Genetic Basis Of The Formation Of Mixed Genomes In Octoploid Trititrigia And Identification Of Trititrigia Germplasm

Thinopyrum intermedium (2n=6x=42, EeEeEbEbStSt or JJJSJSStSt) is one of theimportant genetic resources for wheat genetic improvement, many kinds of Trititrigiagermplasm lines which were developed from the progeny of common wheat and Th.intermedium are an important bridge materials for transferring excellent Thinopyrum gene tocommon wheat, are also basis materials of gene discovery and genetic research. In the presentstudy, molecular markers, genomic in situ hybridization and genome comparison analysiswere used to study the formation mechanism of mixed genomes of octoploid Trititrigia, inorder to analyse the genetic basis of the octoploid Trititrigia species and types; And using themethods of morphology, cytology, molecular markers and genomic in situ hybridization, theTrititrigia germplasm lines with good characters and features were identified and analysed, inorder to clarify its main characteristics, characters of cytological features and chromosomestructure. The main research results were as following:1. By methods of cytology and genomic in situ hybridization (GISH), ten octoploidTrititrigia were analysed on chromosome number of root tip cells (RTC), chromosomeconfiguration of mediumterm I pollen mother cell meiosis (PMC MI) and constitution of alienchromosomes. The octoploid Trititrigia shannong TE256, shannong TE259, shannong TE261,shannong TE262, shannong TE263, shannong TE265, shannong TE266, shannong TE267-1,shannong TE270and shannong TE274all had intact wheat genome chromosomes plus14Th.intermedium chromosomes, and their constitutions of alien chromosomes were2St+8JS+2J+2J-St,2St+8JS+4J,2St+8JS+2J+2J-St,2St+8JS+2J+2J-St,2St+8JS+2J+2J-St,6St+4JS+2J+2J-St,4St+6JS+2J+2J-St,2St+8JS+4J,2St+8JS+4J and4St+6JS+4J. The alien chromosomes in each octoploid Trititrigia were all from differentgenomes of Th. intermedium, and mostly consisting of JS(Ee) and J (Eb) genomes.2. In total5760primers were used to amplify the genomic DNA of Th. intermedium, Th.elongatum, Th. bessarabicum and Pseudoroegneria strigosa. The obtained polymorphicprimers of Th. intermedium were used to amplify the genomic DNA of Th. intermedium, Th.elongatum, Th. bessarabicum, Pseudoroegneria strigosa and common wheat cultivarYannong15. The results showed that440,430, and430special molecular markers wereeffectively mapped to the Ee, Eb, and St genomes, respectively. Using two sets of disomicaddition lines (DA1Ee-DA7Eeand DA1Eb-DA7Eb),142and119special molecular markers were effectively mapped to the specific Eeand Ebchromosomes, respectively. These genomicspecific molecular markers will be useful in comparative gene mapping, chromosomeevolutionary analysis, taxonomic studies, gene introgression, and cultivar identification.3. Using the Ee(JS), Eb(J) and St genome-specific molecular markers of Th. intermedium,10octoploid Trititrigia, Th. intermedium and yannong15were analysed in order to obtain thegenome or chromosome-specific molecular markers of Th. intermedium in octoploidTrititrigia. The results showed that the special molecular markers of each octoploid Trititrigiawere mostly from Eeand Ebgenomes. Further, the added Th. intermedium chromosomes inthe ten octoploid Trititrigia were all confirmed to be mixed genomes, and mostly were fromEeand Ebgenomes, consistenting with the results of GISH. According to the results ofspecific molecular marker and GISH, the added alien chromosomes of Shannong TE256,Shannong TE259, Shannong TE261, Shannong TE262, Shannong TE263, Shannong TE267-1and Shannong TE270were2Ee,4Ee,5Ee,6Ee,7Eeand5Eb; Shannong TE265were2Ee,5Ee,7Eeand5Eb; TE266were2Ee,4Ee,5Ee,7Eeand5Eb; Shannong TE274were2Ee,5Ee,6Ee,7Eeand5Eb.4. By methods of morphology and cytology,171Trititrigia germplasm lines developedfrom the progenies between Th. intermedium and common wheat Yannong15had beenidentified. Sixty-three Trititrigia germplasm lines of major characteristics and cytologicalcharacteristic were obtained, providing references for the subsequent use. The63Trititrigiagermplasm lines included45octoploid Trititrigia,2disomic alien addition lines and16disomic substitution lines.5. By resistance identification of powdery mildew resistance in seedling and adult,drought resistance in seedling and salt tolerence in seedling, octoploid TrititrigiaShannongTE256, ShannongTE265and ShannongTE267-1were analysed. The results werethat they were all good resistance to powdery mildew, drought and tolerance to salt, and theresistance of them were inferred from Th. intermedium.6. Combining the methods of molecular markers and GISH, SN100109was a wheat-Th.intermedium disomic addition line, containing a pair of2Eechromosomes from Th.intermedium, and the powdery mildew resistance gene was located on the2Eechromosomes.SN0946was a wheat-Th. intermedium disomic substitution line, with a pair of chromosomesfrom common wheat substituted by a pair of2Eechromosomes from Th. intermedium, and thepowdery mildew resistance gene was located on the2Eechromosomes.