Plasma membrane (PM) H+-ATPase, which catalyzes ATP hydrolysis coupled with pumping out protons from cells and which is ubiquitously existent in all cell types of plants examined so far, has been characterized to be encoded by a multigene family involved in a number of plant physiological and developmental processes. The aim of this study is to identify and characterize the genes encoding PM H+-ATPase in Solanum lycopersicum (tomato). Through genomic sequence database hunting and bioinformatics analysis, eight putative PM H+-ATPase genes (named as LHA1-8) were identified, and their expression patterns were subsequently analysed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Bioinformatics analysis revealed a high conservation among these paralogous genes in both coding sequences and Exon/Intron structures. Expression analysis showed that LHA1, LHA2, LHA3, and LHA4 were expressed in all tissues examined; whereas LHA5, LHA6, and LHA7 were predominantly expressed in flowers. LHA8, the newly identified gene in this study, with barely detectable transcripts in normal growth conditions or in nutrient (N, P, K, and Mg) -deficient conditions, was strongly induced in arbuscular mycorrhizal (AM) fungal-colonized roots. A 2 669 bp LHA8 promoter fragment could direct the β-glucuronidase (GUS) reporter expression specifically in transgenic tobacco roots colonized by AM fungi. The results provide new insights into the evolutionary conservation and functional divergence of the tomato PM H+-ATPase gene family during plant growth and development.[Ch, 5 fig. 2 tab. 22 ref.]