Tag Archives: NCL

New mosquito repelling molecule identified

Dr. Aditi Jain

New Delhi: Indian researchers have synthesized a new aromatic molecule that promises to help repel and kill adult female of Aedesaegypti mosquito which is carrier of several disease-causing viruses.

Mosquito bites that result in diseases such as malaria and dengue are a major concern in tropical countries where the temperature allows their easy breeding and transmission.Among these diseases, dengue ranks as the most critical with about 390 million infections occurringevery year. Mosquito nets and repellents can help decreasethe incidence of these diseases. However, mosquitoes are increasingly becoming resistant to pyrethroid-based insect repellents.

A team of researchers at National Chemical Laboratory (NCL), Pune, has synthesized several molecules from two aromatic compounds — noreremophilanes and nardoaristolone B. The compounds are structurally related to nootkatone, which is a natural product extracted from grapes and has earlier been shown to be effective against ticks and mites.

Based on structural similarities, scientists reasoned that the synthesized molecule may show insecticidal and repellent property against mosquitoes too. They tested their efficacy against adult females of Aedesaegyptiand found that one of the molecules, named NDS-100598, exhibited higherrepellence.

In laboratory experiments, researchers tested this molecule by applying a small amount of the chemical on muslin cloth placed on glove (which was worn by a volunteer). It was observed that mosquitoes did not bite when 0.25 milligram of this molecule was applied per square cmof surface.

“We have done preliminary acute dermal toxicity tests on rats and acute dermal irritation test on rabbits which suggest that the molecule is safe.However, detailed toxicity studies still needs to be conducted,”commented Dr. D. Srinivasa Reddy, a member of the research team, while talking to India Science Wire.

The researchers are in discussion with some leading companies for commercialization of this insect repellent molecule.The results of the study have been published in journal ACS Omega. The research team includedKishor L. Handore, Hanuman P. Kalmode, Shahebaz Sayyad, B. Seetharamsingh,Ganesh Gathalkar, SarangPadole, Pushpa V. Pawar, Mary Joseph, and Avalokiteswar Sen, apart from Dr. Reddy. (India Science Wire)

Twitter handle:@AditiJain1987

Wild tomatoes can help in making commercial varieties disease-free

Vaishali Lavekar

Pune: From soup and salads, tomato serves as a primary ingredient in Indian food. It is nutritious, loaded with antioxidants and
vitamins. But keeping tomatoes free from ‘early blight’ disease is a challenge for farmers.

Now a group of Indian scientists has found a way to develop tomatoes resistant to the most common disease – early blight (EB). They have identified biochemical and molecular mechanisms in wild tomato that makes them resistant to early blight. This knowledge can be used to improve commercial varieties and develop tomato cultivars resistant to EB in future.

The study has been published in journal Plant Molecular Biology recently by scientists from the National Chemical Laboratory, Savitribai Phule Pune University and Weizmann Institute of Science, Israel.

The early blight disease is caused by a fungus, Alternaria soloni , and it can lead to 35 to 78% yield loss. It manifests in symptoms like fruit rot, leaf spots and stem lesions. Commercially planted cultivars have low levels of resistance towards early blight than wild varieties. “We studied consequences of fungal infection in wild and cultivated varieties at biochemical and molecular level, and have identified two biosynthetic pathways controlling early blight in tomato leaves – SGA (steroid glycol-alkaloid) and PB (phenylpropanoid biosynthesis),” explained Dr Ashok Giri, one of the team members at NCL, Pune.

Once infected, tomato plant produces metabolites known as phytoalexins which are connected with SGA pathway. "The higher levels of phytoalexins are found in in resistant plant than sensitive one. The PB pathway leads to increased lignin
biosynthesis which was found to be enhanced in resistant tomato plants. When these metabolite substances are tested, it was found that they possess an antifungal property,” explained Balkrishna Shinde, the lead author.

Further studies showed that there was higher expression of a gene, GAME2, in resistant tomato and negligible in sensitive cultivars. Transcripts of GAME2 are predicted to be responsible for conversion of beta-tomatine to alpha-tomatine. Beta -tomatine is non-toxic to pathogen whereas alpha-tomatine showed strong inhibitory effect on fungal growth.

“This means GAME2 gene expression contributes early blight resistance in wild tomato. We are focusing on the mechanistic basis that might occur through regulation of gene expression by specific transcription factors,” said Dr. Giri.

Researchers also predicted a connection between lignin biosynthesis and A. solani invasion to plants. Resistance variety shows higher levels of rutin, one of the metabolite of PB pathway, which demonstrates fungi-toxic effects.

The research team included Balkrishna Shinde, Khalid Hussain, Sayantan Panda and Prof Avinash Kamble (Savitribai Phule Pune University); Dr. Bhushan Dholakia and Dr. Ashok Giri (National Chemical Laboratory, Pune); Dr. Sagit Meir, Dr. Ilana Rogachev and Dr. Asaph Aharoni (Weizmann Institute of Science, Israel). (India Science Wire)
tomato, early blight, wild tomato, CSIR, NCL