Scientists at the Jawaharlal Nehru Tropical Botanic Garden and Research Institute (JNTBGRI) at Palode near here are racing against time to save a rare type of wild black pepper from being wiped out of existence.
The institute has taken up vegetative propagation of the wild variety that is threatened by unsustainable extraction from its natural habitat in the remote forests of the south Western Ghats. Characterised by a lemon-scented leaf, the genetic variant named Piper nigrum L. ‘PMM’ has been found to possess unique properties that impart a high commercial potential.
Tests carried out at the institute have revealed that the fruits of the species possess a significantly higher yield of essential oils and contain a larger percentage of piperine (the constituent that imparts the pungent taste). The scientists are trying to cross- pollinate the wild species with cultivated varieties for genetic improvement of the spice crop.
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The second generation of the vines collected from the wild and planted at the institute have also been found to possess the same properties. Chemical analysis tests revealed that the unique lemon scent of the leaves is due to the presence of aroma chemicals such as citral derivatives and bicyclogermacrene while the high pungency of the fruits is attributed to the elevated level of piperine.
“The south Western Ghats, one of the biodiversity hotspots in the world, is the centre of origin and diversity of pepper. However, reckless harvesting from the wild has led to heavy gene erosion. There have been reports of tribes pulling out the vines by their roots for sale to middlemen”, says K.B.Rameshkumar, scientist, Department of Phytochemistry, JNTBGRI.
It was in 2008 that a team of scientists from the institute stumbled upon the wild variety of pepper in the Western Ghats during a plant exploration mission. Stem cuttings were taken back to the experimental garden at the JNTBGRI for planting and propagation.
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Considering its coexistence with other types of pepper in the wild, the scientists have come to the conclusion that the unique properties of Piper nigrum L. ‘PMM’ are genetically determined and not just due to the influence of the environment. They feel that the genetic variation could have accumulated as a result of inter-crossing, segregation and random mutations over a period of time.
Tests carried out at the institute revealed that the fruits from the wild variety yielded 9 per cent oil compared to 2.8 per cent for P. nigrum ‘Ampirian,’ the commonly cultivated type. The piperine content in the fruits of PMM was as high as 9.9 per cent while it was only 4.8 per cent in the cultivar.
“The international market for black pepper is quality-oriented. This is where genetic variants with characteristic attributes assume significance in plant improvement”, says P.J. Mathew, Head, Division of Plant Genetic Resources. “Inventorisation, and mapping the geographic origin of wild varieties are to be carried out urgently to ensure conservation and sustainable utilisation of the resource”.