Molecular Marker-assisted Selection Of Bt Insecticidal Maintainer Line Of CMS Hybrid Rice

The present study aimed at transfering an elite transgenic locus from a Bt transgenic line Minhui63(referred as Minhui63/Bt)available in this lab into two indica three-line hybrid rice maintainer linesâ…¡-32B and Fuyi B using marker-assisted selection(MAS)technique.The main results and conclusions obtained are as follows:(1)A total of 114 and 100 SSLP markers were screened out from 400 SSRs,which were applied for background selection of Fuyi B andâ…¡-32B, respectively.The average density of these SSLP markers to each genome of these maintainer lines reached at 4.33 and 3.46 Mb per marker;(2)Foreground selection was conducted on each backcross generation. The detected Bt transgenic locus presented normal segregation ration as monogenic locus;The examined positive transgenic plants performed complete protection of plant against leaffolder.These results thus confirmed the foreign Bt gene in Minhui63/Bt was able to stably pass down during backcross and maintain its original insecticidal activity;(3)Background selection was continued to BC₄ generation.Two plants N75028-11 and N75028-10 that met our breeding purpose were eventually screened out from backcross population of 11-32B.To specify,all SSLP markers for the plant N75028-11 were recovered to recurrent parent type except for those on a segment of 11.50-14.95 Mb surrounding Bt.Similarly, all markers for the plant N75028-10 were also recovered except for those on two segments with range from 8.09 Mb to 12.35 Mb surrounding Bt and from 0.91 Mb to 4.42 Mb on the tip of chromosome 6.The MAS scheme of Fuyi B was still on the phase of BC₃F₂with overall genetic background recovery rate at 94.67%.