Six-rowed barley originated from a mutation in a homeodomain-leucine zipper I-class homeobox gene
Six-rowed barley originated from a mutation in a homeodomain-leucine zipper I-class homeobox gene
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DOI：
10.1073/pnas.0608580104
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发表时间：
2007-01-23
影响因子：
11.1
通讯作者：
Yano, Masahiro
中科院分区：
文献类型：
--
作者：
Komatsuda, Takao;Pourkheirandish, Mohammad;Yano, Masahiro
在谷类作物的驯化过程中，增加种子产量一直是一个共同的目标，大麦（Hordeum，vulgare ssp. vulgare）选择了具有六棱穗的表型，其稳定地产生通常谷粒数的三倍。这种产量的提高使大麦成为近东新石器时代文明的奠基作物。大麦穗状花序在每个轴节上有一个中央小穗和两个侧生小穗。野生型祖细胞（H. vulgare ssp. spontaneum）具有二棱表型，具有额外的、严格不发育的侧行;这种自然适应有利于破碎后的种子传播，直到最近，六棱表型的起源仍然未知。本研究利用定位克隆的方法，分离了大麦六棱穗的基因vrs 1（six-rowed spike 1）。野生型Vrs 1等位基因（二棱大麦）编码一个转录因子，包括一个同源结构域与紧密相连的亮氨酸拉链基序。VRS 1的表达严格定位于未成熟穗的侧小穗原基中，表明VRS 1蛋白抑制侧行的发育。Vrs 1功能的丧失导致二棱大麦发育不良的侧小穗完全转化为六棱大麦发育完全的可育小穗。系统发育分析表明，六棱表型重复起源，在不同的时间和不同的地区，通过独立的Vrs 1突变。
Increased seed production has been a common goal during the domestication of cereal crops, and early cultivators of barley (Hordeum, vulgare ssp. vulgare) selected a phenotype with a six-rowed spike that stably produced three times the usual grain number. This improved yield established barley as a founder crop for the Near Eastern Neolithic civilization. The barley spike has one central and two lateral spikelets at each rachis node. The wild-type progenitor (H. vulgare ssp. spontaneum) has a two-rowed phenotype, with additional, strictly rudimentary, lateral rows; this natural adaptation is advantageous for seed dispersal after shattering, Until recently, the origin of the six-rowed phenotype remained unknown. In the present study, we isolated vrs1 (six-rowed spike 1), the gene responsible for the six-rowed spike in barley, by means of positional cloning. The wild-type Vrs1 allele (for two-rowed barley) encodes a transcription factor that includes a homeodomain with a closely linked leucine zipper motif. Expression of Vrs1 was strictly localized in the lateral-spikelet primordia of immature spikes, suggesting that the VRS1 protein suppresses development of the lateral rows. Loss of function of Vrs1 resulted in complete conversion of the rudimentary lateral spikelets in two-rowed barley into fully developed fertile spikelets in the six-rowed phenotype. Phylogenetic analysis demonstrated that the six-rowed phenotype originated repeatedly, at different times and in different regions, through independent mutations of Vrs1.