Construction of a male sterility system for hybrid rice breeding and seed production using a nuclear male sterility gene

Abstract

The breeding and large-scale adoption of hybrid seeds is an important achievement in agriculture. Rice hybrid seed production uses cytoplasmic male sterile lines or photoperiod/thermo-sensitive genic male sterile lines (PTGMS) as female parent. Cytoplasmic male sterile lines are propagated via cross-pollination by corresponding maintainer lines, whereas PTGMS lines are propagated via self-pollination under environmental conditions restoring male fertility. Despite huge successes, both systems have their intrinsic drawbacks. Here, we constructed a rice male sterility system using a nuclear gene named Oryza sativa No Pollen 1 (OsNP1). OsNP1 encodes a putative glucose–methanol–choline oxidoreductase regulating tapetum degeneration and pollen exine formation; it is specifically expressed in the tapetum and miscrospores. The osnp1 mutant plant displays normal vegetative growth but complete male sterility insensitive to environmental conditions. OsNP1 was coupled with an α-amylase gene to devitalize transgenic pollen and the red fluorescence protein (DsRed) gene to mark transgenic seed and transformed into the osnp1 mutant. Self-pollination of the transgenic plant carrying a single hemizygous transgene produced nontransgenic male sterile and transgenic fertile seeds in 1:1 ratio that can be sorted out based on the red fluorescence coded by DsRed. Cross-pollination of the fertile transgenic plants to the nontransgenic male sterile plants propagated the male sterile seeds of high purity. The male sterile line was crossed with ∼1,200 individual rice germplasms available. Approximately 85% of the F1s outperformed their parents in per plant yield, and 10% out-yielded the best local cultivars, indicating that the technology is promising in hybrid rice breeding and production.

Male sterility in soybean: Occurrence, molecular basis and utilization

“…Plant male reproduction phase involves a series of developmental stages from stamen primordial meristem to pollen granule formation and pollination, where deletion or abnormality of any gene will lead to MS (Budar & Pelletier, ; Chen & Liu, ). Significant achievements have been obtained on exploring genes, the analysis of molecular mechanism and its application associated with MS in major field crops, such as rice (Chang et al, ; Fan et al, ), wheat (Ni et al, ; Xia et al, ), maize (Zhang, Wu, et al, ) and other crops. In recent years, although some achievements have been made in soybean to explore the fertility genes, their molecular mechanisms, however, detailed research and application of MS still were under progress compared with improvements in related other crops such as wheat and rice.…”

“…In the view of the defects of these two types of MS, it is particularly important to study the genetic mechanism of MS and its key genes, explore the genetic basis of MS and transform or create a new MS line in soybean. Recently, Chang et al () constructed a rice MS system by using a nuclear gene OsNP1 . OsNP1 coupled with an α ‐amylase (pollen‐inactivated gene) to devitalize transgenic pollen and the red fluorescence protein ( DsRed , marker‐selecting gene) to mark transgenic seed and transformed into the osnp1 mutant, which obtains a maintainer of this mutant, and the rice NMS line can produce homozygous sterile line seeds for use in heterosis utilization (Chang et al, ).…”

“…Recently, Chang et al () constructed a rice MS system by using a nuclear gene OsNP1 . OsNP1 coupled with an α ‐amylase (pollen‐inactivated gene) to devitalize transgenic pollen and the red fluorescence protein ( DsRed , marker‐selecting gene) to mark transgenic seed and transformed into the osnp1 mutant, which obtains a maintainer of this mutant, and the rice NMS line can produce homozygous sterile line seeds for use in heterosis utilization (Chang et al, ). This technology is called “Smart sterile hybrid breeding technology”.…”

“…NMS used for seed production and hybrid breeding was limited due to the inability to propagate a pure MS line for commercial hybrid seed production. With the advancement of molecular gene cloning, plant transformation and recombinant DNA approaches, researchers and breeders can efficiently develop genetically engineered MS plants (Chang et al, ; Ni et al, ; Xia et al, ; Zhang, Wu, et al, ), which could facilitate the widespread use of the NMS system in commercial crop hybrid production. In summary, plant MS provides not only a key breeding basis for heterosis utilization in crop plants, but also an important material for studying the development of floral organs or stamens (male gametophyte) along with the regulation mechanism of sterile genes (Chen & Liu, ).…”

Registration of BTx623ms8, a New and Easily Identifiable Nuclear Male Sterile Mutant in Sorghum

“…In sorghum [ Sorghum bicolor (L.) Moench], CMS lines are exclusively used for developing sorghum hybrids (Jordan et al, 2011). Recently, it has been shown in rice ( Oryza sativa L.) that hybrids made with NMS lines have higher yield potential than hybrids made with traditional CMS lines (Chang et al, 2016; Zhou et al, 2014).…”