January 2016 / # Archana Sharma Foundation of Calcutta 2016 Abstract With the fast growth of world population and climate change, agricultural production is being a main global issue and challenge. Leading to deficiencies of several essential elements and toxicity of heavy metals in plants, acid soil is one of the most important limitations to crop productivity worldwide. Although lime is widely used to ameliorate acid soil, it is not economic and ideal. Identification of the mechanisms and genes conferring tol- erance to acid soil stress could be an alternative way to improve the productivity in acid soil through breeding tolerant crops. Aluminum (Al) toxicity and phosphorous (P) deficiency are con- sidered as two severe constraints to plant growth in acid soil. Several genes related to tolerance to Al toxicity and P deficiency have been identified and analysed in various crop plants. This review describes the current understanding of transcription fac- tors involved in the transcriptional regulation of tolerance to Al toxicity and P deficiency in Arabidopsis and rice. Keywords Acid soil . Aluminum toxicity . Phosphorous deficiency . Transcription factors Introduction The global population will probably increase by more than 3 billion to over 9 billion by 2050 leading to a much greater demand for food crops and feed grains [14]. To support these demands, it is necessary to improve crop yields or extend agricultural land area. Unfortunately, much of the extra land suffers from chemical, physical or biological constraints, im- peding the utilization [40, 62]. In addition, as much as 50 % of potentially arable lands in the world compose of acid soils [41], which dramatically restrict crop productivity, and the acidification of agricultural lands is accelerated by excessive use of chemical fertilizers and acid rain [49, 54]. Therefore, acid soil is one of the most important limitations to global crop production. Lime is widely used to ameliorate acid soils, but it is not economic in many developing countries and surface application is not often effective when acidity extends to depth [28, 36, 40]. A combination strategy of conventional liming and breeding of acid soil-tolerant crops could be considered to meet the future challenges. Acid soils are defined as soils with pH lower than 5.5 in their surface [28, 40]. The low pH of acid soils results in deficiency of several essential elements, including nitrogen, phosphorus (P), potassium and molybdenum. In addition, acidification induces toxicity of proton and heavy metals, namely aluminum (Al), iron and manganese [36, 74]. P defi- ciency and Al toxicity are considered as two of the most im- portant limiting factors in acid soils. Emerging evidences show that toxicity of other heavy metals and multiple nutrition deficiencies interplay the complex Bacid-soil syndrome’ [34, 40]. However, over the past decade, much attention has been paid on addressing the mechanisms adapted by plants against Al toxicity and P deficiency. The strategies of plants to cope with Al stress are external tolerance that facilitates Al exclu- sion from the root apex and internal tolerance that chelates Al in the cytosol and subsequently sequester in the vacuoles [51]. Several genes that are involved in these processes have been identified. Those include Al-activated malate transporter (ALMT), multidrug and toxic compound extrusion (MATE) * Masaru Ohme-Takagi mtakagi@mail.saitama-u.ac.jp 1 Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan 2 Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tukuba, Ibaraki 305-8566, Japan Nucleus DOI 10.1007/s13237-016-0159-2