Molecular identification of the wheat male fertility gene Ms1 and its prospects for hybrid breeding

Abstract

The current rate of yield gain in crops is insufficient to meet the predicted demands. Capturing the yield boost from heterosis is one of the few technologies that offers rapid gain. Hybrids are widely used for cereals, maize and rice, but it has been a challenge to develop a viable hybrid system for bread wheat due to the wheat genome complexity, which is both large and hexaploid. Wheat is our most widely grown crop providing 20% of the calories for humans. Here, we describe the identification of Ms1, a gene proposed for use in large-scale, low-cost production of male-sterile (ms) female lines necessary for hybrid wheat seed production. We show that Ms1 completely restores fertility to ms1d, and encodes a glycosylphosphatidylinositol-anchored lipid transfer protein, necessary for pollen exine development. This represents a key step towards developing a robust hybridization platform in wheat.

CRISPR/Cas9‐mediated knockout of Ms1 enables the rapid generation of male‐sterile hexaploid wheat lines for use in hybrid seed production

“…The targeted mutations carried by GL353‐119 were inherited in a Mendelian fashion, and completely male‐sterile (+1/+1) mutants were recovered in the T 2 and T 3 generations, along with fully fertile +1/WT and WT/WT plants. These results are consistent with previous reports of male sterility in EMS‐derived Ms1 knockout mutants (Tucker et al ., ; Wang et al ., ). Furthermore, we obtained four T 2 knockout mutants that were apparently non‐transgenic based on fluorescence microscopy and PCR assays.…”

Wheat ms5 male‐sterility is induced by recessive homoeologous A and D genome non‐specific lipid transfer proteins

“…Furthermore, the Ms3 sterility phenotype is temperature‐dependent (Maan and Williams, ), impeding its widespread implementation for hybrid seed production. The recent molecular identification of ms1 (Tucker et al ., ; Wang et al ., ) confirms its high suitability for use in a GMS hybrid production system, but the identity of ms5 and its potential for similar use has not previously been reported.…”

Identification of genes involved in male sterility in wheat (Triticum aestivum L.) which could be used in a genic hybrid breeding system

“…Which is part of a suite of stable genic male sterility (GMS) loci ( MS1–MS5 ) identified thus far in wheat (Driscoll, ; Fossati & Ingold, ; Pugsley & Oram, ; Sasakuma, Maan, & Williams, ; Zhou, Wang, Feng, Ji, & Wang, ), the five mutants identified contained ms1 and ms5 which are recessive mutants (Klindworth, Williams, & Maan, ; Sasakuma et al, ), and Ms2 , Ms3 , and Ms4 which are dominant mutants (Maan, Carlson, Williams, & Yang, ; Maan & Kianian, ; Qi & Gill, ). Currently, only one dominant gene, Ms2 , and one recessive mutant have been cloned in wheat (Ni et al, ; Tucker, Baumann, & Kouidri, ; Wang et al, ; Xia et al, ), with Ms2 mutants being widely used for wheat breeding and potentially for hybrid wheat breeding (Ni et al, ). Other genes involved in male sterility in wheat include the genes Ms26 and Ms45 which are involved in the formation of the pollen cell wall similar to ms1 which is a transcription factor and regulates the post‐meiotic development of the anther (Dong et al, ; Singh, Kumar, Thilges, Cho, & Cigan, ; Tucker et al, ; Wang et al, ).…”

“…Currently, only one dominant gene, Ms2 , and one recessive mutant have been cloned in wheat (Ni et al, ; Tucker, Baumann, & Kouidri, ; Wang et al, ; Xia et al, ), with Ms2 mutants being widely used for wheat breeding and potentially for hybrid wheat breeding (Ni et al, ). Other genes involved in male sterility in wheat include the genes Ms26 and Ms45 which are involved in the formation of the pollen cell wall similar to ms1 which is a transcription factor and regulates the post‐meiotic development of the anther (Dong et al, ; Singh, Kumar, Thilges, Cho, & Cigan, ; Tucker et al, ; Wang et al, ). Here, we set out to identify other genes involved in pollen viability in wheat and show their possible use as genes involved in a genic male sterility system.…”