Differential Gene Expression Between Wheat (Triticum Aestivum L.) Hybrids And Their Parental Inbreds And Its Relationship To Molecular Basis Of Heterosis

1 Heterosis in eight root traits measured under nutrition solution culture was estimated at jointing stage in a wheat diallel cross involving 20 hybrids and nine parents, the results indicated that higher level of heterosis is more frequently observed in root traits than in above-ground agronomic traits among these hybrids. It was found that mid-parent heterosis (MPH) in 122 out of 160 hybrid/trait are greater than zero, while best-parent heterosis (BPH) in 101 out of 160 hybrid/trait are greater than zero.2 Improved differential display technique was used to analyze alterations in gene expression between hybrid and parents in roots at jointing stage, with the purpose of determining the relationship between differential expression patterns and heterosis in eight root system traits. Four differential expression patterns were observed. It was found that BPnF1 pattern was negatively correlated with both MPH and BPH in root volume; UPnF1 was negatively correlated with both MPH and BPH in root volume and root dry weight. FinBP and UPF1 patterns were not correlated with either MPH or BPH in any root traits. Patterns of differential gene expression were found to be significantly correlated with heterosis in agronomic traits: BPnF1 was positively correlated with heterosis in spike length, biomass and root/shoot, UPnF1 was positively correlated with heterosis in spike length and biomass, FlnBP was found to be positively correlated with heterosis in root/shoot, and UPFI was positively correlated with heterosis in 1000-kernel weight.3 fifty two differentially expressed cDNAs in cross 3338/6554 were cloned and sequenced, and their expression patterns were confirmed by reverse-Northern dot blot analysis. Sequence analysis and database searches revealed that among these cDNA clones, 23 have homology to known proteins, including genes encoding synthetase, aldolase, oxidoreductaseandpolymerase, enzymes involved in transcription and translation, membrane transporters and regulator factors.4 Five sequences including complete ORF were cloned by in silico cloning and PCR amplification by primers designed using in silico cloning results. Bio-informatic analysis showed that the sequences had their own domains with related function.5 Transgenic analysis identified that our phytochelatin-synthetase-like gene had potential to protect bacterial and Arabidopsis from existence of CdCl2.Furthermore, we also find that with no heavy metal the overexpressed transgenic plants had longer root than wild root.