A team of researchers in India has bettered an immensely popular pearl millet hybrid, HHB 67 Improved, endowing it with 58% higher resistance to downy mildew (DM) disease. The latest improvement has also increased the hybrid’s blast resistance by 12%, grain yield by 15% and dry fodder yield by 21% while retaining its hallmark early-maturity trait.
Researchers at ICRISAT partnered with Chaudhary Charan Singh Haryana Agricultural University (CCSHAU) and ICAR-All India Coordinated Research Project on Pearl Millet (AICRP-PM) for the second cycle improvement of HHB 67 Improved hybrid. Using genome-wide simple sequence repeat (SSR) DNA markers, three DM resistance loci (quantitative trait loci or QTLs) were moved to the male parent of HHB 67 Improved. Scientists at ICRISAT’s Center of Excellence in Genomics and System Biology, Genetic Gains Research Program, stacked the three DM resistance QTLs from different chromosomes (linkage groups 3, 4 and 6) of the donor parents.
The latest improvement has been christened HHB 67 Improved 2-7 (meaning HHB 67 Improved second cycle improvement, 7th version). It was tested in Essentially Derived Variety multi-location, multiyear trials of AICRP-PM in A1 and A (dry) zones of India.
The need for improvement
HHB 67 pearl millet hybrid was released in 1990 and soon became a farmer-preferred hybrid owing to its extra-early maturity that helped the plant escape end season drought. However, this hybrid became susceptible as the incidence of DM increased in western India, warranting improvement. The HHB 67 Improved, with DM resistance, was released in 2005.
More than two million people enjoy food security due to HHB 67 Improved in India. This extra-early, DM-resistant farmer and consumer-preferred hybrid is grown in more than 800,000 ha out of 7-7.5 million ha in which pearl millet is grown every year. This popular hybrid has helped prevent annual losses of US$ 8 million across Haryana and Rajasthan that DM can cause. However, the typical lifespan of any pearl millet hybrid is not more than 4-5 years before DM catches up.
Of the many versions of the latest improvement that were tested, version 7 performed exceedingly well with significant gains over HHB 67 Improved. Researchers also say that the scientific approach to improvement this time was different and an improvement itself over the last cycle’s approach, where Restriction Fragment Length Polymorphism (RFLP) markers were deployed.
The second cycle version of HHB 67 Improved is being considered for release by ICAR. This improved hybrid may prove a turning point for the dry north and north-western India by boosting food, fodder, nutritional and economic security in these regions.
Written by Dr Rakesh Srivastava, Principal Scientist – Molecular Breeding, Genomics & Trait Discovery.