CSIRO Plant Industry, Queensland Bioscience Precinct, 306 Carmody Rd, St Lucia, Brisbane 4067, QLD, Australia.
BMC Plant Biol. 2014 Jul 26;14:190. doi: 10.1186/s12870-014-0190-x.
The understanding of sugarcane genetics has lagged behind that of other members of the Poaceae family such as wheat, rice, barley and sorghum mainly due to the complexity, size and polyploidization of the genome. We have used the genetic map of a sugarcane cultivar to generate a consensus genetic map to increase genome coverage for comparison to the sorghum genome. We have utilized the recently developed sugarcane DArT array to increase the marker density within the genetic map. The sequence of these DArT markers plus SNP and EST-SSR markers was then used to form a bridge to the sorghum genomic sequence by BLAST alignment to start to unravel the complex genomic architecture of sugarcane.
Comparative mapping revealed that certain sugarcane chromosomes show greater levels of synteny to sorghum than others. On a macrosyntenic level a good collinearity was observed between sugarcane and sorghum for 4 of the 8 homology groups (HGs). These 4 HGs were syntenic to four sorghum chromosomes with from 98% to 100% of these chromosomes covered by these linked markers. Four major chromosome rearrangements were identified between the other four sugarcane HGs and sorghum, two of which were condensations of chromosomes reducing the basic chromosome number of sugarcane from x = 10 to x = 8. This macro level of synteny was transferred to other members within the Poaceae family such as maize to uncover the important evolutionary relationships that exist between sugarcane and these species.
Comparative mapping of sugarcane to the sorghum genome has revealed new information on the genome structure of sugarcane which will help guide identification of important genes for use in sugarcane breeding. Furthermore of the four major chromosome rearrangements identified in this study, three were common to maize providing some evidence that chromosome reduction from a common paleo-ancestor of both maize and sugarcane was driven by the same translocation events seen in both species.
由于基因组的复杂性、大小和多倍性，甘蔗遗传学的理解落后于禾本科的其他成员，如小麦、水稻、大麦和高粱。我们利用甘蔗品种的遗传图谱生成了一个共识遗传图谱，以增加基因组覆盖范围，以便与高粱基因组进行比较。我们利用最近开发的甘蔗 DArT 数组来增加遗传图谱内的标记密度。然后，利用这些 DArT 标记加上 SNP 和 EST-SSR 标记的序列，通过 BLAST 比对形成与高粱基因组序列的桥梁，开始揭示甘蔗复杂的基因组结构。
比较作图显示，某些甘蔗染色体与高粱的同源性高于其他染色体。在宏观同源性水平上，甘蔗和高粱的 8 个同源群（HGs）中的 4 个同源群之间观察到很好的共线性。这 4 个 HG 与高粱的 4 个染色体同源，这些染色体的 98%到 100%被这些连锁标记覆盖。在其他 4 个甘蔗 HG 和高粱之间鉴定出了 4 个主要的染色体重排，其中 2 个是染色体的浓缩，使甘蔗的基本染色体数从 x = 10 减少到 x = 8。这种宏观水平的同源性被转移到禾本科的其他成员，如玉米，以揭示甘蔗和这些物种之间存在的重要进化关系。
甘蔗与高粱基因组的比较作图揭示了甘蔗基因组结构的新信息，这将有助于指导鉴定用于甘蔗育种的重要基因。此外，在本研究中鉴定的 4 个主要染色体重排中，有 3 个与玉米共有，这为玉米和甘蔗的共同祖先发生染色体减少提供了一些证据，而这种染色体减少是由两种物种中相同的易位事件驱动的。
