芝麻灌浆特性与灌浆期籽粒中内源激素含量变化研究

在大田栽培条件下,对芝麻品种‘郑芝98N09’的灌浆特性及灌浆期籽粒中内源激素含量变化进行了研究,为芝麻高产优质高效栽培及品质育种提供理论依据。结果表明:(1)第9～17节位芝麻籽粒干物质率最高;下部(8节以下)蒴果在灌浆24d时的蒴果鲜重达最大值(1.596g/蒴),27d时籽粒鲜重达最大值(0.318g/蒴),灌浆最快的时期为灌浆15～33d,干物质积累量达籽粒干重的61.75%;中部(9～20节)蒴果在灌浆27d时的蒴果鲜重达最大值(1.622g/蒴),籽粒鲜重也同期达最大值(0.379g/蒴),灌浆最快的时期为灌浆21～36d,干物质积累量达籽粒干重的74.21%;上部(20节以上)蒴果籽粒干物质积累最快的时期为灌浆9～12d和24～27d两个阶段。(2)中部蒴果GA3含量大于下部和上部蒴果,而ABA和IAA的含量则小于下部和上部蒴果;除GA3/ZR比值外,中部蒴果的ABA/GA3、ABA/ZR、GA3/IAA和ZR/IAA比值都小于下部和上部蒴果。(3)较高的ZR含量和较低的ABA/ZR、ABA/GA3、IAA/GA3和IAA/ZR比值利于胚乳细胞分裂、蒴果发育、籽粒库容建成及籽粒干物质充实。(4)单一激素含量与不同部位蒴果单蒴粒重均达显著或极显著负相关关系,内源激素相互间的关系对下部蒴果粒重增加影响较小,适当提高IAA/ZR、ABA/GA3、IAA/GA3比值,能显著提高中部和上部蒴果的单蒴籽粒干重。     

重穗型杂交水稻籽粒灌浆过程中强势和弱势颖花内源IAA、ABA和GA水平的动态状况

研究了重穗型杂交水稻培矮 6 4s/E3 2的灌浆过程和强、弱势颖花中内源IAA、ABA和GA1 GA3水平的动态状况。籽粒发育过程中不同内源激素水平高低依次为 :IAA >GA1 GA3>ABA。IAA和ABA水平在强势颖花中较高而GA1 GA3水平在弱势颖花中较高。 3种激素水平的变化与谷粒增重速率之间均存在正相关 ,两个最高的相关系数值分别存在于单位鲜重样本的IAA含量(ng/gFW ) 与籽粒鲜重的增重速率之间 (r =0 .82 1 8 )和单个籽粒IAA含量 (ng/grain)与籽粒干重的增重速率之间 (r =0 .8485 )。推测启动和维持籽粒灌浆过程可能需要较高的IAA水平 ;ABA可能具有促进籽粒中同化物的累积和种子成熟的作用 ;GA1 GA3可能具有保持弱势颖花活性的特殊作用     

重穗型杂交水稻籽粒灌浆过程中强势和强势颖花内源IAA、ABA和GA水平的动态状况

研究了重穗型杂交水稻培矮 6 4s/E3 2的灌浆过程和强、弱势颖花中内源IAA、ABA和GA1 GA3水平的动态状况。籽粒发育过程中不同内源激素水平高低依次为 :IAA >GA1 GA3>ABA。IAA和ABA水平在强势颖花中较高而GA1 GA3水平在弱势颖花中较高。 3种激素水平的变化与谷粒增重速率之间均存在正相关 ,两个最高的相关系数值分别存在于单位鲜重样本的IAA含量(ng/gFW ) 与籽粒鲜重的增重速率之间 (r =0 .82 1 8 )和单个籽粒IAA含量 (ng/grain)与籽粒干重的增重速率之间 (r =0 .8485 )。推测启动和维持籽粒灌浆过程可能需要较高的IAA水平 ;ABA可能具有促进籽粒中同化物的累积和种子成熟的作用 ;GA1 GA3可能具有保持弱势颖花活性的特殊作用     

杂交水稻及其亲本灌浆过程中内源激素含量的变化

杂交水稻笹优418在灌浆前期ABA含量高于笹锦和C418,后期低于其亲本;整个灌浆期间GA含量高于其亲本;笹优418和C418的IAA含量及其变化趋势都基本相同,前期含量升高,后期含量逐渐降低,笹锦在整个灌浆期间含量逐渐降低;笹优418和笹锦的ZR含量一直比较稳定,C418在灌浆前期含量较高,后期含量较低.     

GA3对杂交稻“粒间顶端优势”及灌浆期间籽粒内源IAA的影响

以杂交稻协优４１３为材料,他外源ＧＡ３对籽粒内源ＩＡＡ的影响。观察到开后其优势粒比劣势粒灌浆启动早,优势粒灌浆势下降后,劣势粒开始灌浆,且优势粒灌浆势值比劣势粒高,这种优劣势粒的灌浆异步现象是一种“粒间顶端优势”,即劣势粒的灌浆启动迟,与优势粒对劣热粒的抑制有关,籽粒灌浆期间优势粒内源ＩＡＡ含量增加早于劣势粒,优势粒内源ＩＡＡ峰值也高于劣势粒;优劣势粒灌浆势变化趋势与优劣势粒内源ＩＡＡ含量水平的变     

不同类型玉米籽粒灌浆过程中主要品质成分的变化规律（简报）

不同类型玉米籽粒发育过程中主要品质组分变化规律相同,只是数量不同。     

GA3对杂交稻“粒间顶端优势”及灌浆期间籽粒内源IAA的影响

以杂交稻协优 413为材料 ,研究了外源GA3 对籽粒内源IAA影响。观察到开花后其优势粒比劣势粒灌浆启动早 ,优势粒灌浆势下降后 ,劣势粒开始灌浆 ,且优势粒灌浆势峰值比劣势粒高 ,这种优劣势粒的灌浆异步现象是一种“粒间顶端优势” ,即劣势粒的灌浆启动迟 ,与优势粒对劣势粒的抑制有关。籽粒灌浆期间优势粒内源IAA含量增加早于劣势粒 ,优势粒内源IAA峰值也高于劣势粒 ;优劣势粒灌浆势变化趋势与优劣势粒内源IAA含量水平的变化趋势相似 ,“粒间顶端优势”似为内源IAA所调节。于初穗时喷施外源GA3,“放大”了单穗中优劣势粒灌浆异步效应 ,优势粒灌浆势更强 ,劣势粒更弱 ,即外源GA3 加强“粒间顶端优势”现象。在试验中还看到初穗期喷施 10～ 40mg/L浓度的GA3 溶液 ,随浓度提高 ,优势粒内源IAA含量增加 ,劣势粒IAA含量更低 ,这种变化似与施用GA3、使优势粒对IAA吸收更多有关     

大田遮阴对夏玉米籽粒形成过程中内源激素作用的影响

以振杰2号(ZJ2)、登海605(DH605)和郑单958(ZD958)为试验材料,大田条件下设置花粒期遮阴(S1)、穗期遮阴(S2)和全生育期遮阴(S3)3个处理,遮光度为60%,以自然光为对照(CK),研究大田遮阴对夏玉米籽粒形成过程中内源激素作用的影响.结果表明:遮阴条件下,雌穗原基分化的总小花数、花丝数、受精小花数均较CK不同程度地减少,败育籽粒数增多,不同处理的穗粒数表现为CKS2S1S3,S2、S1和S3的穗粒数较CK平均减少18.9%、43.7%和80.8%.遮阴后玉米籽粒的吲哚乙酸(IAA)、赤霉素(GA)和玉米素核苷(ZR)含量较CK略有降低,脱落酸(ABA)含量升高;且各处理的同一激素含量随籽粒发育的变化趋势一致.与正常籽粒相比,败育籽粒IAA含量的峰值由20 d前移至10 d,且积累少、下降快;GA和ZR含量均显著降低,而ABA含量在花后20 d内始终保持较高水平.因此,籽粒激素含量的变化可能是遮阴引起籽粒败育进而降低产量的重要原因之一.     

不同冠温特征冬小麦籽粒灌浆过程中内源激素含量的变化

"豫麦50"在灌浆后期冠层温度明显降低,表现为冷尾型;而"豫麦34"和"豫麦70"则在灌浆后期冠层温度有上升趋势,表现为暖尾型,在灌浆末期冷尾型与暖尾型小麦冠层温度相差超过2.5℃.冷尾型"豫麦50"强势粒中ZR、IAA、GA3含量峰值均高于其它两个品种,其ZR/ABA、GA3/ABA、IAA/ABA峰值亦高于暖尾型"豫麦70"和"豫麦34",ABA含量在灌浆中期上升快,高峰值大于"豫麦70"和"豫麦34",达到高峰后下降较快;"豫麦50"弱势粒中的各种激素含量仍较高.     

玉米籽粒灌浆特性对播期的响应

以‘京科528’(JK528)和‘郑单958’(ZD958)为试验材料,设置早春播(4月10日播种)和春播(5月14日播种)2个播期处理,研究不同播期条件下玉米的籽粒灌浆特性.结果表明: JK528、ZD958在早春播条件下的最终百粒重和产量显著高于春播,增幅分别为6.8%和10.1%、17.8%和9.2%;籽粒最大灌浆速率(G_max)、平均灌浆速率(G_ave)表现为早春播高于春播,而籽粒活跃灌浆期(P)呈相反趋势;JK528百粒重和产量显著高于ZD958,其中JK528百粒重和产量较ZD958高7.4 g和1189.6 kg·hm^-2,增幅分别为21.6%和10.8%;P表现为ZD958大于JK528,而W_max、G_max、G_ave和T_max表现为JK528大于ZD958;同一播期,JK528在灌浆中期的平均灌浆速率高于后期,且高于ZD958.相关分析表明,籽粒干物质积累量与平均气温和积温间呈极显著正相关.可见,充分利用光热资源,提高灌浆速率,有利于获得较高粒重,从而提高玉米产量.JK528在灌浆前中期灌浆速率快的优势弥补了其灌浆活跃期略短的情况,进而在不同播期条件下均可获得较高的粒重.     

烯效唑浸种对玉米幼苗生长和内源激素含量的影响

烯效唑浸种对玉米苗期叶片和叶鞘伸长生长有抑制作用,且抑制效应随烯效唑浓度的增大而增强,但植株粗壮,叶宽和茎基宽增加,根系增多,根长增加.烯效唑浸种的玉米幼苗中LAA和GA3含量下降,叶鞘中尤为明显;ZT含量则是地上部提高,根中下降,ABA含量提高,植株各器官中(IAA GA3)/ABA比值均下降,IAA/GA3比值均升高,IAA/ZT和GA3/ZT比值则是地上部降低,根中升高.     

不同基因型玉米间作的群体质量

采用大田试验,研究了不同基因型玉米间作的群体质量特征.结果表明,HF9‖XD20间作,植株中部叶片平均叶龄延长,而对下部和上部叶片影响不大;ZD958‖LD981间作,ZD958植株下部叶片平均叶龄延长,而中、上部叶片则缩短,LD981植株下、中、上部叶片平均叶龄均有所延长.吐丝前,群体叶面积指数(LAI)单间作无明显差异,吐丝后,HF9和LD981的LAI分别大于和显著大于单作群体,而ZD958和XD20则分别小于和显著小于单作群体.紧凑型品种和半紧凑型品种间作增加了群体透光率,吐丝后10d,4个品种棒三叶叶色值(SPADR)均有所增加,并且除ZD958外,其余3个品种棒三叶净光合速率均有所增加,其中LD981增加显著.间作对吐丝以前的群体干物质积累量影响不大,吐丝后,半紧凑型品种(HF9和LD981)的干物质积累量增加,其中LD981增加显著,而紧凑型品种(XD20和ZD958)的干物质积累量减少,其中ZD958显著减少;间作还提高了收获指数,并且两种间作群体的土地当量比(LER)均大于1.结果提示,紧凑型与半紧凑型玉米品种的间作可以提高群体质量,延长叶片功能期,提高光合效率,增加籽粒产量.     

玉米DEAD-box RNA解旋酶基因的克隆及分析

DEAD-box RNA解旋酶参与RNA转录、前体mRNA剪切、核糖体发生、核质运输、蛋白质翻译、RNA降解等重要的生命活动.根据本室在S-Mo17Rf3Rf3cDNA芯片研究中,检测到花粉发育后期RNA解旋酶上调表达的结果,应用RACE技术从S-Mo17Rf3Rf3花粉中克隆得到该RNA解旋酶基因全长cDNA,命名为ZmRH2并在GenBank注册登记 (DQ327709).序列分析表明：该cDNA全长1 652bp,从第163 bp开始到1 386bp含有一个开放阅读框,编码407个氨基酸.其编码的蛋白质具有DEAD-box RNA解旋酶特有的9个保守模体,与水稻、拟南芥和豌豆中的DEAD-box RNA解旋酶的氨基酸序列存在着很高的同源性.RT-PCR分析表明,该基因在近等基因系S-Mo17Rf3Rf3和S-Mo17rf3rf3的叶、根、和雌穗中的表达没有差异,但在花丝和花粉中有明显差异.     

Starch Mobilization in Ultradried Seed of Maize (Zea mays L.) During Germination

The effects of ultradry storage on the starch mobilization in maize (Zea mays L.) seed after aging were investigated. The results indicated that there were no significant differences in the content of ATP,starch, and soluble sugar, as well as the activity of amylase, between ultradried seeds and seeds stored at -20 ℃ during germination. These results were consistent with the higher level of vigor of the ultradried seed. Sieve tube introduction of a fluorescence dye (carboxyl fluoresceindiacetate) and laser confocal microscopy were used to study the development of plasmodesmata in the ultradried seeds. The results indicated that plasmodesmata developed well in ultradried seeds. Fluorescence analysis also showed that the fluorescence intensity in the radicle of ultradried seeds was stronger than that in seeds with a higher moisture content. This suggests that ultradry treatment has no adverse effects on the seeds. After seed imbibition, cell orgaelles could be resumed. It is concluded that ultradry seed storage is beneficial for maintaining seed vigor and that starchy mobilization proceeds regularly during germination.     

一个与玉米基因表达沉默有关的cDNA片段的克隆及序列分析

利用cDNA-AFLP技术分离了一个与玉米基因表达沉默有关的cDNA片段,Northern杂交分析表明,该基因在Mo17的苗期和雄穗生长锥伸长期都表达,但在Mo17与其亲缘关系较近的另一亲本杂交的F1代中却表现沉默,即表现单亲沉默。同源性分析表明,该克隆片段与GenBank中玉米通用调控因子(GRF)部分区段有98．6％的同源性,与玉米通用调控因子编码的mRNA部分序列有83％的同源性。以上结果表明,基因沉默可能是亲本GRF在F     

Characterization and Fine Mapping of a Necrotic Leaf Mutant in Maize (Zea mays L.)

Maize (Zea mays L.) is a commercially important crop. Its yield can be reduced by mutations in biosynthetic and degradative pathways that cause death. In this paper, we describe the necrotic leaf (nec-t) mutant, which was obtained from an inbred line, 81647. The nec-t mutant plants had yellow leaves with necrotic spots, reduced chlorophyll content, and the etiolated seedlings died under normal growth conditions. Transmission electron microscopy revealed scattered thylakoids, and reduced numbers of grana lamellae and chloroplasts per cell. Histochemical staining suggested that spot formation of nec-t leaves might be due to cell death. Genetic analysis showed that necrosis was caused by the mutation of a recessive locus. Using simple sequence repeat markers, the Nec-t gene was mapped between mmc0111 and bnlg2277 on the short arm of chromosome 2. A total of 1287 individuals with the mutant phenotype from a F₂ population were used for physical mapping. The Nec-t gene was located between markers T31 and H8 within a physical region of 131.7 kb.     

Plant Regeneration from Protoplasts of Corn(Zea mays L.)

Maize embryogenic calli induced from pollen were subcultured for one and one half years on N, basic medium supplemented with 2 mg/1 kinetin, 1 mg/l 6-benzyl-aminopurine, 0.3 mg/l 2,4-D, 500 mg/l casein hydrolysate and 250 mg/l glutamine. These embryogenic calli were used for protoplast isolation. Protoplasts were cultured on Z2 medium (Table 1) which is composed of rice protoplast culture basic medium 1 supplemented with 0.2 mg/l kinetin, 0.1 mg/l 6-benzyl-aminopurine, 0.5 mg/l 2,4-D, 200 mg/l casein hydrolysate, 100 mg/l glutamine and 2% coconut milk. The first division of regenerated cell occurred after 4-6 days in culture. After 3 weeks later, small calli could be seen with naked eyes. At this moment, addition of the same Z2 medium with decreased osmoticum twice for the protoplast culture is necessary. Regenerated calli, 2–4 mm in diameter, were transferred in succession on differentiation medium Z3 and Z4 for organogenesis. Embryogenesis and plant regeneration could occur simultaneously on Z4 differentiation medium. It seems that except the cultural conditions genotype and using of embryogenic materials are the two key factors for plant regeneration of maize protoplast and the former may be the critical one.     

Starch Mobilization in Ultradried Seed of Maize （Zea mays L.） During Germination

The effects of ultradry storage on the starch mobilization in maize (Zea mays L.) seed after aging were investigated. The results indicated that there were no significant differences in the content of ATP, starch, and soluble sugar, as well as the activity of amylase, between ultradried seeds and seeds stored at -20℃ during germination. These results were consistent with the higher level of vigor of the ultradried seed. Sieve tube introduction of a fluorescence dye (carboxyl fluoresceindiacetate) and laser confocal microscopy were used to study the development of plasmodesmata in the ultradried seeds. The results indicated that plasmodesmata developed well in ultradried seeds. Fluorescence analysis also showed that the fluorescence intensity in the radicle of ultradried seeds was stronger than that in seeds with a higher moisture content. This suggests that ultradry treatment has no adverse effects on the seeds. After seed imbibition, cell orgaelles could be resumed. It is concluded that ultradry seed storage is beneficial for maintaining seed vigor and that starchy mobilization proceeds regularly during germination.     

盐胁迫对玉米耐盐系与盐敏感系苗期几个生理生化指标的影响

对玉米耐盐系和盐敏感系在不同浓度盐胁迫下生理变化研究的结果表明,与盐敏感系相比,玉米耐盐系叶绿素含量高,脯氨酸、MDA含量及组织外渗液的相对电导率低,且变化幅度小。随盐浓度的增加,玉米耐盐系和盐敏感系的SOD、POD活性均先增加后降低,但玉米耐盐系峰值出现较晚。耐盐系的CAT活性明显大于盐敏感系;地上部分Na/K值小于盐敏感系,且增加的幅度小,而地下部分正相反。     

水杨酸对镉胁迫下玉米幼苗质膜透性和保护酶活性的影响

在Cd^2＋胁迫下,添加外源水杨酸（SA）的培养液中生长的玉米幼苗叶中超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性均提高,质膜透性降低,丙二醛（MDA）的积累减少,显示SA对Cd^2＋胁迫具有一定的缓解效应。