Phenotypic Plasticity in Morphological Traits of Abelmoschus esculentus L. Induced by Histone Deacetylase Inhibitor, Trichostatin A

Epigenetic changes such as DNA methylation and histone modifications, when meiotically inherited across generations, can act as a stable evolutionary force that is independent of any accompanying DNA mutations. Certain histone deacetylase (HDAC)-inhibiting chemicals such as Trichostatin A (TSA) and sodium butyrate are known to regulate the total acetylated histones in the genome, which is important for regulating the expression of various traits in all organisms. This study investigated all morphological variations in traits of Abelmoschus esculentus L. (okra) induced by different doses of Trichostatin A in a popular okra variety, Arka Abhay. Two sets of seeds were treated with two doses (0.4 µM and 1.2 µM) of TSA and were incubated in the chemical for three and five days, respectively, to record the effects of dose and incubation periods on various agronomic characters of okra. The treatment of TSA had a negative impact on the majority of the characters under evaluation. Total seedlings emerged, and mean shoot and root length were retarded following the TSA treatment. Extremely dwarfed plants with malformed leaves and flowers were a common observation. Pollen sterility combined with distortion of the reproductive whorls of the flowers were particularly pronounced at high doses with a prolonged incubation period. Treated plants had a significantly delayed first flowering and produced short fruits with altered morphology. Variations in seeds with respect to the number, colour and size were also recorded. Total reduction with respect to seedling parameters, total pollen production, the number of fertile pollens, plant height and other damaging effects on leaves, flowers, fruits and seeds increased as the dose and incubation period increased. Statistical analysis revealed the significant negative effect of TSA treatments on plant height, the number of ridges and locules per fruit, number of seeds per fruit and test weight. The treatment, 1.2 µM Trichostatin A incubated for three days, showed a remarkable difference as traits such as total field emergence, seedling parameters and days to first flowering plant height, number of seeds per fruit and test weight deviated from the expected trend of decreasing growth parameters as the dose and incubation period increased. The study further revealed that the treatment (1.2 µM TSA incubated for three days) can be suggested for use in okra to induce epigenetic variations without significantly compromising the growth and vigour parameters of okra.