Six-rowed spike4 (Vrs4) controls spikelet determinacy and row-type in barley
Six-rowed spike4 (Vrs4) controls spikelet determinacy and row-type in barley
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DOI：
10.1073/pnas.1221950110
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发表时间：
2013-08-06
影响因子：
11.1
通讯作者：
Schnurbusch, Thorsten
中科院分区：
文献类型：
--
作者：
Koppolu, Ravi;Anwar, Nadia;Schnurbusch, Thorsten
大麦（Hordeum vulgare L.）的花序结构在小麦科植物中是常见的，在每条轴节间有一到三个单花小穗。三穗分生组织是大麦穗的独特特征之一，在每条轴节间产生三个小穗（一个中心小穗和两个侧边小穗）。三穗分生组织侧穗的育性使大麦穗具有行型同一性。与不育侧穗的二排穗相比，六排穗具有可育的侧穗，单穗产量更高。到目前为止，在大麦中分离到两个控制行型表型的位点，包括六排穗1 （Vrs1）和medium- c。本研究分离了玉米（Zea mays L.）花序结构基因RAMOSA2 （RA2）的大麦同源基因六棱穗4 （Vrs4）。大麦RA2 （HvRA2）的18个编码突变与侧小穗育性和小穗确定性的丧失特异性相关。通过mRNA原位杂交和基因芯片的表达分析表明，Vrs4 （HvRA2）通过Vrs1 （HvHox1）控制行型途径，Vrs1 （HvHox1）是大麦侧小穗育性的负调控因子。此外，Vrs4还可能调控大麦RAMOSA3姊妹酶（HvSRA）的转录本，HvSRA是一种被认为参与海藻糖-6-磷酸稳态的海藻糖-6-磷酸磷酸酶，参与控制小穗的确定性。我们的表达数据表明，尽管RA2在不同的牧草物种中是保守的，但它的下游靶基因似乎在大麦和其他Triticeae部落物种中被修饰。
Inflorescence architecture of barley (Hordeum vulgare L.) is common among the Triticeae species, which bear one to three single-flowered spikelets at each rachis internode. Triple spikelet meristem is one of the unique features of barley spikes, in which three spikelets (one central and two lateral spikelets) are produced at each rachis internode. Fertility of the lateral spikelets at triple spikelet meristem gives row-type identity to barley spikes. Six-rowed spikes show fertile lateral spikelets and produce increased grain yield per spike, compared with two-rowed spikes with sterile lateral spikelets. Thus, far, two loci governing the row-type phenotype were isolated in barley that include Six-rowed spike1 (Vrs1) and Intermedium-C. In the present study, we isolated Six-rowed spike4 (Vrs4), a barley ortholog of the maize (Zea mays L.) inflorescence architecture gene RAMOSA2 (RA2). Eighteen coding mutations in barley RA2 (HvRA2) were specifically associated with lateral spikelet fertility and loss of spikelet determinacy. Expression analyses through mRNA in situ hybridization and microarray showed that Vrs4 (HvRA2) controls the row-type pathway through Vrs1 (HvHox1), a negative regulator of lateral spikelet fertility in barley. Moreover, Vrs4 may also regulate transcripts of barley SISTER OF RAMOSA3 (HvSRA), a putative trehalose-6-phosphate phosphatase involved in trehalose-6-phosphate homeostasis implicated to control spikelet determinacy. Our expression data illustrated that, although RA2 is conserved among different grass species, its down-stream target genes appear to be modified in barley and possibly other species of tribe Triticeae.