Expression analysis of crucial fructan genes (1-sst, 6G-fft and 1-fft) in Aloe vera plants subjected to water stress and a possible regulation of these genes by ABA.

Abstract

The monocot CAM plant Aloe barbadensis Miller, also known as Aloe vera, is well adapted to live in arid environments. Xerophytic plants have developed diverse response mechanisms to cope with the abiotic stresses produced by these environments. The synthesis and accumulation of different polysaccharides e.g.,fructans, in plants has been shown to protect the integrity and function of cell membranes and proteins during dehydration caused by water stress [1]. Previous results from our group [2] have shown that Aloe vera plants subjected to moderate (50% field capacity (FC) irrigation) and severe water deficit (25% FC irrigation) have higher concentrations of fructans (Figure 1A). Glycosidic linkage analysis indicated that fructans from water stressed Aloe plants increased in a highly branched sub-type of fructans, neo-fructans. We also found a significant increase in the degree of polymerization in fructans from 25% FC plants. In our current study we have analyzed the expression of three crucial genes involved in fructan biosynthesis in Aloe vera (Figure 1B); 1-sst, sucrose: sucrose 1-fructosyltransferase which synthesizes the trisaccharide 1-kestose; 6G-fft, fructan: fructan 6G-fructosyltransferase that produces the trisaccharide neo-kestose and 1-fft, fructan: fructan 1-fructosyltransferase which elongates the fructan polymer. By RT-qPCR we determined the effect of water stress and the plant stress hormone ABA have on the expression of these genes in Aloe vera