Triticum turgidum subsp. durum x Aegilops tauschii
Ontology highlight
ABSTRACT: Deep sequencing of small RNAs in grass-clump dwarf phenotype of abnormal growth triploids in interspecific crosses between tetraploid wheat and Aegilops tauschii
Project description:RNA sequencing-based bulked segregant analysis of synthetic hexaploidy wheat derived from interspecific crosses between tetraploid wheat and Aegilops tauschii
Project description:We have employed whole genome microarray expression profiling as a discovery platform to identify genes to alter the transcript accumulation levels in hybrid necrosis-showing plants, which are triploid hybrids crossed between tetraploid wheat and diploid wheat progenitor Aegilops tauschii. Of the up-regulated genes, defense-related genes were most frequently found, whereas photosythesis-related genes down-regulated in the type I necrosis line. To validate the microarray data, RT-PCR and quantitative RT-PCR analyses for 22 selected genes were performed. Of the examined 15 up-regulated and 7 down-regulated genes, the expression pattern of only one down-regulated gene was inconsistent with the microarray data. Together with cytological analysis of the necrotic tissues, the microarray analysis strongly suggests that an autoimmune response might be triggered by intergenomic incompatibility between the AB and D genomes in type I necrosis, and that genetically programmed cell death could be regarded as a hypersensitive response-like cell death similar to that observed in Arabidopsis intraspecific and Nicotiana interspecific hybrids.
Project description:Common wheat is an allohexaploid species, derived through endoreduplication of an inter-specific triploid hybrid produced from a cross between cultivated tetraploid wheat and the wild diploid relative Aegilops tauschii Coss. Hybrid incompatibilities, including hybrid necrosis, have been observed in triploid wheat hybrids. A limited number of Ae. tauschii accessions show hybrid lethality in triploid hybrids crossed with tetraploid wheat due to developmental arrest at the early seedling stage, which is termed severe growth abortion (SGA). Despite the potential severity of this condition, the genetic mechanisms underlying SGA are not well understood. We conducted comparative analyses of gene expression profiles in crown tissues to characterize developmental arrest in triploid hybrids displaying SGA. A number of defense-related genes were highly up-regulated, whereas many transcription factor genes, such as the KNOTTED1-type homeobox gene, which function in shoot apical meristem (SAM) and leaf primordia, were down-regulated in the crown tissues of SGA plants. Transcript accumulation levels of cell cycle-related genes were also markedly reduced in SGA plants, and no histone H4-expressing cells were observed in the SAM of SGA hybrid plants. Our findings demonstrate that SGA shows unique features among other types of abnormal growth phenotypes, such as type II and III necrosis.