Fine mapping of male sterility gene reveals defective pollen starch accumulation in barley

Barley (Hordeum vulgare L.), the world's fourth most cultivated cereal crop, serves as a key raw material for the brewing industry and a significant feed source for livestock. Exploiting heterosis is a strategy for boosting crop yields, and male sterility genes and their corresponding mutants are valuable genetic resources for facilitating hybrid seed production. Hence, identifying novel male sterility genes and developing efficient hybrid seed production systems are important for overcoming yield limitations in cereals.

A team of researchers from China and the US identified and characterized a novel EMS-induced barley male-sterile mutant (N13401). Their findings are published in the Journal of Integrative Agriculture.

"We isolated a completely male sterile mutant, designated N13401, from an ethyl methanesulfonate (EMS)-mutagenized population of the barley cultivar 'Tamalpais'," explains senior and co-corresponding author Prof. Fei Ni from Shandong Agricultural University.

The msg_N13401locus was mapped by the researchers using a method that combined BSR-Seq with forward genetics. However, fine mapping was hindered by insufficient polymorphisms between cultivated barley varieties, resulting from domestication-induced genetic homogenization.

"To overcome this challenge, we exploited the extensive genetic variation that exists between undomesticated wild barley and cultivated barley and successfully constructed a new F₂ mapping population," Ni adds, "Leveraging the abundant polymorphisms within this population, we ultimately fine-mapped msg_N13401 to a 576.9 kb interval on chromosome 2H."

The team's findings validated an effective strategy for overcoming insufficient polymorphisms, that is, introducing wild relatives to establish an additional mapping population. "Using DNA resequencing, we successfully identified three candidate genes within the target interval which may be involved in proline biosynthesis regulation, DNA binding, or vacuolar metal transport," says co-corresponding author Juan Qi.

Notably, these candidates do not overlap with known male sterility genes, confirming msg_N13401 as a novel locus. "This discovery provides valuable genetic material for an in-depth dissection of its molecular mechanism and will accelerate the process of hybrid barley breeding," Qi adds.

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Contact the author: #Correspondence Fei Ni, E-mail: nifei1998@sdau.edu.cn; Juan Qi, E-mail: qijuan@sdau.edu.cn

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