Molecular characterization, expression and functional analysis of acyl-CoA-binding protein gene family in maize (Zea mays)

Abstract

Background Acyl-CoA-binding proteins (ACBPs) possess a conserved acyl-CoA-binding (ACB) domain that facilitates binding to acyl-CoA esters and trafficking in eukaryotic cells. Although the various functions of ACBP have been characterized in several plant species, their structure, molecular evolution, expression profile, and function have not been fully elucidated in Zea mays L. Results Genome-wide analysis identified nine ZmACBP genes in Z. mays, which could be divided into four distinct classes (class I, class II, class III, and class IV) via construction of a phylogenetic tree that included 48 ACBP genes from six different plant species. Transient expression of a ZmACBP-GFP fusion protein in tobacco (Nicotiana tabacum) epidermal cells revealed that ZmACBPs localized to multiple different locations. Analyses of expression profiles revealed that ZmACBPs exhibited temporal and spatial expression changes during abiotic and biotic stresses. Eight of the nine ZmACBP genes were also found to have significant association with agronomic traits in a panel of 500 maize inbred lines. The heterologous constitutive expression of ZmACBP1 and ZmACBP3 in Arabidopsis enhanced the resistance of these plants to salinity and drought stress, possibly through alterations in the level of lipid metabolic and stress-responsive genes. Conclusion The ACBP gene family was highly conserved across different plant species. ZmACBP genes had clear tissue and organ expression specificity and were responsive to both biotic and abiotic stresses, suggesting their roles in plant growth and stress resistance.

Plant Acyl-CoA-Binding Proteins—Their Lipid and Protein Interactors in Abiotic and Biotic Stresses

“…Following the discovery of BnACBP, similar 10-kDa ACBPs emerged in Arabidopsis thaliana [ 95 ], Gossypium hirsutum (cotton) [ 96 ], Ricinus communis (castor bean) [ 97 ], Digitalis lanata Ehrh. (Wolly Foxglove) [ 98 ], Oryza sativa (rice) [ 89 ], Vernicia fordii (tung tree) [ 99 ], Vitis vinifera (grape) [ 100 ], Helianthus annuus (sunflower) [ 101 ], Elaeis guineensis (oil palm) [ 102 ], Zea mays (maize) [ 103 ] and Glycine max (soybean) [ 104 ].…”

“…In plants such as Arabidopsis, rice, oilseed rape, oil palm, maize and soybean, ACBPs are classified into four main groups according to size and domains: Class I small ACBPs, Class II ACBPs containing ankyrin repeats, Class III large ACBPs and Class IV ACBPs containing kelch motifs ( Table 1 ) [ 89 , 102 , 103 , 104 , 105 ]. Table 1 shows that Class I ACBPs range from 10 to 17 kDa, whereas the others comprised of a transmembrane domain, ankyrin repeats and/or kelch motifs, have molecular weights of 34 to 85 kDa [ 89 , 103 ]. Arabidopsis ACBPs are localised to the ER and plasma membrane (AtACBP1 and AtACBP2) [ 106 , 107 ], apoplast (AtACBP3) [ 108 ] and cytosol (AtACBP4 to AtACBP6) [ 87 , 109 ].…”

“…On the other hand, rice ACBPs are subcellularly localised to the cytosol (OsACBP1 to OsACBP3) [ 91 ], ER (OsACBP4) [ 91 , 110 ], apoplast (OsACBP5) [ 111 ] and peroxisomes (OsACBP6) [ 91 ]. In maize, transient expression of green fluorescent protein (GFP)-tagged Class I ZmACBP1 in Nicotiana benthamiana leaf epidermal cells revealed that ZmACBP1 was confined to the cytosol, Class II ZmACBP3 localised to the ER, whereas Class III and IV ZmACBP6 and ZmACBP7, respectively, were targeted to both the cytosol and the plasma membrane [ 103 ]. Oil palm Class II EgACBP2 contains an N -terminal transmembrane domain responsible for protein targeting to the plasma membrane, and two C -terminal ankyrin repeats which could mediate protein-protein interactions and other cellular activities [ 102 ].…”

“…Other than AtACBPs, grape VvACBP was upregulated in leaves upon cold and heat shock stresses in comparison to the nontreated control [ 100 ]. In maize, the expression levels of ZmACBP2 , ZmACBP3 , ZmACBP5 and ZmACBP6 were induced by cold stress while ZmACBP1 , ZmACBP4 , ZmACBP7 , ZmACBP8 and ZmACBP9 mRNA levels declined after cold treatment [ 103 ]. These changes in expression levels depicted the potential roles of ZmACBPs in cold stress response which remain to be further elucidated.…”

“…A recent study by Zhu et al [ 103 ] showed that Class I ZmACBP1 and Class II ZmACBP3 gene expression was induced after NaCl or mannitol treatment. Transgenic Arabidopsis overexpressing ZmACBP1 and ZmACBP3 exhibited better growth and longer roots in comparison to the vector control [ 103 ].…”