Abstract

MhGlu, a β-1, 3-glucanase cDNA, was cloned from Malus hupehensis (Pamp.) Rehd by in silico cloning and validated with RT-PCR. MhGlu has an intron and possess 84, 83, and 77% nucleotide identity and 84, 74, and 76% amino acid identity with Prunus persica, Prunus avium, and Vitis riparia, respectively. MhGlu genomic DNA sequence and promoter sequence including the salicylic acid (SA) motif, methyl jasmonate (MeJA) responsive, and ethylene (ET) responsive elements were isolated. MhGlu expression was detected in M. hupehensis seedlings treated with SA, MeJA and 1-aminocyclopropane-1-carboxylic acid (ACC). Real-time quantitative RT-PCR (qRT-PCR) revealed constitutive expression of MhGlu in leaf but not in the stem and root where it was silent and induced by SA, MeJA, and ET. This result suggests that MhGlu might be involved in the SA- and the JA/ET-signaling pathways in M. hupehensis. The expression of the gene monitored in a 96 h course after inoculation with apple ring spot pathogen (Botryosphaeria berengeriana de Not. f. sp. Parabola Nise Koganezawa et Sakuma). Inoculation with B. berengeriana, up-regulated MhGlu 24 h post inoculation (PI), the expression reached to maximum at 48 h PI, and then decline. Moreover, apple aphid (Aphis citricota van der Goot) could enhance MhGlu expression in the leaf and stem compared to healthy control plants. It can be concluded from the results that MhGlu is involved in resistance to biotic stress in M. hupehensis.

Key words: β-1, 3-glucanase, expression analysis, Malus hupehensis, promoter, salicylic acid (SA), jasmonic acid (JA), pathways.