Embrapa Maize and Sorghum, Sete Lagoas, Minas Gerais, Brazil.
PLoS One. 2011;6(6):e20830. doi: 10.1371/journal.pone.0020830. Epub 2011 Jun 14.
Acid soils comprise up to 50% of the world's arable lands and in these areas aluminum (Al) toxicity impairs root growth, strongly limiting crop yield. Food security is thereby compromised in many developing countries located in tropical and subtropical regions worldwide. In sorghum, SbMATE, an Al-activated citrate transporter, underlies the Alt(SB) locus on chromosome 3 and confers Al tolerance via Al-activated root citrate release.
Population structure was studied in 254 sorghum accessions representative of the diversity present in cultivated sorghums. Al tolerance was assessed as the degree of root growth inhibition in nutrient solution containing Al. A genetic analysis based on markers flanking Alt(SB) and SbMATE expression was undertaken to assess a possible role for Alt(SB) in Al tolerant accessions. In addition, the mode of gene action was estimated concerning the Al tolerance trait. Comparisons between models that include population structure were applied to assess the importance of each subpopulation to Al tolerance.
CONCLUSION/SIGNIFICANCE: Six subpopulations were revealed featuring specific racial and geographic origins. Al tolerance was found to be rather rare and present primarily in guinea and to lesser extent in caudatum subpopulations. Alt(SB) was found to play a role in Al tolerance in most of the Al tolerant accessions. A striking variation was observed in the mode of gene action for the Al tolerance trait, which ranged from almost complete recessivity to near complete dominance, with a higher frequency of partially recessive sources of Al tolerance. A possible interpretation of our results concerning the origin and evolution of Al tolerance in cultivated sorghum is discussed. This study demonstrates the importance of deeply exploring the crop diversity reservoir both for a comprehensive view of the dynamics underlying the distribution and function of Al tolerance genes and to design efficient molecular breeding strategies aimed at enhancing Al tolerance.
酸性土壤占世界可耕地的 50%，在这些地区，铝（Al）毒性会损害根系生长，严重限制作物产量。因此，在全球热带和亚热带地区的许多发展中国家，粮食安全受到了威胁。在高粱中，SbMATE 是一种 Al 激活的柠檬酸转运蛋白，位于第 3 号染色体上的 Alt(SB) 基因座下，通过 Al 激活根释放柠檬酸来赋予 Al 耐受性。
对 254 份高粱品种进行了群体结构研究，这些品种代表了栽培高粱的多样性。在含有 Al 的营养液中评估根生长抑制程度来评估 Al 耐受性。基于侧翼 Alt(SB)和 SbMATE 表达的标记进行了遗传分析，以评估 Alt(SB)在 Al 耐受品种中的可能作用。此外，还估算了基因作用方式与 Al 耐受性性状的关系。对包括群体结构的模型进行了比较，以评估每个亚群体对 Al 耐受性的重要性。
结论/意义：揭示了 6 个亚群体，具有特定的种族和地理起源。发现 Al 耐受性相当罕见，主要存在于几内亚，其次是 caudatum 亚群体。发现 Alt(SB)在大多数 Al 耐受品种中对 Al 耐受性起作用。Al 耐受性性状的基因作用方式存在显著差异，从几乎完全隐性到近乎完全显性，具有较高频率的部分隐性 Al 耐受性来源。我们对栽培高粱中 Al 耐受性的起源和进化的研究结果进行了讨论。本研究表明，深入探索作物多样性库对于全面了解 Al 耐受性基因的分布和功能的动态以及设计旨在提高 Al 耐受性的有效分子育种策略非常重要。
