‘Tweaking genes could help extend shelf-life of mangoes, boost exports’

Kolkata, Sep 18 (IANS) Wastage of mangoes cultivated in India, the world’s top producer, due to flawed post-harvest practices can be countered by tweaking certain genes in the “King of Fruits”, say Indian researchers who have identified the ones most prominently involved in ripening of the juicy ‘dashehri’ variety.

India accounts for 42.06 percent of world’s mango production but about a quarter is wasted due to faulty practices during harvesting, packaging and storage.

The development by the team from CSIR-National Botanical Research Institute (NBRI), Lucknow, could help change this and drive an uptick in export of the fruit in future by increasing shelf-life through genetic manipulation or by marker-assisted breeding strategies wherein one can quickly screen and spot whether a favourable trait has been introduced from one mango variety into another.

“Every trait in a plant is determined by genes, the place and timing of their expression and the extent to which these are expressed,” Vidhu Sane of NBRI, told IANS.

Gene expression is the process by which ‘genetic’ instructions are used to synthesise gene products.

“For instance, genes responsible for ripening-related traits such as aroma, taste, colour, softening and the like increase during ripening. Our studies tell us which genes are most prominently involved in these changes,” explained Sane.

India exported only 41,000 tonnes of mangoes in 2013-14 as fresh fruit, accounting for about 0.4 percent of production.

“Its dominance as the largest producer is poorly translated into international trade. The practical applications of our study are manipulating the genes that are responsible for loss of quality in mangoes which could increase their shelf-life,” said Sane.

To drive home the point, Sane cited the dashehri variety, the subject of the study, as an example.

Dashehri is very popular in northern India as it is fibreless, delicious in taste with a mild aroma and has very high pulp content.

But there is a major roadblock when it comes to exports: The fruit’s rapid and uneven ripening. It ripens from the stone towards the periphery.

“There is jelly formation in the pulp near the stone, at late ripe stage, although it looks firm and good from outside. By identifying the genes responsible for this and then crossing with varieties where the expression of these genes is reduced, one can develop varieties where jelly formation is reduced and shelf-life is increased. Alternatively, genetic manipulation of these genes may also suppress jelly formation in the centre and increase the shelf-life,” said Sane.

The team turned to the transcriptome — the collection of RNA read-outs that are expressed by a cell’s active genes (in DNA). These blueprints are needed to translate the information stored in the DNA into functional gene products such as proteins, including the hormone involved in the ripening process.

They sequenced the transcriptomes during the dashehri’s unripe and ripe stages.

“This tells us how many different genes are being expressed at a time and the changes in their levels as the fruit ripens,” the scientist spoke of the analysis published in Scientific Reports in September.

“By extending these studies to other mango varieties, as is being done in our lab, one can identify the differences in genes which are responsible for the varietal changes in ripening parameters in varieties like dashehri, alphonso, banganapalli, ratna, langra and kesar et al and this can help in developing markers for breeding,” Sane added.

(Sahana Ghosh can be contacted at sahana.g@ians.in)

–IANS

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