Identification and functional analysis of the MOC1 interacting protein 1

Rice tillering is one of the most important agronomic traits that determine grain yields.Our previous study has demonstrated that the MONOCULM1 (MOC1) gene is a key component that controls the formation of rice tiller buds.To further elucidate the molecular mechanism of MOC1 involved in the regulation of rice tillering,we performed a yeast-two-hybrid screening to identify MOC1 interacting proteins (MIPs).Here we reported that MIP1 interacted with MOC1 both in vitro and in vivo.The overexpression of MIP1 res...     

Tillering and panicle branching genes in rice

Rice (Oryza sativa L.) is one of the most important staple food crops in the world, and rice tillering and panicle branching are important traits determining grain yield. Since the gene MONOCULM 1 (MOC 1) was first characterized as a key regulator in controlling rice tillering and branching, great progress has been achieved in identifying important genes associated with grain yield, elucidating the genetic basis of yield-related traits. Some of these important genes were shown to be applicable for molecular breeding of high-yielding rice. This review focuses on recent advances, with emphasis on rice tillering and panicle branching genes, and their regulatory networks.     

甘蔗MOC1基因(ScMOC1)的克隆与表达分析

MONOCULM 1(MOC1)基因在植物腋分生组织和腋芽的形成中发挥重要作用,是植物分蘖关键调控基因。本研究利用同源基因克隆法结合RT-PCR、RACE技术从甘蔗品种ROC22中克隆获得MOC1的同源基因,命名为Sc MOC1。生物信息学分析发现该基因的c DNA序列包含一个长度为1299 bp的开放阅读框,编码432个氨基酸残基组成的含有GRAS保守结构域的非分泌蛋白,其分子量为45.43 k D,理化等电点p I为6.98。序列比对分析显示Sc MOC1与高粱(Sorghum bicolor(L.)Moench)、赖草(Leymus secalinus(Georgi)Tzvel.)、水稻(Oryza sativa L.)等禾本科植物同源蛋白氨基酸序列一致性较高;系统进化树分析显示其与高粱、小米草(Setaria italica(L.)P.Beauv.)、玉米(Zea mays L.)等禾本科植物MOC1同源蛋白亲缘关系最近;Sc MOC1在甘蔗品种ROC22中的序列变异分析发现,30个克隆得到的序列中共有46个SNP位点和29处In Del位点,其中1个位点发生的单个碱基缺失和另一个位点的4个碱基插入是造成基因编码蛋白序列变化的主要原因。中性检测表明,Sc MOC1在ROC22中遵循中性进化模型。采用实时荧光定量PCR分析Sc MOC1在甘蔗品种ROC22分蘖期不同组织部位(根、茎、叶、分蘖芽、叶鞘、生长点)、茎尖生长点和不同发育阶段腋芽(幼嫩腋芽、半大腋芽、较大腋芽、成熟休眠腋芽)的表达特征,结果显示Sc MOC1在分蘖期的ROC22中的表达具有组织特异性,在生命活跃的茎尖生长点处表达量最高;在腋芽形成发育过程中该基因表达总体呈现出"升-降-升-降"的趋势,说明Sc MOC1基因可能在甘蔗腋芽形成发育阶段中发挥作用。以上研究可推测Sc MOC1在甘蔗的分蘖性状调控上扮演重要的角色。本研究为Sc MOC1的功能研究及其在甘蔗产量分子辅助育种中的利用奠定基础。     

水稻多分蘖矮秆突变体htd1-2的遗传分析和基因定位

文章所采用的多分蘖矮秆突变体为htd1-2(high-tillering dwarf 1-2), 是野生型籼稻品种9311经350Gy的60Co- g射线辐射处理后产生的后代中选育出来的稳定多分蘖矮秆突变体。遗传分析表明, 突变体htd1-2多分蘖矮秆性状是由一对隐性核基因的突变造成的。文章利用简单重复序列(Simple sequence repeat, SSR)、酶切扩增多态性序列(Cleaved amplified polymorphic sequence, CAPS)和衍生型CAPS(derived CAPS, dCAPS)等分子标记的方法, 最终将多分蘖矮秆基因HIGH-TILLERING DWARF1-2(HTD1-2)定位在水稻第4号染色体116 kb的物理区间内。在该物理区间内有一个已经克隆的控制水稻分蘖的基因HIGH-TILLERING DWARF1(HTD1), 经过测序比对和dCAPS特异性分析, 认为HTD1就是HTD1-2基因。尽管突变体htd1与突变体htd1-2是等位基因的不同位点发生突变, 但是由于遗传背景的不同, 两者表型并不完全相同。此外, 通过去除分蘖芽的实验证明了突变体htd1-2的矮化部分是由于分蘖过多造成的。     

OsTIR1 and OsAFB2 downregulation via OsmiR393 overexpression leads to more tillers, early flowering and less tolerance to salt and drought in rice

The microRNA miR393 has been shown to play a role in plant development and in the stress response by targeting mRNAs that code for the auxin receptors in Arabidopsis. In this study, we verified that two rice auxin receptor gene homologs (OsTIR1 and OsAFB2) could be targeted by OsmiR393 (Os for Oryza sativa). Two new phenotypes (increased tillers and early flowering) and two previously observed phenotypes (reduced tolerance to salt and drought and hyposensitivity to auxin) were observed in the OsmiR393-overexpressing rice plants. The OsmiR393-overexpressing rice demonstrated hyposensitivity to synthetic auxin-analog treatments. These data indicated that the phenotypes of OsmiR393-overexpressing rice may be caused through hyposensitivity to the auxin signal by reduced expression of two auxin receptor genes (OsTIR1 and OsAFB2). The expression of an auxin transporter (OsAUX1) and a tillering inhibitor (OsTB1) were downregulated by overexpression of OsmiR393, which suggested that a gene chain from OsmiR393 to rice tillering may be from OsTIR1 and OsAFB2 to OsAUX1, which affected the transportation of auxin, then to OsTB1, which finally controlled tillering. The positive phenotypes (increased tillers and early flowering) and negative phenotypes (reduced tolerance to salt and hyposensitivity to auxin) of OsmiR393-overexpressing rice present a dilemma for molecular breeding.     

Natural variation in Tiller Number 1 affects its interaction with TIF1 to regulate tillering in rice

Tiller number per plant—a cardinal component of ideal plant architecture—affects grain yield potential. Thus, alleles positively affecting tillering must be mined to promote genetic improvement. Here, we report a Tiller Number 1 (TN1) protein harbouring a bromo-adjacent homology domain and RNA recognition motifs, identified through genome-wide association study of tiller numbers. Natural variation in TN1 affects its interaction with TIF1 (TN1 interaction factor 1) to affect DWARF14 expression and negatively regulate tiller number in rice. Further analysis of variations in TN1 among indica genotypes according to geographical distribution revealed that low-tillering varieties with TN1-hap^L are concentrated in Southeast Asia and East Asia, whereas high-tillering varieties with TN1-hap^H are concentrated in South Asia. Taken together, these results indicate that TN1 is a tillering regulatory factor whose alleles present apparent preferential utilization across geographical regions. Our findings advance the molecular understanding of tiller development.     

水稻非生物胁迫响应基因OsMIP1的表达与进化分析

MID1编码R-R型的MYB转录因子,对不同的非生物胁迫均有响应,特别是在水稻(Oryza sativa)生殖期会受到干旱胁迫的诱导,进而在一定程度上可以保持花粉的育性并稳定水稻产量。为进一步研究水稻MID1对非生物胁迫的响应网络,利用酵母双杂交系统筛选出与其互作的蛋白因子OsMIP1,并利用双分子荧光互补系统在本氏烟草(Nicotiana benthamiana)细胞中得到验证。结果表明,OsMIP1编码1个预测含有ENTH/ANTH/VHS结构域的跨膜转运蛋白。OsMIP1在根、茎、叶、小穗和胚乳中均有表达。干旱胁迫下,OsMIP1在叶片和生殖器官中表达,特别是在减数分裂后的小花中表达显著上调。这些结果暗示,OsMIP1在花器官抵抗干旱胁迫中起一定的作用。在水稻营养生长阶段,OsMIP1表达还受到包括Na Cl和甘露醇在内的其它非生物胁迫的影响,暗示其可能在其它非生物胁迫调节中也具有一定的作用。植物中关于编码ENTH/ANTH/VHS结构域蛋白的研究很少。通过对MIP1亚家族进化关系进行分析,结果表明,在被子植物中,MIP1可分为6大类,这6大类分别来自被子植物祖先中原本就存在的6个拷贝,在被子植物的进化过程中又经历了多次基因重复和拷贝丢失等事件。MIP1家族成员广泛分布于被子植物中并可能具有抗胁迫等功能。     

The Plant Architecture of Rice (<Emphasis Type="Italic">Oryza sativa</Emphasis>)

Plant architecture, a collection of the important agronomic traits that determine grain production in rice, is mainly affected by factors including tillering, plant height and panicle morphology. Recently, significant progress has been made in isolating and collecting of mutants that are defective in rice plant architecture. Although our understanding of the molecular mechanisms that control rice tillering, panicle development and plant height are still limited, new findings have begun to emerge. This review, therefore, summarizes the recent progress in exploring the mechanisms that control rice plant architecture.     

Heteroses in Net Photosynthetic Rate, Leaf Area, Tillering, and Some Physiological Characters of 35 F1 Rice Hybrids

Net photosynthetic rate, leaf area, tillering, shoot weight,and leaf area ratio for 35 F₁ rice (Oryza sativa L.) hybridsduring the vegetative stage were compared with correspondingvalues for parental varieties. Shoot weight and leaf area showedheterosis. However, hybrid vigour was not reflected in net photosyntheticrate. Leaf area was closely correlated with heteroses in shootdry weight and tillering. Thus F₁ rice hybrids grow vigorouslybecause of their high leaf area development, which is causedby high tillering. Key words: F₁ rice hybrid, Net photosynthetic rate, Leaf area     

Recent Progress on Rice Genetics in China

Through thousands of years of evolution and cultivation, tremendously rich genetic diversity has been accumulated in rice （Oryza sativa L.）, developing a large germplasm pool from which people can select varieties with morphologies of Interest and other important agronomic traits. With the development of modern genetics, scientists have paid more attention to the genetic value of these elite varieties and germplasms, and such rich rice resources provide a good foundation for genetic research in China. Approximately 100 000 accessions of radiation-, chemical- or insertion-induced mutagenesis have been generated since the 1980s, and great progress has been made on rice molecular genetics. So far at least 16 variant/mutant genes Including MOC1, BC1, SKC1, and Rfgenes have been isolated and characterized in China. These achievements greatly promote the research on functional genomics, understanding the mechanism of plant development and molecular design breeding of rice in China. Here we review the progress of three aspects of rice genetics in China： moving forward at the molecular level, genetic research on elite varieties and germplasms, and new gene screening and genetic analysis using mutants. The prospects of rice genetics are also discussed.     

水稻ES1参与生物钟基因表达调控以及逆境胁迫响应

生物钟参与调控植物所有的生长阶段和发育活动。维持植物生物钟稳定的基因在这一过程中起着决定性作用。在克隆了ES1 (EARLY SENESCENCE 1)基因并证明该基因影响水稻(Oryza sativa)叶片失水的基础上, 以前期分离得到的水稻突变体es1-1作为研究对象, 对es1-1及其野生型(日本晴)苗期的地上部分和地下部分进行基因芯片分析。结果表明, es1-1主要的上调基因有42个, 下调基因有14个, 这些差异基因涉及24种代谢途径, 包括调节水稻生物钟的途径(4个)、甲烷代谢途径(3个)和苯基丙氨酸代谢途径(3个)等。进一步对水稻生物钟相关基因进行表达图谱分析, 结果表明, 与野生型相比, es1-1中生物钟相关基因出现了不同程度的差异表达。对es1-1和野生型进行冷胁迫处理, 结果表明es1-1表现更加耐冷, 且冷处理后生物钟基因在日本晴(NPB)和es1-1中都表现出不同程度的差异表达。此外, 在分蘖盛期接种白叶枯菌, 发现es1-1对特定的白叶枯菌具有一定的抗性。由此推测ES1基因参与调控水稻生物钟基因的表达以及响应水稻部分逆境胁迫, 这为更深入研究水稻生物钟基因提供了新线索。     

Genetic interaction between 2 tillering genes, reduced culm number 1 (rcn1) and tillering dwarf gene d3, in rice

Mutant genes, reduced culm number 1 (rcn1) and bunketsuwaito tillering dwarf (d3), affect tiller number in rice (Oryza sativa L.) in opposite directions. The d3 mutant was reported to increase tiller number and reduce plant stature. Our objective was to compare the phenotype of the d3rcn1 double mutant with each single mutant and parental rice cultivar "Shiokari" and to clarify whether the Rcn1 gene interacted with the D3 gene. We recovered a new rcn1 mutant from Shiokari and developed d3rcn1 double mutant with Shiokari genetic background. A new rcn1 mutant, designated as "S-97-61" exhibited a reduction in tiller number and plant stature to about the same level as the previously reported original rcn1 mutant. Three near-isogenic lines, rcn1 mutant, d3 mutant, and d3rcn1 double mutant, were grown together with the parental Shiokari. The reduction in tillering by the rcn1 mutation was independent of the d3 genotype, and tillering number of d3rcn1 double mutant was between those of the d3 and rcn1 mutants. These results demonstrated that the Rcn1 gene was not involved in the D3-associated pathway in tillering control.     

Engineering OsBAK1 gene as a molecular tool to improve rice architecture for high yield

Generating a new variety of plant with erect-leaf is a critical strategy to improve rice grain yield, as plants with this trait can be dense-planted. The erect-leaf is a significant morphological trait partially regulated by Brassinosteroids (BRs) in rice plants. So far, only a few genes can be used for molecular breeding in rice. Here, we identified OsBAK1 as a potential gene to alter rice architecture. Based on rice genome sequences, four closely related homologs of Arabidopsis BAK1 ( AtBAK1 ) gene were amplified. Phylogenetic analysis and suppression of a weak Arabidopsis mutant bri1-5 indicated that OsBAK1 (Os08g0174700) is the closest relative of AtBAK1. Genetic, physiological, and biochemical analyses all suggest that the function of OsBAK1 is conserved with AtBAK1 . Overexpression of a truncated intracellular domain of OsBAK1 , but not the extracellular domain of OsBAK1 , resulted in a dwarfed phenotype, similar to the rice BR-insensitive mutant plants. The expression of OsBAK1 changed important agricultural traits of rice such as plant height, leaf erectness, grain morphologic features, and disease resistance responses. Our results suggested that a new rice variety with erect-leaf and normal reproduction can be generated simply by suppressing the expression level of OsBAK1 . Therefore, OsBAK1 is a potential molecular breeding tool for improving rice grain yield by modifying rice architecture.     

水稻OsMY1和OsRacD基因互作的分子鉴定

OsRacD是光敏核不育水稻农垦58S光周期育性转换信号通路中的重要分子开关,通过酵母双杂交筛选,从水稻幼穗中分离到一种与OsRacD 互作的新的肌球蛋白重链编码基因的cDNA片段,命名为OsMY1。本文在酵母双杂交体系鉴定的基础上,构建了OsMY1和OsRacD的原核表达载体,表达和纯化了融合蛋白GST-OsMY1 和His6-OsRacD, 通过pull down实验进一步确认了上述互作关系。本研究提示OsMY1和OsRacD可能在功能上相关,为深入研究二者在水稻生理功能上的联系提供了重要线索和依据。