Category: Food

Scientists a step closer to developing disease resistant maize variety

Scientists at International Maize and Wheat Improvement Center (CIMMYT) at Hyderabad, India in collaboration with their counterparts in Nairobi, Kenya have conducted a genome-wide association study (GWAS) to identify regions in maize DNA that confer improved resistance to sorghum downy mildew disease in maize. SDM is an important foliar disease of maize caused by the fungus, Peronosclerospora sorghi.

We all relish corn- be it as popcorn, sweet corn or the breakfast staple- corn flakes. Maize or the Corn is the world’s leading cereal grain with a total production that has surpassed wheat or rice and India is one of the eight major maize growing countries in Asia. Unfortunately, during the monsoon season, the total productivity is limited due to the susceptibility to a number of diseases like downy mildews (DM), leaf blights, rusts, stalk rots and ear rots with DM spread throughout Asia.

In this report, the group conducted a genome-wide association study (GWAS) for sorghum downy mildew (SDM) resistance in a panel of 368 inbred lines adapted to the Asian tropics. Along with previously reported regions conferring resistance to SDM, they identified novel SNPs in the genome that are important. SNPs or Single Nucleotide Polymorphism is a variation in a single nucleotide (basic unit of the DNA) that occurs at a specific location in the genetic code and each change or variation is present to some degree within a population.

Six of these SNPs belong to significant regions reported to be associated with DM resistance and could be useful in maize breeding programs to develop DM-resistant maize varieties. The study was led by Dr. Sudha K Nair, Senior Molecular Geneticist, CIMMYT, Hyderabad.

“Downy mildew being a devastating problem for the entire Asian maize cultivation, understanding the genetics of the trait, and using that in breeding for resistant varieties is the most ecologically efficient way of managing the disease. It is for the first time that, a panel of about 400 maize inbred lines is being used in a genome-wide association study using high density, genome-wide SNP markers of more than 300,000 for identifying genomic regions responsible for the quantitative resistance towards downy mildew in maize”, explained Dr. Nair.

Metalaxyl, a chemical that is used to kill the fungus causing DM, is less effective now as the fungus has developed resistance to it owing to its extensive use. Thus, rather than using chemicals, farmers need a more sustainable and less expensive alternative to combat SDM in maize.

“On the basis of Genome wide association (GWAS), significant number of SNPs and haplotypes observed in Asiatic tropical maize breeding lines wherein eight novel genomic regions associated with Sorghum Downy Mildew (SDM) resistance were reported for the first time in the present study. In addition, ten marker-phenotypic trait associations identified were co-located within the genes associated with SDM resistance that could provide critical information for future empirical studies for improvement of breeding programs in maize”, explained Dr. Vishal Acharya, Scientist, Functional Genomics and Complex System Lab at CSIR-Institute of Himalayan Bioresource Technology, Palampur. Dr. Acharya is not connected with the study.

Dr. Nair and her team is quite hopeful, “We are in the process of validating the resistance-associated SNP markers in our maize breeding program, which could then be shared with all our partners, both public and private, for routine use in maize breeding programs in the region”.

“The International Maize and Wheat Improvement Center, known by its Spanish acronym, CIMMYT®, is one of the 15 independent, international, non-profit agricultural research organizations that make up the CGIAR (Consultative group on International Agricultural Research) with partners in over 100 countries (www.cimmyt.org). Head-quartered in Mexico, Hyderabad is the hub for CIMMYT’s tropical maize improvement activities for Asia”, Dr. S K Nair added.

The team comprised of Zerka Rashid, Pradeep Kumar Singh, Hindu Vemuri, Pervez Haider Zaidi, and Sudha Krishnan Nair from CIMMYT, Hyderabad and Boddupalli Maruthi Prasanna, Program Director, Global Maize Program from CIMMYT, Nairobi. The study was published in journal Scientific Reports.

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Spices- a secret weapon in the war against Cancer

Who doesn’t love spices? Well, now we have another reason to enjoy them a little more often!

Scientists at Rajiv Gandhi Centre for Biotechnology, Kerala and Manipal University, Karnataka show Cardamonin, a chemical found in the Cardamom spice, and many other edible plants like ginger, peppercorn, and more to be effective in preventing and controlling colorectal cancer in mice.

 

The team led by Dr. Harikumar performed studies on Azoxymethane (AOM) induced mouse model of colorectal cancer (CRC) and human cancer cell lines- widely established systems for such studies.

 

Colorectal cancer, cancer of the colon or the rectum, is currently the third most common cause of cancer in men and second most in women. Our age, diet and lifestyle habits are to be blamed for it.

 

Cardamonin is effective both ways, given as a protective agent before the development of cancer as a dietary intervention or even started after the development of CRC, the study showed. They figured out the mechanism of action of this phytochemical, a plant derived chemical and identified its role in altering the MicroRNAs or miRNAs in the cell.

 

These miRNAs are short stretches of genetic material (RNA) that do not code for a protein but have regulatory functions.

“Cardamonin modulates certain miRNAs that collectively regulate the reactive oxygen (ROS) production”, explains Dr. Harikumar.

ROS are chemicals that when produced, lead to cell death; cardamonin increases ROS production which results in the death of unwanted cancer cells.

 

The team is the first in showing the role of miRNAs in AOM induced colorectal cancer.

“Along with further identifying the critical miRNAs which regulate ROS dependent genes, we are also interested in checking the synergy between the cardamonin and FDA approved chemotherapeutic drugs for a possible combination therapy. Exploring certain chemically synthesized analogs of cardamonin with increased cytotoxicity is one of our prime focuses”, Dr. Harikumar says.

 

 

The work was a team effort of Shirley James, Jayasekharan S. Aparna, Aswathy Mary Paul, Manendra Babu Lankadasari, Sabira Mohammed, Valsalakumari S. Binu, Thankayyan R. Santhoshkumar, Girijadevi Reshmi & Kuzhuvelil B. Harikumar. The findings are published in Scientific Reports.

New method developed to prepare milk protein-vitamin A complexes

Low-fat and fat-free foods are gaining popularity lately. Although restricting the amount of fat in the diet is good for health, paradoxically, it also results in loss of fat soluble vitamins and essential fatty acids leading to a myriad of deficiencies. The challenge then becomes the addition of fat soluble nutrients to such fat-free or low-fat foods to make up for these deficiencies.

Scientists at the National Dairy Research Institute (NDRI), Karnal, Haryana have come up with a method to enhance the nutritional content of fat-free milk by preparing Vitamin-A and Milk Protein complexes.

Vitamin-A is one of the four fat-soluble essential vitamins, the others being D, E and K. The deficiency of Vitamin-A, which is the leading cause of preventable childhood blindness is a major public health problem in India.

Dr. Arora and his team of researchers modified casein, the major protein present in milk, with a chemical called succinic anhydride (SA) and prepared succinylated casein- Vit A complexes. They tried different combinations and found sodium caseinate-Vit A and succinylated sodium caseinate-Vit A complexes had high Vitamin-A binding ability and solubility.

SA is classified under the ‘generally recognized as safe (GRAS)’ category by the United States Food and Drug Administration (USFDA) thus modifications of casein using SA are considered safe for human consumption.

They suggest that casein owing to its unique properties can be easily used as a delivery vehicle for Vitamin-A in milk.

 

“FSSAI (Food Safety and Standards Authority of India) has approved the addition of vitamins A and D to milk. These vitamins are being used for fortifying milk by Mother Dairy, Amul and many state cooperatives at the moment”, Dr. Arora commented. He further added, “addition of minerals would be the next step”. He assures us that such fortified foods are no longer a fantasy and that these improvements will be done incrementally.

 

Such strategies involving the fortification of staple foods like milk, rice, salt, etc. are the most important tools in India’s arsenal for the fight against malnutrition.

The team led by Dr. Sumit Arora included Chitra Gupta, M.A. Syama and Apurva Sharma at the Dairy Chemistry Division, National Dairy Research Institute (NDRI), Karnal, Haryana. This work was published in the journal Food Chemistry and was financially supported by Department of Biotechnology (DBT), Government of India.