Chromosome Manipulation Of Aneuploid Hybrid From Maize×Zea Perennis As A Bridge For Gene Introgression Between Species

The sterility of F1from Z. mays×Z. perennis serious hindered gene flow between two species. Previous study made by our research group proved that a special aneuploid plant named MDT was got by distant hybridization and could be used to broke through the obstacle between Z. mays and Z. perennis. A series of backcross progenies of MDT were studied in this research using a variety of morphological, cellular, and molecular techniques. Meanwhile, the perennial characteristic and alien chromosome behaviour in these progenies were analyzed. The main results were as follows:1. The GISH results indicated that genomic in situ hybridization (GISH) could effectively differentiate chromosomes or chromosomal regions of maize and Z. perennis in hybrid plant when the blocking rate was1:80.2. Phenotypic identification and perennial characteristic of the first backcross generation with maize was studied. The result indicated that8progenies were survived in the field and1of them was perennial plant, the others were annual plants. The Phenotype of annual plants showed an intermediate phenotype between maize and Z. perennis. Chromosome number of the8progenies was between29and31. Maize genome was used as prob in GISH, and the yellow signal was maize chromosome(M) while red for Z. perennis(P). The result showed that the chromosome composition of one maize-type annual plant was10M+20P. Lagging chromosomes as well as unequal chromosome distribution were observed in meiosis of perennial plant’s pollen mother cells (PMCs) and the karyotype formula was2n=5.5Ⅰ+6.88Ⅱ+2.25Ⅲ+1Ⅳ. A few seeds were obtained by backcross the perennial plant with maize parent.3. Morphologic, cytological observation and GISH on the backcross generation of perennial plant with maize was studied. The morphological results showed that three kinds of phenotype appeared in the progenies including maize type, middle type and wild type. The cytological results showed that the number of chromosome varied from20to29. Three individual plants (B6,2n=20; B7,2n=21; B8,2n=21) were selected from perennial X maize, which most likely to be new kind of substitution line and additional line. The GISH results showed that2plants (B7,B8) which were new kinds of substitution line and additional line contained2-3teosinte chromosomes. The other one (B6) contained two fragments of Z. perennis, which was a new type of translocation line.4. Morphologic, cytological observation and molecular marker (SSR) on MDTXZ. perennis were conducted. The result indicated that there was no significant difference of filed characteristics in MDTXZ. perennis, and all of them had perennial feature. The hybrid progenies had strong cold tolerance. MDT×Z. perennis had a strong growth potential compared with Z. perennis. Analysis of variance indicated significant differences between MDT×Z. perennis and Z. perennis in plant height, leaf length, leaf width as well as stem width which means distant hybridization being a method improved wild relatives. Two typical individual plants were selected from MDT×Z. perennis in order to reveal the chromosome composition via GISH. The results illustrated that3maize chromosomes existed in one plant and2in another, the first identified whole maize chromosome transferred in to Z. perennis. Alien germplasm from MDT×Z. perennis were identified by molecular marker SSR.10pairs of microsatellite primers (one pair in each maize chromosome) was selected and the result showed that maize chromosome4,8and10may contained in one, and any two of maize chromosome4,6and10may contained in another.