Cloning and functional characterization of MhPSY1 gene from Malus halliana in apple calli and Arabidopsis thaliana

Salinization is a universal problem in the world, which seriously affects the growth and development of plants, limit the quality and yield. Additionally, the study of stress-related genes and their regulatory molecular mechanisms is of great importance to cope with saline-alkali stress. In this study, based on transcriptome of Malus halliana , we screened out the gene Phytoene synthase 1 ( PSY1 , LOC103405286) significantly induced by saline-alkali stress in carotenoid metabolic pathways. Quantitative real-time PCR confirmed that the expression level of MhPSY1 was significantly down-regulated in the leaves of M. halliana under saline-alkali conditions. Subsequently, MhPSY1 gene was isolated and its functional characteristics were further studied in Arabidopsis thaliana and apple calli. Bioinformatics analysis found that MhPSY1 contains a complete open reading frame with a length of 1191 bp and encodes 396 amino acids with an isoelectric point of 9.06, which is an alkaline protein. Phylogenetic tree analysis showed that MhPSY1 had the highest homology and the closest genetic relationship with Pyrus × bretschneideri . Stress resistance test showed that overexpression of MhPSY1 reduced the tolerance of Arabidopsis thaliana and apple calli to saline-alkali stress and the main basis is as follows: the SOD, POD and CAT activities of overexpressed apple calli and transgenic Arabidopsis were significantly lower than those of wild type (WT), malondialdehyde (MDA) content was significantly higher than that of WT and proline content was lower than that of WT. Meanwhile, phenotypic observations found that the growth of transgenic plants was inhibited under saline-alkali stress. In conclusion, MhPSY 1 gene involved in carotenoid metabolic pathway plays a negative regulatory role in saline-alkali stress. Key message The gene MhPSY1, which was significantly expressed under saline-alkali stress, was cloned andtransformed into Arabidopsis and apple calli, and it was found that MhPSY1 gene negativelyregulated salt-alkali stress