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Fighting a Mighty Foe: Marker-Assisted Breeding to the Rescue
Downy mildew is a disease caused by the fungus, Sclerospora graminicola. Once infected, pearl millet plants are stunted, grain formation fails, and the plants die spelling misery for thousands of poor farmers who rely on this hardy crop for food, income, and nutrition security. In years when disease attacks were severe, over 30 percent of millet harvests were lost.
Now pearl millet farmers in the semi-arid states of Haryana and Rajasthan, India, need not fear this disease thanks to HHB 67-2, a new pearl millet hybrid that is resistant to downy mildew (DM) disease. The variety was jointly developed by ICRISAT in partnership with Haryana Agricultural University (HAU).
“This significant breakthrough is a result of ICRISAT’s cutting edge scientific research and effective partnerships,” says William Dar, Director General, ICRISAT. “The new hybrid brings additional benefits to farmers, even while retaining the desirable qualities of earlier popular hybrids.”
The new hybrid HHB 67-2 is an improved version of the popular pearl millet hybrid HHB 67, which again was a result of collaborative research between ICRISAT and HAU. Tom Hash, ICRISAT scientist said that the new hybrid is the culmination of over 15 years of dedicated work, generously supported by the UK Department for International Development (DfID).
ICRISAT used marker-assisted and conventional breeding techniques to improve resistance in the parental lines of the original hybrid. The gene for downy mildew resistance was added to the male parent, H 77/833-2, through marker-assisted breeding using ICRISAT elite parent ICMP 451 as the resistance gene donor.
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Haryana farmers in field trials of the new hybrid HHB 67-2. |
An HAU doctoral student, working closely with the ICRISAT team, conducted the marker-assisted backcross breeding work. The gene for downy mildew resistance was added to the female parent, 843A/B, from ICRISAT line ICML 22 through conventional backcross breeding. Finally, the All India Coordinated Pearl Millet Improvement Project (AICPMIP) field-tested the new hybrid at various locations over the past three rainy seasons.
By using advanced molecular marker-assisted selection techniques, the male parent for HHB 67-2 was developed in one-third the time required for the developing the female parent by conventional methods. By identifying and marking the gene responsible for DM resistance in ICMP 451, breeders were able to check whether the gene had transferred to the next generation in the progeny of crosses between ICMP 451 and the male parent of HHB 67. The advantage of using molecular marker technology is that gene presence can be tested even while the next generation is a seedling, saving precious breeding time. In conventional breeding, the presence of a gene can be verified only after the plant grows to maturity and seed from an individual plant is sown to screen for the DM resistant character.
ICRISAT has produced breeder seed of the parental lines of HHB 67–2, which can now be used to multiply the hybrid, and this will be supplied to seed multiplication agencies. Thanks to these cooperative efforts, farmers are getting respite from a mighty foe.
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