The Karyotype Analysis Of Zea Species And The Genetic Studies Of The Aneuploid Hybrid Involving Maize And Zea Perennis

In this study, karyotypes from maize and teosinte of the current classification of Zea were investigated. Morphologic, cytological and crossability observation on the aneuploid which was obtained by open-pollinating maize-Zea perennis with Zea perennis were conducted. The main results were as follows:1. Cytological studies were carried out for maize and its relatives—teosinte. The results were as follows:All the materials are diploids with 2n=2x=20, except for Zea perennis(2n=4x=40). The variation of karyotypes within subsection and species(subspecies) were not observed. The chromosomes of all the materials were metacentric or submetacentric. Except for Zea perennis which had two pairs of satellites, the other species(subspecies) only had one pair, and the satellite was located on the short arm. The satellite of maize was positioned on the metacentric chromosome, while the satellites of teosinte were located on the submetacentric chromosome. The karyotype of all the taxa in Section Luxuriantes were "2A", while Section Zea were "2B" type.2. The karyotype of Zea perennis was studied systematically. The results showed that the number of its chromosome is 2n=40, the karyotype formula is 2n=4x=40=18m+22sm(4sat), which belongs to "2B" type, and there are two relatively clear pair of small satellite occurred on the chromosome 11 and 12, relative length ratio between the longest chromosome and shortest one is 1.94, the proportion of chromosome of arm ration>2 is 0.3, the index of asymmetry is 62.46. It showed that Zea perennis and Zea diploperennis were two separate species, it did not support the point that Zea perennis was evolved from Zea diploperennis.3. The observation of morphologic, cytological and crossability on the aneuploid were conducted. The results were as follows:(1) It showed that many morphological characters of the two parents, maize and Zea perennis, were observed on MDT. The MDT was perennial and luxurious. It was almost completely male sterile but partially female fertile.(2) The cytological results showed that the number of chromosome is 2n=39, it is an aneuploid. The chromosomal behavior of MDT's pollen mother cells (PMCs) in meiosis were complex and there were univalent, trivalent and tetravalent as well as bivalent at the diakinesis of PMCs in the aneuploid. And the average of the meiotic configuration of the 135 PMCs accounted at diakinesis was 2.93Ⅳ+2.74Ⅲ+9.36Ⅱ+3.08Ⅰ. There were irregularities in every other phase of meiosis, such as abnormal distribution and unequal segregation of chromosomes.(3) The GISH results showed that 9 chromosomes of them were from Zea mays ssp. mays. (yellow color), while the other 30 chromosomes were from Zea perennis(red color).(4) Morphologic and cytological observation on MDT×maize and MDT×Zea perennis were conducted. Results showed that MDT×maize are maize-like. Frequency of their cells with 29,30,31, and the chromosome with the most frequent number of 30. The pollen fertility, crossability, spike row number were gradually increased compared with the MDT. The phenotypes of MDT×Zea perennis were similar to MDT, but the number of their tillers were less than MDT, the plants were perennial and luxurious, and the character of their ear and tassel were similar to MDT, the higher frequency of the number of their somatic chromosome were 39 and 40.(5) In conclusion, the perennial aneuploid material provides a novel germplasm resources for the introgression of Zea perennis into maize, it start a new way for the construction of maize(Zea perennis) family.