Gu Yu-Huan, Ko Wen-Hsiung
Dept. of Plant and Environmental Protection Services, Beaumont Agricultural Research Center, University of Hawaii at Manoa, Hilo, HI 96720, USA.
Can J Microbiol. 2005 Nov;51(11):934-40. doi: 10.1139/w05-073.
When protoplasts carrying metalaxyl-resistant (Mr) nuclei from the A1 isolate of Phytophthora parasitica were fused with protoplasts carrying chloroneb-resistant (Cnr) nuclei from the A2 isolate of the same species, fusion products carrying Mr nuclei were either the A2 or A1A2 type, while those carrying Cnr nuclei were the A1, A2, or A1A2 type. Fusion products carrying Mr and Cnr nuclei also behaved as the A1, A2, or A1A2 type. The result refutes the hypothesis that mating types in Phytophthora are controlled by nuclear genes. When nuclei from the A1 isolate of P. parasitica were fused with protoplasts from the A2 isolate of the same species and vice versa, all of the nuclear hybrids expressed the mating type characteristics of the protoplast parent. The same was true when the nuclei from the A1 isolate of P. parasitica were fused with the protoplasts from the A0 isolate of Phytophthora capsici and vice versa. These results confirm the observation that mating type genes are not located in the nuclei and suggest the presence of mating type genes in the cytoplasms of the recipient protoplasts. When mitochondria from the A1 isolate of P. parasitica were fused with protoplasts from the A2 isolate of the same species, the mating type of three out of five regenerated protoplasts was changed to the A1 type. The result demonstrated the decisive effect of mitochondrial donor sexuality on mating type characteristics of mitochondrial hybrids and suggested the presence of mating type genes in mitochondria. All of the mitochondrial hybrids resulting from the transfer of mitochondria from the A0 isolate of P. capsici into protoplasts from the A1 isolate of P. parasitica were all of the A0 type. The result supports the hypothesis of the presence of mating type genes in mitochondria in Phytophthora.
当携带来自寄生疫霉A1分离株的甲霜灵抗性（Mr）细胞核的原生质体与携带来自同一物种A2分离株的氯苯灵抗性（Cnr）细胞核的原生质体融合时，携带Mr细胞核的融合产物为A2型或A1A2型，而携带Cnr细胞核的融合产物为A1型、A2型或A1A2型。携带Mr和Cnr细胞核的融合产物也表现为A1型、A2型或A1A2型。该结果驳斥了疫霉交配型由核基因控制的假说。当寄生疫霉A1分离株的细胞核与同一物种A2分离株的原生质体融合，反之亦然时，所有核杂种均表现出原生质体亲本的交配型特征。当寄生疫霉A1分离株的细胞核与辣椒疫霉A0分离株的原生质体融合，反之亦然时，情况也是如此。这些结果证实了交配型基因不在细胞核中的观察结果，并表明受体原生质体的细胞质中存在交配型基因。当寄生疫霉A1分离株的线粒体与同一物种A2分离株的原生质体融合时，五个再生原生质体中有三个的交配型转变为A1型。该结果证明了线粒体供体性别对线粒体杂种交配型特征的决定性作用，并表明线粒体中存在交配型基因。由辣椒疫霉A0分离株的线粒体转移到寄生疫霉A1分离株的原生质体中产生的所有线粒体杂种均为A0型。该结果支持了疫霉线粒体中存在交配型基因的假说。
