Chromosome Based Strategies to Decipher the Structure and Evolution of the Hexaploid Wheat Genome： Chromosome 3B, a Case Study

With 17% of all crop area, wheat is the staple food for 40% of the world＇s population. Improvement in bread wheat quality and yield in the context of sustainable agriculture is needed in the next decades to meet human needs by 2050. To accelerate gene discovery, marker assisted selection and the exploitation of genetic diversity in wheat, significant advances must be achieved in the understanding of the structure, function and evolution of the wheat genome.     

Identification of novel secaloindoline-a and secaloindoline-b alleles in CIMMYT hexaploid triticale lines

To characterize kernel hardness, an important trait in triticale breeding, and to identify secaloindoline alleles present in hexaploid triticale lines developed at International Maize and Wheat Improvement Center (CIMMYT) a total of 171 secondary hexaploid lines were analyzed for grain hardness using the Single Kernel Characterization System. They showed a large spectrum of kernel hardness types, from very soft to very hard, with values ranging from 8.6 to 84.9. The occurrence of starch granule-associated friabilin was studied in 30 lines, including 10 hard, 9 mixed and 11 soft genotypes. All soft lines displayed a high level of friabilin, whereas the hard lines showed almost no friabilin, indicating that friabilin is directly involved in the formation of grain texture in secondary hexaploid triticales. Two novel secaloindoline alleles were identified and designated as Sina-R1b and Sinb-R1c. Compared with SINAa, the deduced amino acid sequence of SINAb showed a Trp to Arg substitution at position 44. SINBc had a Gly to Ser substitution at position 78 and a Gly to Arg substitution at position 115, as well as a Cys insertion in the signal peptide, in comparison to SINBa. The novel alleles Sina-R1b and Sinb-R1c were detected in both the soft and hard triticale lines.     

渗透胁迫对六倍体小黑麦幼苗叶片相对含水量的影响

利用不同浓度的PEG-6000(0、10%、20%、30%、40%)胁迫处理,不同品种的六倍体小黑麦幼苗叶片相对含水量都有所下降。在低浓度胁迫下,下降缓慢,随着浓度的提高,下降程度逐渐增强;不同品种对PEG-6000胁迫响应不同,随着胁迫浓度的提高,品种S6、S7、S9幼苗叶片相对含水量下降幅度较小,而S1、S5、S8、S10下降幅度较大;另一方面,在30%PEG-6000溶液胁迫处理下,随着时间的延长,不同品种的六倍体小黑麦幼苗叶片相对含水量逐渐下降,品种S4、S5、S6、S7、S9下降幅度较小,而品种S8、S3下降幅度较大。综合分析发现小黑麦品种S6、S7、S9在不同浓度的PEG-6000胁迫下和同一浓度不同的胁迫时间叶片相对含水量都高,即保水能力强,因而抗旱性较强;而S8相反。     

柑橘种间六倍体体细胞杂种开花及其花粉育性

 二倍体锦橙+种间四倍体体细胞杂种HR (哈姆林甜橙+ 粗柠檬) 的种间六倍体体细胞杂种植株移入温室7年后(即2004年) , 有1株六倍体首次开花, 花粉染色活力40.8% , 花粉萌发率3.7%;2006年该植株再次开花, 花粉染色活力为20.3%。由于自然界中没有柑橘六倍体, 本研究是人工的方法创造出可育的柑橘六倍体体细胞杂种植株的首例报道。     

Polyploidization of Miscanthus sinensis and Miscanthus x giganteus by plant colchicine treatment

The purpose of this study was to find a suitable treatment combination that would effectively induce polyploids in the grass species from the genus Miscanthus. In the experiments, the combinations of two concentrations of colchicine, three options of supplementing the colchicine solution with additional substances and three exposure times were tested. The experiments were conducted using diploid and triploid genotypes belonging to M. sinensis and M. x giganteus. Colchicine treatments generated 50 tetraploids in four diploid genotypes and two hexaploids in one out of two triploid genotypes. Induction of polyploids by plant colchicine treatment was highly dependent on genotype. In three out of six genotypes, some tested combinations resulted around 20% of polyploidization effectiveness. Re-examination of obtained material confirmed that 95% of plants are fully solid polyploids. Generated tetraploids were fertile. Polyploidization by ex vitro colchicine treatment of Miscanthus plants can be useful in plant breeding, particularly because its advantages in saving time.     

六倍体小黑麦种质资源遗传多样性分析

利用RAPD标记对10份六倍体小黑麦、1份普通小麦和1份黑麦种质资源遗传多样性进行了分析,19个RAPD引物中,有10个引物(52.63%)可扩增出清晰且具多态性的条带。10个引物共产生385条DNA片段,其中384条具有多态性,多态性比率为99.74%,不同引物扩增带数变幅为8~71条,平均为38.5条,扩增产物的片段大小为298~3 054 bp,材料间的遗传距离变化范围在0.724~0.833之间。对12份供试材料的遗传关系进行聚类分析,在平均GD值0.77水平上可将12份供试材料分为3类。研究结果为将六倍体小黑麦的优良基因导入到普通小麦中提供了理论依据。     

六倍体小黑麦基于农艺性状和品质性状的多样性分析

为明确从国际玉米小麦改良中心(CIMMYT)引进的111份六倍体小黑麦的遗传多样性特点,为其有效利用提供参考依据,对其农艺性状和品质性状特点进行了多样性分析。结果表明：6个农艺性状的平均变异系数为16.94%,平均多样性指数是1.96,小穗数/穗、穗长和千粒重的多样性指数均高于2.00;10个品质性状的平均变异系数为8.60%,平均多样性指数是1.94,吸水率、面团稳定时间的多样性指数均高于2.00。结论：111份六倍体小黑麦的农艺性状和品质性状表现出较大的差异,具有较丰富的多样性。     

普通小麦穗部性状的配合力与遗传模型分析

选用穗部性状典型的6个普通小麦(T.aestivumL.)材料,采用6×6不完全双列杂交法分析了穗长、结实小穗数、小穗粒数、穗粒数、千粒重和单穗重的杂种优势、配合力、遗传模型及适宜的选择世代。结果表明,千粒重、穗长、穗粒数及单穗重具有较高的杂种优势;穗长、结实小穗数、穗粒数和单穗重一般配合力高,前2个性状在F₂～F₃代选择有效,后2个性状在F₄～F₅代选择有效;每小穗粒数和千粒重特殊配合力高,在F₆～F₇代选择有效;6性状遗传均符合加性-显性模型。此外,84加79与V8164柱部性状协调,一般配合力高,可作为大穗材料在育种中应用。     

显性雄性不育硬粒小麦（Triticum durum）和二粒小麦（Triticum dicoccum）选育

用已育成的显性雄性不育六倍体小黑麦为母本分别与硬粒小麦、二粒小麦及黑麦杂交,并每代选不育株用原父本回交。结果表明,来源于太谷核不育小麦4D染色体上的Ms2（Tal）基因已易位到A或B染色体组的某一条染色体上。从而育成了显性核不育硬粒小麦和二粒小麦。     

六倍体小黑麦灌浆期抗旱性分析

采用盆栽在六倍体小黑麦灌浆期控水模拟干旱,分析干旱对各个农艺性状指标的影响,然后采用模糊隶属函数与抗旱系数相结合的方法对品种灌浆期的抗旱性进行综合分析,再利用灰色关联度分析各个形态指标与抗旱性的关系,结果表明：（1）灌浆期水分胁迫下所有品种都表现出株高降低,穗长变短,单株粒重、千粒重下降,每穗总小穗数、主茎穗粒数减少,而且与对照之间达差异显著或极显著;（2）品种“Tornado”对灌浆期干旱具有强的抗性,可作为今后小麦抗旱育种的种质资源;（3）单株粒重、主茎穗粒数、千粒重与抗旱性关联度大,可作为灌浆期抗旱形态指标