July 25, 2022

IITA scientist breeds more resilient yam species in West Africa

Agribusiness: FG builds capacity of extension workers on yam production

By Sola Ogundipe

A  MOLECULAR geneticist at the International Institute of Tropical Agriculture, IITA,  Ibadan, Oyo State, Nigeria, Dr. Ranjana Bhattacharjee, who is helping to boost food security in Africa, has won the 2022 Illumina Agricultural Grant for genomics research to breed resilience in West African yam.

Yam, the king of crops and  the fourth most utilised root and tuber crop—after potatoes, cassavas, and sweet potatoes, is a food staple  in Nigeria and across West Africa.

Bhattacharjee and her team are receiving the support to enable the sequencing of the genes of cultivated and wild yam species and to determine the traits that can increase disease resistance and yields of the crop.  

A statement from Illumina noted that Bhattacharjee is using whole-genome sequencing to understand the crop’s evolution and generate improved varieties, with support  from the 2022 Illumina Agricultural Greater Good grant.

“The world’s largest producer  is the West African “yam belt” stretching from southeast Guinea to northwest Cameroon, with Nigeria contributing the highest yield.

“The yam not only helps provide food security and nutrition, it’s also an integral socio-cultural symbol—yams often play an important role in wedding ceremonies and festivals.

“When Dr. Ranjana Bhattacharjee joined the International Institute of Tropical Agriculture (IITA) in Ibadan, Nigeria, in 2009, the knowledge on yam genomics was limited due to lack of funding. Bhattacharjee, however, recognised the nutritional and economic importance of these starchy tubers and became motivated to carry out in-depth genomics-assisted research on them.”
Illumina said since 2011, it has been recognising research proposals that will increase the sustainability and productivity of important food commodities and livestock species.

“As the 2022 grant winner, Bhattacharjee will be able to do whole-genome sequencing of about 1,000 Guinea yam samples on the Illumina NovaSeqTM 6000 System. This is one of the largest numbers of yam samples ever sequenced.

“Bhattacharjee and her colleagues are eager to use this grant to understand the genetic relationships between different species (both cultivated and wild) of yams in West Africa, and to study specific genes of the crop that can confer disease resistance, resilience, and higher yield. The sequencing data will be made public on IITA’s open-access platforms.”

In a response, Bhattacharjee  said genomic sequencing is revolutionising the agricultural sector at the moment, even as she  hopes that with this sequencing project, the amount of knowledge generated will change the status of the orphan crop.

The researcher hopes the partnership with Illumina will ultimately halve the time it takes to develop a new cultivar and help identify traits that will provide more clues toward improving such an important crop through comparative genomics.

“At the end of the day, the goal is to make a crop more resilient,” she remarked.

When the reserves of domesticated yams become scarce, yam farmers and breeders often go foraging for wild varieties, which they then cross with farmed or cultivated varieties.

Dr. Robert Asiedu, former yam breeder and director emeritus of IITA-West Africa, describes this process as laborious, and one that has not been optimised.

Asiedu explained that although yams can grow well without fertilizers or herbicides, they must be staked, mounded, and routinely monitored for weeds even as farmers and breeders must wait about a decade to develop a new variety or hybrid.

“We need modern, high-throughput tools and technologies to try and transfer targeted characteristics from one species to the other,” Asiedu noted.