Functional Analysis Of MxⅡ Gene Of Mitochondria In Rice

Honglian cytoplasmic male sterility (HL-CMS) is one of three major CMS types used in commercial production of hybrid rice (Oryza sativa L.). Previous study showed that the sterility caused by HL-CMS candidate gene orf216 may be in relation to the interaction between ORF216 protein and the proeins coded by mxI and mxII.In this study, the effects of overexpression of mxI and mxII in HL-CMS line YTA and BT-CMS line Shuangjiu A on their fertilities were explored, The main results were as follows.1. By using TRIzol method, the total RNA from maintainer lines YTB was extracted and mxII gene was amplified from cDNA obtained by reverse transcription. CaMV35S∷Rf1b5'∷mxII expression vector was constructed by recombination between mxII and pCAMBIA1305.1, and then transformed into YTA, by Agrobacterium-mediated transformation method. there were 64 positive transgenic plants from 263 transgenic plants obtained. By I-KI staining, some fertile pollen of positive transgenic plants were detected. Among them, T1 seeds from 12 positive transgenic plants were harvested. It is suggested that overexpression of mxII in HL-CMS line YTA could cause its partial fertility restoration.2. Using the constructed mxI overexpession vector CaMV35S∷Rf1b5'∷mxI (Huwen, 2010) transformed BT-CMS line shuangjiu A and some positive transgenic plants were obtained. Pollen staining with I-KI showed that the fertilties of some T0 plants were partly restored, suggesting that mxI overexpression could partially restore the fertility of BT-CMS line Shuangjiu A.