Tang Ji-hua

Identification of Heterotic Loci for Yield and Ear Traits Using CSSL Test Population in Maize

Heterosis plays an important role in enhancing crop yield and quality. Dissecting the genetic basis of heterosis can promote hybrid maize selection, however it is unclear up to now. In this study, a set of chromosome segment substitution lines (CSSLs) population, which was constructed using the inbred line lx9801 as the receptor parent and the inbred line Chang 7-2 as the donor parent, was crossed with the inbred line T7296 to construct the corresponding test population. The test population was used to identify the heterotic loci (HL) for grain yield and ear traits in maize, which showed significant difference in heterosis between the corresponding chromosomal region of the inbred line Chang 7-2 and lx9801 as well as the test inbred line T7296. A total of 64 HL were identified for gain yield and ear traits, and among them 23 HL were identified at the two environments simul- taneously, including 4 HL for ear length, 4 HL for ear width, 4 HL for row number, 7 HL for kernels per row, and 4 HL for grain yield. Additionally, the HL for both grain yield and its components simultaneously were found on many chromosomal regions. This study could offer a basic material for thoroughly dissecting the genetic basis of heterosis for grain yield and its components in maize.

Proteome Changes in Maize Embryo (Zea mays L) Induced by Ion Beam Implantation Treatment

Low energy ion beam implantation was applied to the maize (Zea mays L) embryo proteome using two-dimensional gel electrophoresis. Protein profile analysis detected more than 1100 protein spots, 72 of which were determined to be expressed differently in the treated and control (not exposed to ion beam implantation) embryos. Of the 72 protein spots, 53 were up-regulated in the control and 19 were more abundantly expressed in the ion beam-treated embryos. The spots of up- or down-regulated proteins were identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). Among the identified proteins, 11 were up-regulated in the treated embryos. Four of these up-regulated proteins were antioxidant molecules, three were related to stress response, two to sugar metabolism and two were associated with heat shock response. Of the five proteins up-regulated in the control embryos, three were functionally related to carbohydrate metabolism; the functions of the remaining two proteins were unknown. The data collected during this study indicate that treatment of maize embryos with low energy ion beam implantation induces changes in stress tolerance enzymes/proteins, possibly as a result of alterations in metabolism.

Mapping Unequal Crossing over Hotspot Region of Simple Sequence Repeat in Maize

The polymorphism of simple sequence repeat(SSR) in biological genome is one result of unequal crossing over for homologous chromosomes;therefore it has theoretical importance in clarifying the hotspot regions of unequal crossing over.A set of recombinant inbred lines(RILs) population that derived form an elite hybrid Yuyu 22 was used in this study,its genetic components of the population was analyzed by means of SSR analysis,and 40 unequal crossing over SSR markers were found.The frequency of the unequal crossing over in the RIL population was 0.34-14.63%,with 10-2-10-1 frequency per generation,and the(AG)n repeat SSR markers accounted for 58.3%.There were 31 unequal crossing over markers locating on 11 chromosomal hotspot regions,distributing on 10 chromosomes except for chromosome 9,including two unequal crossing over hotspot regions each in chromosomes 3 and 5.