小麦杂种及其亲本苗期叶片家族基因差异表达及其与杂种优势关系的初步研究

为探讨小麦杂种优势形成的分子机理,以一套双列杂交组合的苗期叶片为材料,利用mRNA差异显示技术分析了杂种及其亲本间MADS－box、G－ box、Ser/Thr蛋白激酶、EIF－4A、ARF1基因家族共5类家族基因在杂交种和亲本之间的表达差异。并与杂种性状表现和杂种优势进行了相关分析。结果发现,除ARF1家族基因外,其余家族基因在杂种和亲本间存在显著的表达差异,差异表达类型可概括为4种：（1）双亲共沉默;（20单亲表达沉默;（3）杂种特异表达;（4）单亲表达一致。分析发现,MADS－box、G－box和EIF－4A家族基因在杂种和亲本间的差异表达模式相似,均以单亲特异表达和种特异表达类型所占比例最高。相关分析结果表明,以上所有家族基因的总体差异表达程度与所有性状的杂种表现均不相关,MADS－box家族基因中杂种特异表达类型与小穗数、单株产量和单穗产量杂种优势呈显著正相关,双亲共沉默类型与小穗数、千粒重和单穗产量杂种优势呈显著负相关,另外,EIF－4A家族基因中单亲表达一致型与单穗产量杂种优势呈显著正相,但双亲共沉默类型与小穗数和单穗产量杂种优势呈显著负相关,对于G－box基因家族而言,仅小穗数杂种优势和双亲共沉默类型成显著负相关,而蛋白激酶家族基因的各种差异类型与性状杂种优势的相关分析均不显著。这些研究表明,调控基因的差异表达与杂种优势形成有密切关系。     

玉米杂种与亲本穗分化期功能叶基因差异表达与杂种优势

为探讨玉米杂种优势的分子机理,以10个玉米自交系及其组配的38个杂交种为材料,利用cDNA-AFLP技术,分析杂种与亲本在玉米雌穗小穗分化期功能叶片的基因差异表达类型与主要农艺性状的杂种表现及杂种优势的关系。研究表明：（1）杂种的基因相对于其双亲,存在质和量的表达差异,其中质的差异表达类型包括：单亲沉默表达,双亲沉默表达,亲本显性表达和杂种特异表达等类型。（2）在雌穗小穗分化期,同一差异表达类型中不同杂交组合间差异很大;从总体平均看,杂种特异表达类型占25.22%,亲本显性表达类型占21.46%,双亲沉默表达类型占8.27%,单亲沉默表达类型占33.49%。（3）单亲沉默表达与株高的杂种表现呈显著正相关;双亲沉默表达与穗粗的杂种优势呈显著负相关,显性表达与行粒数和单株粒重的杂种优势呈显著负相关,其余表达类型与所有农艺性状杂种表现及杂种优势均不相关,并对结果进行了讨论。     

小麦杂交种与亲本发育早期种子的基因表达差异及其与杂种优势关系的初步研究

为深入探讨小麦杂种优势形成的分子机理,选取3个冬小麦品种(系)为一组亲本,3个为另一组亲本,配制了正反交18个杂交组合,以授粉后6d的杂交和自交种子为材料,应用mRNA差异显示技术(DDRT—PCR)研究了小麦杂交当代种子与其亲本自交种子基因的表达差异,并与杂种优势进行相关分析。为降低DDRT—PCR技术假阳性的不利影响,对每个引物组合均作了两次PCR扩增,在处理数据时,仅统计能重复出现的条带。结果发现：杂交种和亲本之间的基因表达模式有8类共15种：(1)单亲沉默型(2种),(2)单亲一致型(2种),(3)正交或反交沉默型(2种),(4)正交或反交特异型(2种),(5)正交或反交单亲一致型(4种),(6)杂交种特异型(1种),(7)双亲共沉默型(1种),(8)表达一致型(1种)。分析发现,小麦杂交种和亲本间存在显著的表达差异。在差异表达类型中,杂交种特异型和双亲共沉默型比例最低。对上述15种表达模式与杂种优势进行相关分析,结果表明,表达一致型与各产量性状杂种优势之间的相关均不显著,说明杂种优势是由某些有表达差异的基因造成。9个产量性状均能检测到一种以上与其显著或极显著相关的基因表达模式,有些性状受正负相关效应的共同影响;沉默型(包括单亲沉默型、正交或反交沉默型和双亲共沉默型)和正交或反交单亲一致型在杂种优势形成中发挥重要作用。这些研究表明,在种子发育早期,基因的差异表达与杂种优势形成之间可能存在较为复杂的关系。     

送春与多花兰种间杂交后代的ISSR分析

该文使用简单重复序列间( ISSR)分子标记,对送春与多花兰种间杂交后代进行了研究。结果表明：从80个ISSR引物中筛选出14个扩增效果稳定的ISSR引物,对两亲本和59个F1代个体进行了ISSR扩增,得到107个扩增位点,扩增的片段大小位于90~2100 bp之间,平均每个引物扩增7.64条条带,得到11种类型的带。 ISSR标记在送春×多花兰的F1代中表现出一定的多态性,分离频率为44.86％,分离位点有83.33％符合孟德尔1︰1或3︰1的分离规律,产生偏孟德尔分离的位点占12.50％,余下的4.17％属于特殊分离带型。可能导致后代变异的位点为偏孟德尔分离的6条带、缺失的8条带或新生成的2条带。聚类图中父本和母本与F1代个体间的遗传距离较远,59个杂交后代先聚集成一组,再同母本相聚为一组,最后才同父本聚在一起,59个杂种均偏母本型。送春与多花兰的杂交后代在植株形态、染色体、遗传物质方面都具备双亲特点,61个个体间的ISSR分子量标记结果和植株形态学特征都说明,59个F1代杂种包含送春和多花兰的遗传特性是真杂种;F1代杂种既有双亲的互补特征带,又有双亲的重组片断即产生新的特异带,这说明送春与多花兰的杂交后代具有遗传变异的特点。该研究结果可以有效地对杂交后代进行定向选择,为兰花的杂交育种提供了分子依据。     

马铃薯杂种F1的SSR鉴定

为选育抗黑痣病、高产优质的马铃薯新品种,选用引进品种‘大西洋’分别与‘陇薯6号’、‘陇薯7号’杂交,获得了杂种F1代,利用SSR标记技术对‘大西洋’与‘陇薯6号’的42个杂种F1、‘大西洋’与‘陇薯7号’的9个杂种F1单株进行了鉴定。从59对SSR引物中筛选出2对在亲本间存在差异、扩增稳定、条带清晰的引物S184和STM1049,用于‘大西洋’ב陇薯6号’杂种F1、‘大西洋’ב陇薯7号’杂种F1及其亲本的基因组DNA扩增。SSR带型分析显示,杂种F1的SSR带型呈双亲互补型、缺失型、父本型和母本型4类,依据带型特征鉴定出供试的51个马铃薯杂种F1单株均为真杂种,表明SSR分子标记技术用于马铃薯杂种真实性鉴定是可行的。该研究可为进一步开展马铃薯杂交后代目标性状优异株系选育提供依据。     

早世代稳定水稻的ISSR标记

2个早世代稳定亲本与4个普通水稻杂交,F2代出现了8个早世代稳定株系。遗传分析表明,稳定株系出现时杂交F1群体分离,同一组合的F2群体中既出现农艺性状整齐一致的稳定株系,又出现按孟德尔分离的株系。利用26个ISSR引物对F2稳定株系进行分子标记,结果表明稳定株系出现4种类型的标记带型：母本带型出现,父本带消失;父本带型出现,母本带消失;由双亲的部分标记带组合而成;双亲标记带型消失,而出现新的标记带型。没有出现由双亲标记带组合而成标记带型。ISSR引物900标记的2000bp标记带可以将稳定株系与普通水稻材料划分为两类群。     

甘蔗杂种的染色体和RAPD鉴定研究

采用体细胞染色体计数和RAPD (Random Amplified Polymorphism DNA) 分子标记的方法鉴定甘蔗与蔗茅属间杂交种F1的真实性.结果表明,杂种F1材料01/47、01/85、01/120的2n＝80～82,染色体遗传方式为n 2n.用110个随机引物进行RAPD扩增,63个引物可获得双亲的RAPD多态性,其中3个引物OPC-19、OPE-2、OPF-4可在杂种F1材料01/64和01/120的RAPD扩增标记中显示出双亲的特征谱带,分别为父本3500bp和母本1300bp、父本1350bp和母本900bp、父本550bp和母本900bp.     

亚洲棉与拟似棉远缘杂种的合成与鉴定

以亚洲棉为母本,野生种拟似棉为父本进行远缘杂交,人工辅助授粉合成杂种F1,验证F1杂种的真实性,以期进一步加倍成异源四倍体新种质。采用重复授粉和赤霉素保铃等措施提高杂交结铃率,对F1进行形态学及SSR分子标记鉴定。结果表明,F1杂种有典型的合子后生殖隔离现象,植株培养过程中伴随有杂种致死,F1杂种幼苗叶型大部分介于双亲之间且整体偏向于父本拟似棉;SSR分子标记结果显示杂种F1不仅扩增出双亲的互补带,还出现了双亲没有的新带;经过统计分析发现杂种F1中总的遗传成分比例母本占45.91%,父本占40.98%,新出现的组合带占13.11%。从分子水平证明了杂种的真实性,同时伴随的杂交过程也发生了AD基因组互作及遗传重组。     

利用SSR标记鉴定西瓜杂交种纯度的研究

以2个西瓜杂交品种(系)的种子黑公子和04-17及其亲本为材料,用SSR标记技术研究杂种与其双亲之间的扩增谱带多态性,以甄别真假杂种.结果发现,所试验的52对SSR引物中有13对引物分别在2个西瓜杂交种和其双亲之间存在扩增条带的多态性,表现为:多数SSR引物对自交系的扩增只出现1条带,但部分引物在某些自交系中扩增出2条带,杂交种条带均为父母本的互补型,很适合做杂交种纯度鉴定.用引物CMCT134b对黑公子和引物CMGA165对04-17进行了各100粒单种子SSR鉴定,所测纯度分别为96%和100%,与田间纯度95.6%和99.7%非常接近,表明SSR标记技术在西瓜杂交种子纯度室内快速检测中的应用前景.     

四倍体大燕麦×六倍体裸燕麦的杂种F1的产生及鉴定

本研究以四倍体大燕麦 (AvenamagnaL .)做母本 ,六倍体裸燕麦 (AvenanudaL .)做父本进行杂交 ,利用幼胚拯救技术获得了杂种F1,并对其后代形态特征进行了观察 ;对杂种F1同工酶图谱和DNA指纹图谱进行了分析。杂种F1形态特征偏亲本或介于双亲之间 ;同工酶研究表明多数F1具有双亲互补酶带 ;RAPD分析不同引物扩增产物F1呈共显性或偏父、偏母。这些结果表明F1为真杂种     

Relationship Between Gene Differential Expression of Leaves in Full Opening Flower Stages of Hybrids & Their Parents and Heterosis in Pest-resistant Cotton

cDNAs of leaves of 24 pest-resistant cotton (authorization) crosses and their parents in full opening flower stages were amplified and different bands were displayed by DDRT-PCR, with 45 primer combinations. The mean percentage of bands duplicated was 70.1%, which implied that there was a high proportion of pseudopositive fragments in the amplified cDNA. These pseudopositive bands can be reduced using duplicate PCR. Correlation analysis between differential gene expression and hybrid performance and heterosis showed that M4 (bands detected in one parent and F₁) was positively correlated with all yield traits, and significantly correlated with boll number; M2 (bands observed in one parent but not in F₁ and another parent) was negatively correlated with heterosis of boll number; and M3 (bands observed only in F₁) was positively correlated with heterosis of lint yield. These results showed that genes that had dominant and specific expression in top leaves of full opening flower stages were beneficial to yield formation and heterosis occurrence.     

Relationships of differential gene expression in leaves with heterosis and heterozygosity in a rice diallel cross

Using differential display analysis, we assessed the patterns of differential gene expression in hybrids relative to their parents in a diallel cross involving 8 elite rice lines. The analysis revealed several patterns of differential expression including: (1) bands present in one parent and F₁ but absent in the other parent, (2) bands observed in both parents but not in the F₁, (3) bands occurring in only one parent but not in the F₁ or the other parent, and, (4) bands detected only in the F₁ but in neither of the parents. Relationships between differential gene expression and heterosis and marker heterozygosity were evaluated using data for RFLPs, SSRs and a number of agronomic characters. The analysis showed that there was very little correlation between patterns of differential expression and the F₁ means for all six agronomic traits. Differentially expressed fragments that occurred only in one parent but not in the other parent or in F₁ in each of the respective crosses were positively correlated with heterosis and heterozygosity. And conversely, fragments that were detected in F₁s but in neither of the respective parents were negatively correlated with heterosis and heterozygosity. The remaining patterns of differential expression were not correlated with heterosis or heterozygosity. The relationships between the patterns of differential expression and heterosis observed in this study were not consistent with expectations based on dominance or overdominance hypotheses.     

Differential gene expression in liver of inbred chickens and their hybrid offspring

Differential display of mRNA was used to analyse the differences of gene expression in liver between chicken hybrids and their parents in a 4 x 4 diallel crosses in order to study the molecular basis of heterosis in chickens. The results indicated that patterns of gene expression in hybrids differ significantly from their parents. Four patterns of differential gene expression were revealed, which included: (i) bands only detected in the hybrid F1s (UNF1); (ii) bands only absent in the hybrid F1s (ABF1); (iii) bands only detected in the parental P1 or P2 lines (UNP1 and UNP2) and (iv) bands absent in the parental P1 or P2 lines (ABP1 and ABP2). In addition, correlations between patterns of gene expression and heterosis percentages of nine carcass traits of 8-week-old chickens were evaluated. Statistical results showed that negative correlations between heterosis percentages and the percentage of F1-specific bands (UNF1) were significant at P < 0.01 for breast muscle yield, leg muscle yield, wing weight, eviscerated weight and eviscerated weight with giblet of 8-week-old chickens, and at P < 0.05 for intermuscular fat width. Heterosis percentage was negatively correlated with ABP (bands present in the hybrid F1s and one parental line but absent in the other parental line, ABP1 and ABP2) for breast muscle yield, leg muscle yield, wing weight, eviscerated weight and eviscerated weight with giblet of 8-week-old chickens (P < 0.01). Bands detected only in the hybrid F1s but not in either of the parental lines (UNF1) and bands absent in parental P1 or P2 lines (which includes ABP1 and ABP2) may play important roles in chicken heterosis.     

种植密度对新疆高产棉花群体光合作用、冠层结构及产量形成的影响

 在新疆气候生态条件下,研究了种植密度对棉花（Gossypium hirsutum）群体光合作用、冠层结构和产量形成的影响,探讨了新疆棉花高产的生理机理及进一步提高产量的途径。结果表明：群体光合速率在盛铃期以前随密度增加明显增强,盛铃期以后,低密度6万株·hm-2的群体光合速率仍为最低,高密度30万株·hm-2群体光合速率迅速下降,中密度18万株·hm-2则保持较高水平。叶面积指数的变化与群体光合速率的变化相似,其峰值出现在盛铃期。冠层结构各指标的变化表现为,随密度增加平均叶簇倾角变大,株型变紧凑,但密度过大,群体散射辐射与直射辐射透过系数小,冠层结构不良,造成生育后期群体光合速率较快下降。增加密度能增加单位面积总铃数,但密度过高削弱了棉株个体发育,生育后期群体光合速率下降早,造成单铃重降低。群体总光合物质累积与群体光合速率在各生育时期呈显著正相关,籽棉产量与群体光合速率仅在盛铃期和吐絮期呈显著正相关;生产上要实现棉花高产及超高产,应使棉花生育前期群体光合速率稳定上升,至盛铃期达到高峰值,吐絮期群体光合速率保持较高水平     

新疆北部棉花冠层结构特征对滴灌定额的响应

在新疆北部地区自然生态条件下,采用棉花品种‘新陆早45号’为试验材料,设置5种滴灌定额处理(W₁:600 m³·hm^-2,W₂:540 m³·hm^-2,W₃:480 m³·hm^-2,W₄:420 m³·hm^-2,W₅:360 m³·hm^-2),研究了棉花叶面积指数、冠层开度、群体光吸收率、群体光合速率和产量对不同滴灌定额的响应.结果表明: 随着滴灌定额减少,棉花叶面积指数、群体光吸收率、群体光合速率均呈现降低趋势,其中W₁与W₂处理间的上述参数在盛蕾期至吐絮期均无显著差异;冠层开度则随滴灌定额减少呈增加的趋势.籽棉产量和皮棉产量均以W₁处理最高,分别为6549和2677 kg·hm^-2;W₂处理籽棉产量仅比W₁处理低6.5%,灌溉水利用效率较W₁处理高3.9%.相关分析表明,盛花期至盛铃期叶面积指数、群体光吸收率和群体光合速率均与籽棉产量呈显著或极显著正相关.因此,控制滴灌定额在540 m³·hm^-2有利于棉花在盛花至盛铃期保持较高的叶面积指数、增加冠层开度、保证光吸收率,进而增强群体光合速率,在不显著降低产量前提下提高灌溉水利用效率.     

A study of heterosis in upland cotton (Gossypium hirsutum L.)

Summary Heterosis (over mid parent) and useful heterosis (over commercial variety H14) estimates were obtained from a line x tester analysis of crosses involving thirteen diverse female parents with two locally adapted varieties H14 (local standard) and J34. Marked heterosis was observed for seed cotton yield, boll number and halo length. The values of positive heterosis and useful heterosis for seed cotton yield ranged from 28.1 to 87.0% and 20.1 to 45.5%, respectively. The overall study of heterosis revealed that female parents PRS-72 (USSR), 5904F (USSR) and MCU-5 (Madras Cambodian Uganda Selection, Coimbatore) were among the top three females, showing considerable heterosis in crosses with H14 and J34 for seed cotton yield and fibre properties. The practical difficulties in exploiting the phenomenon of heterosis and possible experimental approaches in upland cotton are discussed.     

Ven、K型小麦雄性不育系春性F1杂种的优势表现及与叶绿素含量和同工酶谱的关系

利用Ven、K型小麦雄性不育系与北方春性普通小麦杂交,研究了Ven、K型春性F1杂种的优势表现及其与叶绿素含量、同工酶谱的关系。结果表明：Ven型和K型杂种F1存在显著的个体杂种优质,在主要农艺性状中尤其以单株穗数、千粒重、单株生产力的杂种优势明显,其中单株穗数对单株生产力的贡献最大;相关分析表明：单株生产力与单株穗数呈正相关,相关系数为0.7122;与每穗粒数和千粒重的相关系数分别为－0.1183和0.4941。灌浆期旗叶、倒二叶叶绿素含量与千粒重的相关性最大,呈正相关。杂种F1优势强的组合其种子和苗期的过氧化物同工酶和酯酶的酶谱一般呈双亲互补型或“杂种型”酶带,该特征可作为杂种优势预测的指标。