A new study has traced the mechanism in which PIMT, a protein repairing enzyme maintains seed vigour and longevity in rice.
This research carried out by National Institute of Plant Genome Research (NIPGR) could help as a tool for improvement of such qualities during dehydrated storage of this global food crops. Rice seeds are sensitive to aging and deteriorate on storage, particularly in humid and tropical climatic conditions. Therefore, an improvement in seed longevity and storability will have a huge impact on the agricultural economy.
While PIMT (Protein l-Isoaspartyl O-Methyl Transferase), is known for its capability to repair protein and increase seed vigour and longevity, the regulation of the different forms of the same protein coded from the same gene and the mechanism in which improvement of seed vigour and longevity are largely unknown.
The new paper published in the journal New Phytologist on February 3, 2016 suggests that a PIMT mediated protein repair mechanism is initiated during seed development and increase progressively with each form of the protein playing a distinct, yet co-ordinated role. The study also highlight the possibility that PIMT repairs anti-oxidative enzymes and proteins which restrict biological operations like reactive oxidative species (ROS) accumulation, lipid peroxidation thus contributing to seed vigour and longevity.
The team of scientists from National Institute of Plant Genome Research analysed the accumulation of isoAsp, a form of PIMT in different organs and found that it was highly concentrated in seed followed by the flower. Considerable isoAsp accumulation was observed in vegetative organs, particularly the leaf. It was particularly high during the late maturation stage and in mature dry seeds and also when the mature pollen is abundant. However, it was much lower after 24 hrs of seed imbibation.
They also found that the OSPIMT isoforms are also differentially accumulated during maturation and desiccation when the potential for deleterious isoASP residues increases sharply. The scientists also showed that transgenic rice overexpressing OsPIMTs exhibited improved seed vigour and longevity.
The exploitation of such PIMT-mediated improvement in seed vigor and longevity in rice cultivars can help the agricultural economy.