Molecular Cloning and Function Analysis of Two SQUAMOSA-Like MADS-Box Genes From Gossypium hirsutum L.

The MADS-box genes encode a large family of transcription factors having diverse roles in plant development. The SQUAMOSA （SQUA）/APETALA1 （AP1）/FRUITFULL （FUL） subfamily genes are essential regulators of floral transition and floral organ identity. Here we cloned two MADS-box genes, GhMADS22 and GhMADS23, belonging to the SQUA/AP1/FUL subgroup from Gossypium hirsutum L. Phylogenetic analysis and sequence alignment showed that GhMAD$22 and GhMADS23 belonged to the euFUL and euAP1 subclades, respectively. The two genes both had eight exons and seven introns from the start codon to the stop codon according to the alignment between the obtained cDNA sequence and the Gossypium raimondii L. genome sequence. Expression profile analysis showed that GhMADS22 and GhMADS23 were highly expressed in developing shoot apices, bracts, and sepals. Gibberellic acid promoted GhMADS22 and GhMADS23 expression in the shoot apex. Transgenic Arabidopsis lines overexpressing 35S：：GhMADS22 had abnormal flowers and bolted earlier than wild type under long-day conditions （16 h light/8 h dark）. Moreover, GhMADS22 over- expression delayed floral organ senescence and abscission and it could also respond to abscisic acid. In summary, GhMADS22 may have functions in promoting flowering, improving resistance and delaying senescence for cotton and thus it may be a candidate target for promoting early-maturation in cotton breeding.

Squamosa启动子结合蛋白基因家族在美国水稻微核心种质中的遗传结构分析

SQUAMOSA promoter-binding-like(SPL)基因家族作为一个植物特异转录因子家族,已被证实具有许多重要的生物学功能。本研究利用19条水稻SPL基因序列设计的引物,对引自美国农业部的171份水稻微核心种质的Oryza sativaL.SQUAMOSA promoter-binding-like(OsSPL)基因家族进行多态性分析。19对OsSPL基因引物扩增出140个条带,其中128个条带具有多态性,占91.4%;平均每个位点检测到7.4个条带。聚类与主坐标分析将171份材料划分为6类,类内品系呈相似地理生态分布,类与类之间无亚洲栽培稻与非洲栽培稻分化。性状关联分析表明,OsSPL基因家族的基因与每穗粒数、株高和抽穗期相关联。

Complex regulatory network of Betula BplSPL8 in planta

SQUAMOSA-promoter binding protein-like (SPL) proteins are plant-specific transcription factors and participate in different pathways, including the vegetative to reproductive transition, male sterility, biosynthesis of gibberellic acid (GA), plant morphogenesis and response to environmental stress. In this study, we generated transgenic Arabidopsis that overexpressed Betula BplSPL8 and confirmed that BplSPL8 is a transcription factor with transcriptional activation activity and is located in the nucleus. Functional analysis of BplSPL8 showed that it is involved in regulating different development processes: (1) BplSPL8 can delay flowering by reducing sensitivity to GA under short days; (2) BplSPL8 controls the number and morphogenesis of leaves, including up-rolling leaves under long days and folded leaves mediated by GA under short days; (3) BplSPL8 can promote root elongation during late development of roots and inhibit lateral root formation; (4) BplSPL8 may be involved in regulating carotenoid biosynthesis and secretion metabolism. These results show that there is a complex regulatory network for the SPL family genes that is mediated by other components and may provide a new insights for the functional research of SPL genes.

SPL转录因子调控植物花发育及其分子机制研究进展

SPL(squamosa promoter-binding protein-like)转录因子是植物所特有的一类基因家族,广泛存在于绿色植物中,在植物生长发育中具有重要作用。花发育是植物生殖发育中最为重要的一个过程,涉及不同发育方式的转变,即开花决定、花的发端和花器官发生与发育。简要综述了SPL基因的结构与功能并着重阐述了SPL基因在植物花发育过程中的分子机制及生物学功能。最后总结出:SPL转录因子可直接或间接通过参与光周期途径,赤霉素途径及年龄途径来调控植物的开花时间;SPL基因可通过直接激活下游花分生组织特异基因,如LEAFY(LFY),从而调控植物的成花转变;SPL基因可通过与下游花器官特征基因相互作用来调控花器官及其育性的发育,如调控花序、花柄的长度与外形及花器官的大小;SPL基因可调控植物大小孢子发生及雌雄配子体发育。据拟南芥的相关研究结果,初步构绘出拟南芥开花调控中的分子机制。

The miR156/SPL Module, a Regulatory Hub and Versatile Toolbox, Gears up Crops for Enhanced Agronomic Traits

In the past two decades, members of the SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE （SPL） family of transcription factors, first identified in Antirrhinum majus, have emerged as pivotal regulators of diverse biological processes in plants, including the timing of vegetative and reproductive phase change, leaf development, tillering/branching, plastochron, panicle/tassel architecture, fruit ripening, fertility, and response to stresses. Transcripts of a subset of SPLs are targeted for cleavage and/or translational repres- sion by microRNA156s （miR156s）. The levels of miR156s are regulated by both endogenous developmental cues and various external stimuli. Accumulating evidence shows that the regulatory circuit around the miR156/SPL module is highly conserved among phylogenetically distinct plant species, and plays impor- tant roles in regulating plant fitness, biomass, and yield. With the expanding knowledge and a mechanistic understanding of their roles and regulatory relationship, we can now harness the miR156/SPL module as a plethora of tools to genetically manipulate crops for optimal parameters in growth and development, and ultimately to maximize yield by intelligent design of crops.

Genome-wide analysis and molecular dissection of the SPL gene family in Salvia miltiorrhiza

SQUAMOSA promoter binding protein-likes （SPLs） are plant-specific transcription factors playing vital regulatory roles in plant growth and development. There is no information about SPLs in Salvia miltiorrhiza （Danshen）, a significant medicinal plant widely used in Traditional Chinese medicine （TCM） for＆gt;1,700 years and an emerging model plant for TCM studies. Through genome-wide identification and subsequent molecular cloning, we identified a total 15 SmSPLs with divergent sequence features, gene structures, and motifs. Comparative analysis showed sequence conservation between SmSPLs and their Arabidopsis counterparts. A phylogenetic tree clusters SmSPLs into six groups. Many of the motifs identified commonly exist in a group/subgroup, implying their functional redundancy. Eight SmSPLs were predicted and experimental y validated to be targets of miR156/157. SmSPLs were differen-tial y expressed in various tissues of S. milltiorrhiza. The expression of miR156/157-targeted SmSPLs was increased with＆amp;nbsp;the maturation of S. miltiorrhiza, whereas the expression of miR156/157 was decreased, confirming the regulatory roles of miR156/157 in SmSPLs and suggesting the functions of SmSPLs in S. miltiorrhiza development. The expression of miR156/157 was negatively correlated with miR172 during the maturation of S. miltiorrhiza. The results indicate the significance and complexity of SmSPL-, miR156-, and miR172-mediated regula-tion of developmental timing in S. miltiorrhiza.

十字花科开花相关基因SBP进化的基因组信息学分析

开花是植物由营养生长转为生殖生长的一个标志,鳞状启动子结合蛋白样(squamosa promoter binding protein-like, SBP)是一类重要调控开花相关的基因。在8个十字花科基因组中对SBP进行比较分析,鉴定了每个基因组中SBP的同源拷贝,每个基因组中基因拷贝数存在显著差异,其中最多的是在甘蓝中,有30个基因;一个突出的发现是在四倍体基因组中不同亚基因组的SBP具有一定的偏性,如四倍体芥菜-A基因组SBP拷贝数(21)高于芥菜-B基因组(19),在四倍体欧洲油菜中A基因组的SBP拷贝数(23)高于芥菜-A基因组(21),但低于欧洲油菜-C基因组中拷贝数(25)。搜索SBP处于共线性区域上基因,发现不同的全基因组加倍事件都有利于家族基因拷贝数扩增,尤其是十字花科共有的古老加倍(β),拟南芥、萝卜、黑芥等6个基因组的SBP基因几乎都与β加倍关联的重复区域相关联;另外串联重复加倍对于家族基因扩增也具有重要作用。对系统发育进行分析,并对同一事件的同义核苷酸置换率(Ks)进行比较,发现甘蓝、萝卜进化速率可能比白菜快;另外一个重要的发现是四倍体亚基因组A中SBP的进化速率快于另外的B和C基因组。本研究为认识十字花科开花相关转录因子SBP进化提供了重要的基因组学基础,有助于今后的更深入研究。