Soybean autotoxicity: Effects of m-hydroxy-phenylacetic acid on cell ultrastructural changes and gene expression in soybean roots

The application of m-hydroxy-phenylacelic acid (MHPA), significantly inhibited the radicle growth and root tips became thicker and brownish ill colour than untreated control. Transmission electron microscopy analysis showed that MHPA adversely affected the soybean root tip, leading to sparse cytoplasm and fewer organelles in root meristematic cell, cell vacuolation and poorly developed irregular amyloplasts in root columella cell. A total of 33 differentially displayed cDNA fragments were found between the MHPA treated and control samples and 6 differential displayed cDNA fragments were observed after the subsequent DDRT-PCR reactions on extracted RNA. Results from RT-PCR confirmed two differential expressions, (i). one down-regulated gene (S385) and (ii). one up-regulated gene (S452), these expressed approximate half-fold and 5-folds over the control plants, respectively.