Vol.:(0123456789) 1 3 Plant Mol Biol DOI 10.1007/s11103-017-0678-5 Evolvement of transgenic male-sterility and fertility-restoration system in rice for production of hybrid varieties Gundra Sivakrishna Rao 1  · Priyanka Deveshwar 2  · Malini Sharma 2  · Sanjay Kapoor 2  · Khareedu Venkateswara Rao 1   Received: 22 May 2017 / Accepted: 24 October 2017 © Springer Science+Business Media B.V. 2017 been successfully engineered in rice. For male fertility res- toration, transgenic rice plants carrying BnCysP1Si silenc- ing system were developed. The pollination of BnCysP1 male-sterile (female-fertile) plants with BnCysP1Si pollen resulted in normal grain flling. The F 1 seeds of BnCysP1 × BnCysP1Si when germinated on the MS basal medium con- taining PPT (5 mg/l) and hygromycin (70 mg/l) exhibited 1:1 (tolerant:sensitive) ratio and the tolerant plants invariably showed normal grain flling. The overall results clearly sug- gest that the customized male-sterility & fertility-restoration system can be exploited for quality hybrid seed production in various crops. Keywords Brassica napus · Cysteine protease · Hybrid seed production · Fertility-restoration · Male-sterility · Transgenic rice Introduction Rice (Oryza sativa, L.) is an important cereal crop which feeds more than half of the world’s population. Designing and development of high yielding rice varieties through con- ventional and molecular breeding methods are warranted as the demand for rice is increasing with the ever-increasing global population. Hybrid varieties can produce 20–50% higher yields than the inbred lines and more than half of the production of major crops, such as maize, sorghum, rape- seed and sunfower, comes from hybrid varieties (Li et al. 2007; Tester and Langridge 2010). Hybrid seed production involves an inbred male parent that pollinates a genetically distinct male-sterile female inbred parent. A number of male sterility systems have been employed/developed to prevent self-fertilization in the female parent, namely emasculation, chemical-induced male-sterility, cytoplasmic and nuclear Abstract Key message We have developed a unique male-steril- ity and fertility-restoration system in rice by combining Brassica napus cysteine-protease gene (BnCysP1) with anther-specifc P12 promoter of rice for facilitating pro- duction of hybrid varieties. Abstract In diverse crop plants, male-sterility has been exploited as a useful approach for production of hybrid vari- eties to harness the benefts of hybrid vigour. The promoter region of Os12bglu38 gene of rice has been isolated from the developing panicles and was designated as P12. The pro- moter was fused with gusA reporter gene and was expressed in Arabidopsis and rice systems. Transgenic plants exhibited GUS activity in tapetal cells and pollen of the developing anthers indicating anther/pollen-specifc expression of the promoter. For engineering nuclear male sterility, the cod- ing region of Brassica napus cysteine protease1 (BnCysP1) was isolated from developing seeds and fused to P12 pro- moter. Transgenic rice plants obtained with P12-BnCysP1 failed to produce functional pollen grains. The F 1 seeds obtained from BnCysP1 male-sterile plants and untrans- formed controls showed 1:1 (tolerant:sensitive) ratio when germinated on the MS medium supplemented with phos- phinothricin (5 mg/l), confrming that the male sterility has Electronic supplementary material The online version of this article (doi:10.1007/s11103-017-0678-5) contains supplementary material, which is available to authorized users. * Khareedu Venkateswara Rao rao_kv1@redifmail.com 1 Centre for Plant Molecular Biology, Osmania University, Hyderabad, T.S. 500007, India 2 Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India