Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

Table 2

Transgenic plants or cells with higher aluminum- (Al-) tolerance overexpressing genes for the biosynthesis and the secretion of organic acid (OA) anions.

Genes	Origins	Transgenic plants or cells	Increased secretions of OA anions	Al tolerance	References
Citrate synthase (CS)	Pseudomonas aeruginosa	Papaya (Carica papaya)	NA	+	[108]
		Tobacco (Nicotiana tabacum)	Citrate	+	[108]
		Tobacco	No	No	[40]
		Alfalfa (Medicago sativa)	No	No	[40]
		Alfalfa	NA	+	[133]
	Arabidopsis thaliana	Rape (Brassica napus)	Citrate	+	[58]
		Carrot (Daucus carota) cell	Citrate	+	[109]
	Citrus junos	Nicotiana benthamiana	Citrate	+	[24]
	Carrot	A. thaliana	Citrate	+	[134]
	Rice (Oryza sativa)	Tobacco	Citrate	+	[111]
Malate dehydrogenase (MDH)	C. junos	Tobacco	NA	+	[135]
	A. thaliana,   Escherichia coli	Tobacco	Malate	+	[110]
Nodule-enhanced form of MDH (neMDH)	Alfalfa	Alfalfa	Citrate, oxalate, malate, succinate, acetate	+	[112]
Phosphoenolpyruvate carboxylase (PEPC)	Alfalfa	Alfalfa	No	No	[112]
Pyruvate phosphate dikinase (PPDK)	Mesembryanthemum crystallinum	Tobacco	Citrate, malate	+	[113]
TaALMT1	Wheat (Triticum aestivum)	Tobacco cells	Malate	+	[73]
		Rice	Malate	No	[73]
		Barley	Malate	+	[136, 137]
		Wheat	Malate	+	[138]
		A. thaliana	Malate	+	[107]
AtALMT1	A. thaliana	A. thaliana	Malate		[107]
BnALMT1 and BnALMT1	Rape	Tobacco cells	Malate	+	[76]
HvALMT1	Barley	Barley	Malate	+	[87]
HvAACT1	Barley	Tobacco	Citrate	+	[88]
SbMATE	Sorghum (Sorghum bicolor)	A. thaliana	Citrate	+	[53]
FRD3	A. thaliana	A. thaliana	Citrate	+	[94]
ZmMATE1	Maize	A. thaliana	Citrate	+	[96]
VuMATE	Vigna umbellata	Tomato	Citrate	+	[98]
Plasma membrane 𝐻^+-ATPase	A. thaliana	A. thaliana	Citrate	NA	[117]
Type 1 𝐻^+-pyrophosphatase (AVP1)	A. thaliana	A. thaliana, tomato, and rice	Malate	+	[139]

NA: not applicable; No: no change in secretion of OA anions or Al tolerance.