玉米pepc基因在杂交转育的转基因水稻后代中的传递和表达特征

在合肥、海南两地以高光效转玉米pepc基因水稻为父本，与培矮64S、2302S、2304S、2306S、5129、02428、皖粳97和双九A等8个受体杂交，转育转pepc基因水稻新种质材料。至2002年已转育成一批转pepc基因水稻品系，对这些材料世代跟踪研究显示：(1)玉米pepc基因以一个显性基因稳定传递给后代，符合孟德尔分离规律，自交F2呈3：1分离，BC1为1：1分离；(2)玉米pepc基因在杂交转育的转基因水稻中高水平表达，与受体亲本相比，PEPC活性提高3.7～17．4倍，表达水平与受体亲本和转基因拷贝数有关，来源相同的世代间有相似的表达水平，但同一世代不同个体间表达水平有差异，这可能与其位置效应、拷贝数和环境条件有关；(3)杂交后代结实率不高，容易产生异交结实导致转基因材料混杂分离。采取抗生素催芽初筛、PCR分析抽检、PEPC活性测定和田间表型观测的转玉米pepc基因水稻选育筛选体系，辅之以受体为轮回亲本适当回交可有效地控制。利用该途径已育成3个稳定的高表达的转玉米pepc基因水稻品系H1596、H1597和Y1470，说明通过常规杂交转育的方法，可以培育实用的稳定高表达的转玉米pepc基因水稻品种。

Inheritance and Expression of the Maize pepc Gene in Progenies of Transgenic Rice Bred by Crossing

By cross breeding,the maize pepc gene in the pepc transgenic rice was successfully incorporated into the parents of two-,three-line hybrid rice,including sterile lines (Peiai64S,2302S,2304S,2306S and Shuangjiu A) and restorer lines (5129,02428 and Wanjing97) to breed the high-photosynthetic efficiency parents of hybrid rice and utilize heterosis between C_4 and C_4/C_3 rice.Some lines of pepc transgenic rice (LPTR) have been developed.The study on the generations of LPTR suggests the following:(1)The segregation observed in F_2 and BC_1 progenies demonstrated that pepc transgene inherited as a single dominant gene in the progenies of LPTR.(2)The maize pepc gene is actively expressed at high level in LPTR,and changes of pepc gene expression in the progenies of LPTR may be related to position effect,difference of gene copy number and environmental factors.(3)Through the selection method of soaking seeds into hygromycin solution to germinate,tracing the pepc gene by PCR analysis,evaluating the performance of the rice plants in the field and examining PEPC activities,the segregation of the pepc transgene in LPTR was controlled effectively.Based on the above strategy three pepc transgene lines,H1596,H1597 and Y1470,have been selected.The result suggests that it is possible to breed practical,stable and high-expression pepc transgenic rice by conventional crossing.