Yin T-M, DiFazio S P, Gunter L E, Jawdy S S, Boerjan W, Tuskan G A
Environmental Sciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37830-6422, USA.
Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, Technologiepark 927, B-9000 Gent, Belgium.
New Phytol. 2004 Oct;164(1):95-105. doi: 10.1111/j.1469-8137.2004.01161.x.
• In an attempt to elucidate the molecular mechanisms of Melampsora rust resistance in Populus trichocarpa, we have mapped two resistance loci, MXC3 and MER, and intensively characterized the flanking genomic sequence for the MXC3 locus and the level of linkage disequilibrium (LD) in natural populations. • We used an interspecific backcross pedigree and a genetic map that was highly saturated with AFLP and SSR markers, and assembled shotgun-sequence data in the region containing markers linked to MXC3. • The two loci were mapped to different linkage groups. Linkage disequilibrium for MXC3 was confined to two closely linked regions spanning 34 and 16 kb, respectively. The MXC3 region also contained six disease-resistance candidate genes. • The MER and MXC3 loci are clearly distinct, and may have different mechanisms of resistance, as different classes of putative resistance genes were present near each locus. The suppressed recombination previously observed in the MXC3 region was possibly caused by extensive hemizygous rearrangements confined to the original parent tree. The relatively low observed LD may facilitate association studies using candidate genes for rust resistance, but will probably inhibit marker-aided selection.
为了阐明毛果杨对美澳型核果锈菌抗性的分子机制，我们定位了两个抗性位点MXC3和MER，并深入研究了MXC3位点侧翼基因组序列以及自然群体中的连锁不平衡（LD）水平。我们使用了一个种间回交家系和一张高度饱和了AFLP和SSR标记的遗传图谱，并在包含与MXC3连锁标记的区域组装了鸟枪法测序数据。这两个位点被定位到不同的连锁群上。MXC3的连锁不平衡分别局限于两个紧密连锁的区域，跨度分别为34 kb和16 kb。MXC3区域还包含六个抗病候选基因。MER和MXC3位点明显不同，可能具有不同的抗性机制，因为每个位点附近存在不同类别的推定抗性基因。先前在MXC3区域观察到的重组抑制可能是由局限于原始亲本树的广泛半合体重排引起的。观察到的相对较低的LD可能有助于利用锈病抗性候选基因进行关联研究，但可能会抑制标记辅助选择。
