A team of plant scientists jointly led by Dr Rahul Kumar from the University of Hyderabad (UoH) and Professor Arun K Sharma from the University of Delhi (DU) has identified a conserved mechanism that controls tomato fruit ripening by inhibiting ethylene biosynthesis. A press statement from UoH claims the collaborative research to be a "breakthrough".
The study can be used to improve ripening traits in other fleshy fruits. Titled Elevated methylglyoxal levels inhibit tomato fruit ripening by preventing ethylene biosynthesis, the research paper, authored by Priya Gambhir, a PhD scholar from DU, and her team, was recently published in Plant Physiology, a leading scientific journal issued by the American Society of Plant Biologists, US.
The obligatory role of ethylene in inducing ripening in fleshy fruits is well known, due to which its biosynthesis and signalling pathways can be studied well in fleshy fruits such as tomatoes. However, a complete understanding of the genetic regulatory mechanisms controlling the ripening process remains to be fully understood, the press statement explains.
"Improved knowledge of such molecular regulatory events is crucial to develop effective biotechnological strategies for improving ripening traits such as fruit flavour, pigment accumulation, and shelf-life. Varieties with prolonged shelf-life can minimize the post-harvest loss of fruits and vegetables during transport and storage. Such superior varieties will also benefit farmers," it adds.
The team found that several non-ripening mutants which do not ripe normally accumulate high levels of Methylglyoxal (MG), a toxic compound produced as a byproduct of several cellular processes. MG is known to interfere with protein function by non-enzymatically glycating them. The team developed both overexpression and gene-silenced lines of one of the ripening-associate glyoxalase enzymes (SlGLYI4) and demonstrated that silencing this gene led to drastic MG overaccumulation at ripening stages.
This suggests that a tightly regulated MG detoxification process is crucial for the normal ripening process. "At the onset of ripening, SlGLYI4 curtails the enhanced levels of MG associated with the respiratory burst and several other metabolic activities so that the ripening can proceed in a normal way. In the absence of the glyoxalase detoxification system at the time of fruit maturation, soaring amounts of MG can potentially inhibit the ethylene biosynthetic pathway at multiple levels, thereby leading to fruits' incompetency to ripen," the study concludes, according to the statement.
