过量表达URO基因抑制拟南芥次生细胞壁开关基因表达

植物次生细胞壁的发育受到一系列转录调控因子的调节.但关于这一过程如何与植物整体发育相整合,一直少有报道.拟南芥URO(UP-RIGHT ROSETTE)基因过量表达导致在相应突变体uro中自由态生长素浓度明显升高,并导致该突变体中次生细胞壁发育减弱.本研究利用突变体uro及其杂合子uro/+,通过定量PCR的方法,检测了一系列调控植物次生细胞壁分化相关基因的表达情况.结果表明,在uro/uro和uro/+中,植物次生细胞壁发育开关基因的表达受到明显抑制,而对于木质部导管细胞分化的开关基因没有明显影响.因此,URO基因是介导植物细胞壁次生加厚与植物生长发育状态关联的基因,URO基因通过抑制次生细胞壁发育达到维持细胞的生长状态的效果.

白桦SAUR基因家族鉴定及生物信息学分析

SAUR基因家族作为植物生长素早期响应基因家族中最大的一个家族,参与到植物细胞伸长、果实发育、胁迫应答等多个生物学过程。本研究基于白桦全基因组数据,对白桦SAUR基因家族进行鉴定和生物信息学分析。结果表明,白桦共有61个SAUR家族基因,这些基因不均匀分布在14条染色体上,理化性质分析表明,大部分BpSAUR蛋白呈碱性,为不稳定蛋白,脂溶性系数较高,为亲水性;系统进化和基因结构分析表明,61个白桦SAUR基因被分为4类(Group Ⅰ~Group Ⅳ),其中Group Ⅳ中BpSAUR基因最多,同一分类的BpSAUR基因更倾向于在染色体上聚集分布,大部分白桦SAUR家族基因为无内含子或少内含子基因。白桦SAUR家族基因启动子还拥有多个光响应、激素响应元件与逆境胁迫作用元件,说明其可能参与白桦生长发育及胁迫应答等多个生物学过程。该家族基因在白桦的不同组织部位和不同发育阶段的表达量也不同,主要在幼茎、成熟茎和成熟叶中集中表达。本研究通过对白桦SAUR基因家族进行深入分析,以期为白桦分子育种奠定良好基础。

Ca^(2+)-dependent TaCCD1 cooperates with TaSAUR215 to enhance plasma membrane H^(+)-ATPase activity and alkali stress tolerance by inhibiting PP2C-mediated dephosphorylation of TaHA2 in wheat

Alkali stress is a major constraint for crop production in many regions of saline-alkali land.However,little is known about the mechanisms through which wheat responds to alkali stress.In this study,we identified a calcium ion-binding protein from wheat,TaCCD1,which is critical for regulating the plasma membrane(PM)H^(+)-ATPase-mediated alkali stress response.PM H+-ATPase activity is closely related to alkali tolerance in the wheat variety Shanrong 4(SR4).We found that two D-clade type 2C protein phosphatases,TaPP2C.D1 and TaPP2C.D8(TaPP2C.D1/8),negatively modulate alkali stress tolerance by dephosphorylating the penultimate threonine residue(Thr926)of TaHA2 and thereby inhibiting PM H+-ATPase activity.Alkali stress induces the expression of TaCCD1 in SR4,and TaCCD1 interacts with TaSAUR215,an early auxin-responsive protein.These responses are both dependent on calcium signaling triggered by alkali stress.TaCCD1 enhances the inhibitory effect of TaSAUR215 on TaPP2C.D1/8 activity,thereby promoting the activity of the PM H^(+)-ATPase TaHA2 and alkali stress tolerance in wheat.Functional and genetic analyses verified the effects of these genes in response to alkali stress,indicating that TaPP2C.D1/8 function downstream of TaSAUR215 and TaCCD1.Collectively,this study uncovers a new signaling pathway that regulates wheat responses to alkali stress,in which Ca^(2+)-dependent TaCCD1 cooperates with TaSAUR215 to enhance PM H+-ATPase activity and alkali stress tolerance by inhibiting TaPP2C.D1/8-mediated dephosphorylation of PM H+-ATPase TaHA2 in wheat.

Small auxin upregulated RNA (SAUR) gene family in maize: Identification, evolution, and its phylogenetic comparison with Arabidopsis, rice, and sorghum

Small auxin-up RNAs （.SAURs） are the early auxin- responsive genes represented by a large multigene family in plants. Here, we identified 79 SAUR gene family members from maize （Zea mays subsp, mays） by a reiterative database search and manual annotation. Phylogenetic analysis indicated that the SAUR proteins from Arabidopsis, rice, sorghum, and maize had divided into 16 groups. These genes were non-randomly distributed across the maize chromosomes, and segmental duplication and tandem duplication contributed to the expansion of the maize .SAUR gene family. Synteny analysis established ortholos^J relationships and functional linkages between SAUR genes in maize and sorghum genomes. We also found that the auxin-responsive elements were conserved in the upstream sequences of maize SAUR members. Selection analyses identified some significant site-specific constraints acted on most SAUR paralogs. Expression profiles based on microarray data have provided insights into the possible functional divergence among members of the .SAUR gene family. Quantitative real-time PCR analysis indicated that some of the 10 randomly selected ZmSAUR genes could be induced at least in maize shoot or root tissue tested. The results reveal a comprehensive overview of the maize .SAUR gene family and may pave the way for deciphering their function during pJant development.

柑橘属SAUR基因家族的全基因组鉴定及表达分析

分析SAUR(Small auxin up-regulated RNA)基因家族在不同柑橘基因组中的数量、连锁群分布、基因结构、系统进化、基因表达模式等,从香橼、柚、莽山野橘和克里曼丁橘等基因组中分别鉴定到69、62、58和70个SAUR基因。SAUR在基因组上分布不均,呈现明显的串联重复现象,基因家族成员的差异可能是由于串联重复和染色体大片段复制引起。大多数柑橘SAUR基因不含内含子,含有SAUR特有的4个保守motif。系统进化树分析显示,来源于拟南芥、水稻、番茄、马铃薯和柑橘的629个SAUR基因分为9组,每一组都含有5个物种的家族成员,并且同一个物种的SAUR基因具有较近的遗传距离。顺式元件分析表明,CclSAUR基因家族成员的上游序列含有光响应、转录因子结合、激素响应、伤害响应、低温响应、玉米素代谢和类黄酮生物合成相关的元件。q RT-PCR分析结果显示,大多数CclSAUR都能响应外源IAA和低温处理。

杉木ClSAUR25基因5'侧翼序列的克隆与生物信息学分析

SAUR(Small auxin-up RNA)基因作为生长素信号早期响应基因,在调控植物生长发育以及对逆境胁迫的应答中扮演着关键角色。本研究通过染色体步移法从杉木基因组DNA中获得了ClSAUR25基因5'侧翼序列,并对其进行了生物信息学分析。结果表明,克隆获得ClSAUR25基因上游5'侧翼序列1471 bp,该序列具有3个核心启动子区和5个CpG岛。同时,该序列除了含有丰富的核心元件CAAT-box和TATA-box外,还含有乙烯和金属响应元件以及多个光响应、分生组织特异性、厌氧应答、胚乳表达等相关的顺式调控元件。本研究结果表明ClSAUR25基因启动子可能属于光诱导型启动子,同时暗示其在杉木应答非生物胁迫和生长发育调控中扮演着重要角色。