我们确定了CRISPR-Cas9基因编辑系统在烟草(Nicotianabenthamiana)等位基因中诱导的突变的特异性以及随后的遗传稳定性。为此,我们使用农杆菌递送的针对α-1,3-岩藻糖基转移酶1(FucT1)和β-1,2-木糖基转移酶1(XylT1)基因的CRISPR-Cas9系统制备了248株突变植物,突变率分别为22.5%和25%,分别,两个基因座均为20.5%。在T0中NbFucT1基因座处具有野生型(WT)等位基因的个体在下一代中进一步分离为嵌合后代(37-54%),而在T1世代中,纯合T0突变体倾向于比其他双等位基因和嵌合子代产生更多(〜70%)的纯合子。T0代中约有81.8%和77.4%的纯合和双等位基因突变,分别,在下一代稳定遗传,并且大约50%的无Cas9突变体在T2代中分离。发现一个纯合突变体(Ta161-1)在NbFucT1中插入1bp,在NbXylT1中缺失4bp,可产生具有相同等位基因的T2后代,指示无论插入或缺失类型如何,整合的Cas9都没有活性。我们的结果提供了有关烟草转化体中CRISPR靶向基因座等位基因遗传的经验证据,并指出了导致进一步诱变的潜在因素。
We determined the specificity of mutations induced by the CRISPR-Cas9 gene-editing system in tobacco (Nicotiana benthamiana) alleles and subsequent genetic stability. For this, we prepared 248 mutant plants using an Agrobacterium-delivered CRISPR-Cas9 system targeting α-1,3-fucosyltransferase 1 (FucT1) and β-1,2-xylosyltransferase1 (XylT1) genes, for which the mutation rates were 22.5% and 25%, respectively, with 20.5% for both loci. Individuals with wild-type (WT) alleles at the NbFucT1 locus in T0 were further segregated into chimeric progeny (37-54%) in the next generation, whereas homozygous T0 mutants tended to produce more (~70%) homozygotes than other bi-allelic and chimeric progenies in the T1 generation. Approximately 81.8% and 77.4% of the homozygous and bi-allelic mutations in T0 generation, respectively, were stably inherited in the next generation, and approximately 50% of the Cas9-free mutants were segregated in T2 generation. One homozygous mutant (Ta 161-1) with a +1 bp insertion in NbFucT1 and a -4 bp deletion in NbXylT1 was found to produce T2 progenies with the same alleles, indicating no activity of the integrated Cas9 irrespective of the insertion or deletion type. Our results provide empirical evidence regarding the genetic inheritance of alleles at CRISPR-targeted loci in tobacco transformants and indicate the potential factors contributing to further mutagenesis.