Doust Andrew
University of Missouri-St. Louis, 1 University Boulevard, St Louis, MO 63121, USA.
Ann Bot. 2007 Nov;100(5):941-50. doi: 10.1093/aob/mcm040. Epub 2007 May 3.
The cereal crops domesticated from grasses provide a large percentage of the calories consumed by humans. Domestication and breeding in individual cereals has historically occurred in isolation, although this is rapidly changing with comparative genomics of the sequenced or soon-to-be sequenced genomes of rice, sorghum, maize and Brachypodium. Genetic information transferred through genomic comparisons is helping our understanding of genetically less tractable crops such as the hexaploid wheats and polyploid sugarcane, as well as the approx. 10 000 species of wild grasses. In turn, phylogenetic analysis helps put our knowledge of the morphology of cereal crops into an evolutionary context. GRASS ARCHITECTURE: Domestication often involves a change in the pattern and timing of branching, which affects both vegetative and inflorescence architecture, and ultimately yield. Cereal grasses exhibit two main forms of vegetative architecture: the pooid and erhartoid cereals such as wheat and rice have multiple basal tillers, while panicoid cereals such as maize, sorghum and the millets have few tillers or even only a single main stem. These differences are reflected in the differences between the wild species of pooid and some erhartoid grasses, which emphasize basal branching over axillary branching, and the panicoid grasses, where axillary branching is more frequently found. A combination of phylogenetic and genomic analysis is beginning to reveal the similarities and differences between different cereal crops, and relate these to the diversity of wild grasses to which they are related. Recent work on genes controlling branching emphasizes that developmental genetics needs to be viewed in both an evolutionary and ecological framework, if it is to be useful in understanding how morphology evolves. Increasingly, exploring the phylogenetic context of the crop grasses will suggest new ways to identify and create combinations of morphological traits that will best suit our future needs.
从禾本科植物驯化而来的谷类作物提供了人类消耗热量的很大一部分。历史上，各个谷类作物的驯化和育种都是孤立进行的，不过随着水稻、高粱、玉米和短柄草已测序或即将测序的基因组的比较基因组学研究，这种情况正在迅速改变。通过基因组比较传递的遗传信息有助于我们了解遗传上较难处理的作物，如六倍体小麦和多倍体甘蔗，以及大约10000种野生禾本科植物。反过来，系统发育分析有助于将我们对谷类作物形态学的认识置于进化背景之中。
驯化通常涉及分枝模式和时间的变化，这会影响营养结构和花序结构，最终影响产量。禾本科谷类作物表现出两种主要的营养结构形式：小麦和水稻等早熟禾类和类早熟禾类谷类作物有多个基部分蘖，而玉米、高粱和粟等黍类谷类作物分蘖很少，甚至只有一个主茎。这些差异反映在早熟禾类和一些类早熟禾类野生禾本科植物与黍类野生禾本科植物之间的差异上，前者强调基部分枝而非腋生分枝，而后者更常见腋生分枝。系统发育分析和基因组分析相结合，开始揭示不同谷类作物之间的异同，并将这些异同与它们所关联的野生禾本科植物的多样性联系起来。最近关于控制分枝的基因的研究强调，如果要有效地理解形态学是如何进化的，就需要在进化和生态框架中看待发育遗传学。越来越多的研究表明，探索谷类作物的系统发育背景将为识别和创造最适合我们未来需求的形态特征组合提供新方法。
