水稻成花素Hd3a及其受体分子机制研究进展

成花素是有一个控制开花位点的基因FT(FLOWERING LOCUS T)编码的产物,成花素FT是植物开花途径中的关键整合因子。而水稻中的Hd3a(HEADING DATE 3a)是拟南芥FT的同源基因,Hd3a蛋白即是水稻中的成花激素,其在叶片中表达并通过微管组织运输到顶端分生组织,同成花素受体14-3-3蛋白结合,然后又附着到另一种转录因子OsFD1(FLOWERING LOCUS D)上形成成花素激活复合体,使开花基因OsMADS15功能活跃起来。文中对水稻成花素Hd3a及其受体14-3-3蛋白分子作用机制的研究进展进行了综述,为进一步研究植物开花分子生物学提供参考。     

The mRNA of the Arabidopsis gene FT moves from leaf to shoot apex and induces flowering

Day length controls flowering time in many plants. The day-length signal is perceived in the leaf, but how this signal is transduced to the shoot apex, where floral initiation occurs, is not known. In Arabidopsis, the day-length response depends on the induction of the FLOWERING LOCUS T (FT) gene. We show here that local induction of FT in a single Arabidopsis leaf is sufficient to trigger flowering. The FT messenger RNA is transported to the shoot apex, where downstream genes are activated. These data suggest that the FT mRNA is an important component of the elusive "florigen" signal that moves from leaf to shoot apex.     

Cloning and Characterization of Putative Hd6 Ortholog Associated with Zea mays L.Photoperiod Sensitivity

The photoperiod response of fowering is critical to the survival and successful reproduction in crops.The Hd6 gene,encoding a protein similar to the Arabidopsis α-subunit of CASEIN KINASE2α(CK2α)has been reported to affect flowering time through the photoperiodic pathway in rice.In this study,the maize ortholog,ZmHd6,has been cloned and its role in the photoperiodic pathway was investigated.ZmHd6 encodes 332 amino acids with six distinct domains: two CK2 active domains,a nuclear localization signal sequence,a N terminal domain,an ATP binding site,and an active site of serine/threonine protein kinase.ZmHd6 was constitutively expressed in the leaves and shoot apical meristem(SAM)with the highest expression in SAMs of plants with seven leaves under long and short day conditions.Delayed flowering time under long day(LD)conditions were observed in ZmHd6 overexpression transgenic Arabidopsis plants compared to the wild type.In transgenic Arabidopsis plants,ZmHd6 was expressed in a circadian oscillatory pattern,TOC1 peak expression was delayed,new G1,CO,and FT expressions reached to peak after 3 h while entering illumination period and oscillatory expression patterns of CO and FT were created during the dark phase.These results suggested that ZmHd6 might negatively regulate flowering time under LD conditions by delaying TOC1 peak expression and disrupting CO and FT expression in transgenic Arabidopsis plants.     

成花素的移动性及其在育种中的应用

开花是植物从营养生长进入生殖生长的转折点。近年的研究表明,FT就是寻找多年的成花素。FT蛋白在叶片合成,通过韧皮部从芽接部位移动到接穗或根部,其过表达常导致植物提早开花,以上特点在促进木本植物提早开花、缩短童期、加速育种具有重要价值。综述FT蛋白的移动为成花必须,FT蛋白芽接移动性在一年生及多年生植物的差异、FT促进观赏植物提早开花、利用FT加速育种进程等方面的进展,为相关研究提供参考。     

The CCT domain-containing gene family has large impacts on heading date,regional adaptation,and grain yield in rice

There are 41 members of the CCT(CO, CO-like, and TOC1) domain-containing gene family in rice, which are divided into three subfamilies: COL(CONSTANS-like), CMF(CCT motif family), and PRR(pseudoresponse regulator). The first flowering gene to be isolated by map-based cloning, Heading date 1(Hd1), which is the orthologue of CO in rice, belongs to COL. The central regulator of plant development, Ghd7, belongs to CMF. The major role in controlling rice distribution to high latitudes, Ghd7.1/PRR37, belongs to PRR. Both of Hd1, Ghd7 and Ghd7.1 simultaneously control grain number, plant height, and the heading date. To date, 13 CCT family genes from these three subfamilies have been shown to regulate flowering. Some of them have pleiotropic effects on grain yield, plant height, and abiotic stresses, and others function as circadian oscillators. There are two independent photoperiod flowering pathways that are mediated by GI-Hd1-Hd3 a/RFT and GI-Ehd1-Hd3 a/RFT in rice. CCT family genes are involved in both pathways. The latest study reveals that protein interaction between Hd1 and Ghd7 integrates the two pathways. CCT family genes are rich in natural variation because rice cultivars have been subjected to natural and artificial selection for different day lengths in the process of domestication and improvement. Alleles of several crucial CCT family genes such as Hd1, Ghd7, and Ghd7.1 exhibit geographic distribution patterns and are highly associated with yield potentials. In addition, CCT family genes are probably involved in the responses to abiotic stress, which should be emphasized in future work. In general, CCT family genes play important roles in regulating flowering, plant growth, and grain yield. The functional identification and elucidation of the molecular mechanisms of CCT family genes would help construct a flowering regulatory network and maximize their contribution to rice production.     

花期干旱胁迫对籼稻近等基因系水分和光合生理的影响

【Objective】An indica near-isogenic rice lines were treated with drought stress at flowering stage to study water and photosynthetic physiology changes of flag leaf. By analyzing the relationships among agronomic phenotype characters, water and photosynthetic physiology changes and fertility of rice, the authors try to accumulate data for drought tolerance evaluation of rice.【Method】The rice materials were suffered with drought stress begin from heading of main shoot for 15 days, water and photosynthetic physiology parameters were measured after treatment.【Result】The results showed that the indica near-isogenic rice represented various drought tolerance, and there was no correlation between drought tolerance and agronomic phenotype characters, neither with physiological activities of rice under well watered condition. However, under drought stress at flowering stage, the correlation coefficient between drought resistance indexes and changes of water content of flag leaf, water potential of flag leaf, stomatal conductance of flag leaf were 0.614**, 0.514** and 0.541**, respectively. This indicates that rice drought tolerance has a correlation with changes of water content, water potential and stomatal conductance. In addition, except the correlation coefficient between drought resistance indexes and changes of Fv/Fm of flag leaf (0.470*), there was no correlation between rice drought tolerance and photosynthetic physiology.【Conclusion】In summery, the changes of water physiology parameters could be used as indicators for screening rice with drought tolerance.     

CO/FT调节元件与植物开花时间调节研究进展

综述了CO/FT调节元件与植物开花时间调节的最新研究进展。开花是植物由营养生长向生殖生长转变的关键过程。光周期和温度在植物开花时间控制中起主要作用。在拟南芥和水稻中,CONSTANS（CO）对植物的日照长度测定至关重要,它与其靶基因FLOWERING LOCUS T（FT）构成的调节元件（regulon）在依赖于光周期的开花过程中起重要作用。目前已从多种植物中鉴定出CO和FT基因,并对其在开花时间的调控作用进行了深入研究。     

水稻抽穗期基因酵母双杂交cDNA文库的构建及分析

为研究水稻开花调控的分子网络,构建了水稻品种中花11幼穗分化前倒二叶叶片的酵母双杂交cDNA文库。制备了高质量的总RNA,用Oligo(dT)引物反转录合成cDNA第一链和Long Distance PCR合成双链cD-NA,通过SMART同源重组交换技术在酵母菌株AH109中建立酵母双杂交所需的水稻倒二叶叶片cDNA文库。文库质量检测结果表明:cDNA文库的转化率为1.178×106/3μg pGADT7-Rec,文库滴度为2.65×108 cfu/mL,重组率为94.7%,插入片段长度为350～2 000bp。该文库可用来筛选水稻抽穗期基因的互作蛋白。     

转玉米PEPC基因水稻的农艺性状及生理特性

以稳定的转PEPC基因水稻和未转基因野生型水稻为供试材料,测定稻株开花期间地上部干物质的累积量及籽粒中可溶性糖、淀粉和蛋白质含量.结果表明:与未转基因野生型水稻相比,转PEPC基因水稻叶片、茎鞘和穗干重都有部分增加,但以穗增重为主;开花后14 d,与未转基因野生型水稻相比,转PEPC基因水稻籽粒中可溶性糖含量和蛋白质含量显著增加,但其淀粉含量没有增加,推测转PEPC基因水稻籽粒中较多的可溶性糖可能会更多地转化为蛋白质.     

光皮桦BlFTL基因的克隆和表达模式

通过反转录-聚合酶链式反应（RT?鄄PCR）结合如cDNA末端快速克隆（RACE）技术从光皮桦Betula luminifera中克隆到1个FT类似基因,命名为BlFTL。该基因cDNA全长为924 bp（GenBank登录号:JQ951966）,包含1个525 bp的开放阅读框（116~640 bp）,编码1个含174个氨基酸的蛋白,且具有FT蛋白典型的磷脂酰乙醇胺结合蛋白（PEBP）结构域。与已有部分植物中FT蛋白同源比对结果显示,BlFTL与无花果Ficus carica中FcFT序列相似性最高,达到了94%。4月为光皮桦开花期,雌花中BlFTL基因的表达量最高,茎和叶片中表达量很低。比较正常开花和不开花无性系植株嫩茎和叶片在不同时间BlFTL基因的表达情况,结果表明:BlFTL在不开花无性系植株中基本不表达,而正常开花植株中,BlFTL主要在雌花序和混合芽形成的8月以后表达。图8参13     

寒地水稻苗期耐碱研究及形态鉴定指标评价

为了探索碱胁迫对寒地水稻生长的影响,以15份水稻品种为研究对象,培养方式为液培,培养液为木村培养液。药剂处理使用Na2CO3+NaHCO3混合碱(质量配比1:3),溶液质量浓度为0.20%,分析了寒地水稻苗期耐碱性及形态鉴定指标。结果表明:0.20%混合碱胁迫后苗长和根系长度均有下降趋势,对根系的伸长生长抑制作用显著,但地上和地下部对碱胁迫敏感性不相关。碱胁迫延迟水稻的叶龄进程,降低叶面积、绿叶数、根系干质量、冠层干物质积累和根冠比,刺激水稻提前进入分蘖期。单株叶面积变化、绿叶数、根冠比和根冠长度比的相对值可作为水稻苗期耐碱性鉴定的形态指标。     

灌浆结实阶段水分逆境对超级稻叶片丙二醛含量的影响

通过水份仪结合称重法人为控制土壤水分的盆栽试验,研究灌浆结实阶段水分逆境对不同类型超级稻品种叶片丙二醛(MDA)含量的影响.结果表明:水稻灌浆结实阶段对水分的敏感性较强,开花至花后30 d不同时段的水分逆境均导致叶片丙二醛含量显著增加,尤其花后30 d时叶片丙二醛含量较对照增加更为明显.不同水分条件下各品种倒二叶的丙二醛含量也均显著高于剑叶,水分逆境导致水稻叶片尤其是倒二叶的丙二醛含量显著升高,叶片膜脂过氧化程度增强,加速了叶片的衰老进程.不同品种由于对水分逆境响应的敏感性差异而受影响的程度不同,相对于普通杂交稻汕优63来说,超级稻品种受到的影响要小.     

高等植物开花基因FT研究进展

FT是光周期途径植物开花时间决定关键基因,FT基因编码的蛋白产物是可以长距离转运的成花激素,在花形成过程中起关键作用。目前,已经证明FT基因的表达可促进植物提早开花。主要对植物开花基因FT研究进展及其在花发育转换过程中的功能等研究现状进行综述,并对该基因研究前景提出展望。     

吉林省稻穗瘟药剂防治指标的初步研究

文中确定了吉林省稻穗瘟病的经济损失允许水平:水稻黄熟期穗瘟发病率8～10％或穗瘟病情指数3～4。又根据吉林省有代表性的八个试验点五年的稻叶、穗瘟系统调查资料分析认为，决定吉林省生产中稻穗瘟最终病情的因素有三个:一是田间叶瘟基数;二是抽穗扬花期的气象条件;三是由当地生态栽培条件、水稻品种及稻瘟病菌生理小种群体共同决定的稻株抗病力。在此基础上提出吉林省稻穗瘟药剂防治指标。     

转基因水稻中GUS蛋白质的检测及其表达特征

【目的】建立转基因水稻中GUS蛋白质的免疫学检测方法,并了解花椰菜花叶病毒（CaMV）35S启动子驱动的GUS蛋白质在转基因水稻中的表达特征。【方法】以细菌基因组DNA为模板,PCR扩增GUS基因后克隆到表达载体pET30a中,测序验证的重组子转入大肠杆菌表达菌BL21中,IPTG诱导获得重组表达的GUS蛋白质,用HIS-tag beads纯化后作为免疫原免疫小鼠制备GUS蛋白质特异的抗体,通过免疫印迹分析筛选高特异性的单克隆抗体,用Broadford法对重组的GUS蛋白质进行定量,对不同浓度的GUS蛋白质进行免疫印迹分析,绘制检测GUS蛋白质的标准曲线,通过与标准曲线的比较对水稻叶片中GUS蛋白质进行定量分析。提取不同时期、不同部位的水稻总蛋白质,包括苗期的地上部、地下部,分蘖期的茎、茎节、叶鞘、叶枕、叶片上部、叶片中部和叶片下部,孕穗期的茎、穗轴、叶鞘、叶枕、叶片、幼穗（长度分别为1、2、10和20 cm）,开花期的茎、穗轴、叶鞘、叶片、穗子,成熟期的茎、叶片、授粉后不同时期的种子（分别为授粉后10、20、30和40 d）、乳熟期的胚、胚乳和颖壳、成熟种子的全种子、胚、胚乳和颖壳以及不同时期的叶片和根部材料等。SDS-PAGE分离后用抗体检测其GUS蛋白质的丰度。【结果】筛选获得了高特异性的抗GUS单克隆抗体（编号为#27）,用该抗体检测转基因水稻中及重组的GUS蛋白质均呈现特异条带,没有可见的背景信号,用本研究建立的免疫印迹方法对重组GUS蛋白质的检测下限约为4 ng,可检出转基因水稻单粒大米2.5%样品中（约0.6 mg）的GUS蛋白质。在不同时期的转基因水稻叶片中GUS蛋白质的表达丰度基本稳定,而在水稻根部的GUS丰度随生长急剧减少,5叶期根中的表达量不到3叶期的三分之一,到6叶期检测不到GUS蛋白质。在水稻苗期叶片中,GUS蛋白质约占鲜重的0.02‰。另外,除分蘖期以后的根部之外,GUS蛋白质几乎在所有的水稻组织部位中呈组成型表达,只是不同组织中的表达量略有差异,如在孕穗期和开花期的茎及颖壳中的表达量较低。【结论】建立了具有应用价值的对转基因水稻中GUS蛋白质丰度检测的免疫印记方法。该方法特异性高、样品用量少、不依赖于GUS蛋白质的酶活性、测定结果易于在不同实验室间比较。证明了35S启动子驱动的GUS蛋白质在转基因水稻中基本呈组成型表达。     

杂交水稻抽穗结实期间叶片衰老的生理生化研究

研究了大田杂交水稻汕优6号冠层上部三片功能叶衰老过程中一些生理生化变化。结果表明：叶片衰老时最早出现光合作用速率下降,其次是蛋白质降解,而后是叶绿素、RNA含量下降,最后原生质选透性丧失。在叶片衰老早期还明显看到一些新的过氧化物酶同工酶带的出现。在此期间植株和穗干重明显增加,而叶片和茎鞘干重明显减少。衰老期间各种生理生化参数变化,证实了杂交水稻冠层上部三片叶自下而上顺序衰老的现象,以及叶片与籽粒间物质的再调配。此外,对上述的各种参数作为衰老指标的适合性进行了讨论。