Manipulating heat, drought tolerance in cowpeas

New and improved varieties of cowpeas have numerous adaptive traits of agronomic importance, such as 60-70 day maturity, drought tolerance, heat tolerance, aphid resistance and low phosphorus tolerance, said Dr. Meiping Zhang, Texas A&M AgriLife Research associate research scientist in College Station.

Under a National Institute for Food and Agriculture grant of $500,000, Zhang and other Texas A&M scientists will take advantage of the recently developed DNA sequencing technology to map and ultimately clone the genes controlling drought and heat tolerance for molecular studies and deployment of these genes in other crops, she said.

Joining Zhang on the project are Dr. Hongbin Zhang, Texas A&M professor of plant genomics and systems biology and director of the Laboratory for Plant Genomics and Molecular Genetics; Dr. B.B. Singh, a visiting scholar and cowpea breeder with the Texas A&M soil and crop sciences department; and Dr. Dirk Hays, Texas A&M associate professor of physiological and molecular genetics, all in College Station.

The goal of the study is to develop single nucleotide polymorphisms or SNP markers, the latest DNA marker technology, enabling efficient manipulation of heat and drought tolerances in cowpeas and related species, Zhang said.

Cowpeas were chosen for the study because they are a high protein grain, vegetable, fodder and high nitrogen-fixing legume that can be intercropped with corn, cotton and other crops in many countries, including the U.S., Zhang said.

"We know it is highly tolerant to drought, heat and several other biotic and abiotic stresses," she said. "This research will use high-throughput site-associated DNA sequencing to map the genes controlling drought and heat tolerance and to develop SNP markers, enabling efficient manipulation of heat and drought tolerances in cowpea and related species."

Zhang said they have already developed a mapping population of 110 recombinant inbred lines from a cross of two cowpea lines that are highly tolerant or susceptible to both drought and high temperature. This population is being augmented into more than 200 recombinant inbred lines for the new project.

"We will not only map drought and heat tolerant genes, but also develop a platform for mapping genes controlling several other biotic and abiotic stress tolerances such as aphid resistance and low phosphorus tolerance, both of which are also of extreme significance for agricultural production of many crops."

The drought and heat tolerant genes, once defined and cloned, will significantly advance understanding of the molecular basis underlying plant tolerances to these stresses, Zhang said.

This will help researchers design tools to effectively combine multiple traits into new cultivars adapted to the globally changing climate in this and related crops, thus supporting the long-term genetic improvement and sustainability of U.S. agriculture and food systems, she said.