Tuesday, 19 March 2013

Tomato Engineering - Understanding Fruit Development and Ripening Parameters

Tomato is an important ingredient of many Indian dishes. In many parts of Indian states you can't think of food with tomato. It is consumed in different forms such as tomato sauce, ketchup, condiments, added flavours, salad, etc. In southern part of India tomato-rice (takkali sadam) is one of the popular dish which is prepared adding tomato with rice. It adds sourness to the food and also it is used as base for gravy holding the spices and onion together.
Now the nutritional fact. Tomato contains carbohydrate, protein, vitamins and minerals. It contains vitamin A and C. Iron is the major mineral found in it.
Photo- http://www.magnificentjharkhand.blogspot.com
Some major tomato growing countries are China, USA, Italy, Turkey, India and Egypt. As per Indian Horticulture Database 2011, India ranks second in the area as well as production of Tomato. Some major tomato growing states in India are Andhra Pradesh, Karnatka, Odhisha, Maharashtra, West Bengal, Bihar, Gujrat, Chattishgarh, Tamilnadu and Jharkhand. Although export of tomato has shown a significant increase of 97% from 2007-08 to 2011-12 (source: APEDA) immediate ripening and stoarge are the major hurdles farmers faces after harvesting the crop. In more simplified words productivity is high but cash return is not guaranteed as it cannot be stored for longer period and farmers has no other way than to destroy the crop in the field even. Many a times it is destroyed in local market when no takers or traders are there to purchase the tomatoes from the farmers (photo). 
New research findings published in 'Journal of Experimental Botany' with regard to tomato development and ripening by group of scientists from The Netherland may be the future solutions to this problem. With the help of  'tomato engineering' (genetic engineering of tomato) they are able to identify the components involved in different stages of development of tomato and ripening.
Group headed by Dr. Rudd A de Maagd which includes scientists from four different plant research institutes of The Netherland has identified microRNA (miRNA) targets in tomato fruit development using 'Parallel Analysis of RNA Ends' (PARE). They identified a total of 119 target genes of miRNA. Of these 106 claimed to be new targets.

A microRNA (abbr. miRNA) is a small non-coding RNA molecule (ca. 22 nucleotides) found in plants and animals, which functions in transcriptional and post-transcriptional regulation of gene expression.[for details on miRNA visit  http://en.wikipedia.org/wiki/MicroRNA]
Using the PARE method, they found that miRNAs may regulate initiation of fruit development through miR393 and miR167 targeting of SlTIR1 gene and ARFs genes (putative auxin receptor), respectively.Two Transcription Factors (TFs) that play a major role in regulation of tomato fruit ripening, CNR and AP2a, were known to be a target, or a putative target, of miR156/157 and miR172, respectively. In their study, they confirmed that SlAP2a is indeed a target of miR172 in tomato and, moreover, it was shown that both TF mRNAs are actively targeted during fruit development and ripening.
Overall their findings suggest the important role of miRNAs in tomato fruit development starting from the initiation of the fruit until the final ripe stage. These studies could also be used in breeding programmes aimed at modifying ripening parameters in tomato through natural or induced variation in miRNA expression.

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