Hajime Ohyanagi
,
King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
Isaiah Pabuayon
,
Department of Plant and Soil Science, Texas Tech University, Lubbock, TX
Masahiro Fujita
,
Plant Genetics Laboratory, National Institute of Genetics, Mishima, Japan
Bipush Osti
,
Department of Plant and Soil Science, Texas Tech University, Lubbock, TX
Yusuke Kakei
,
Yokohama City University, Yokohama, Kanagawa, Japan
Atsushi Toyoda
,
Comparative Genomics laboratory, NIG, ROIS, Mishima, Japan
Asao Fujiyama
,
Comparative Genomics Laboratory, National Institute of Genetics, ROIS, Shizuoka, Japan
Matthew R. Shenton
,
National Institute of Genetics, Mishima, Shizuoka, Japan
Nori Kurata
,
NIG, ROIS, Shizuoka, Japan
Benildo G. de los Reyes
,
Department of Plant and Soil Science, Texas Tech University, Lubbock, TX
The diploid genomes of
Oryza sativa (AA) and
Oryza officinalis (CC) differ in size, sequence complexity, and gene content. The biological significance of their genomic differences in terms of relative potentials for abiotic stress tolerance is unknown. In our earlier studies, we observed that despite a comparable cold sensitivity in these species, certain backcross lines derived from
O. sativa x
O. officinalis hybrids segregated transgressively for cold tolerance. Inspired by such observation and by the knowledge that complementation and epistasis configure transgressive phenotypes, we compared the cold stress response transcriptomes of the reference
O. sativa ssp. Japonica and
O. officinalis Acc. 100896
, as a first step towards understanding the basis of transgressive segregation. Our specific aim was to uncover complementary transcriptional networks that may illuminate the combined potentials of each species for transgressive cold tolerance phenotypes.
We found a high degree of network conservation across AA and CC by virtue of similar patterns for ABA-dependent and DREB/CBF response pathways. However, despite such strong similarities, AA and CC transcriptomes were highlighted by distinct subsets of regulatory transcription factors that define their unique network signatures. Major networks regulated by BES1 transcriptional regulator associated with brassinosteroid signaling define a critical aspect of divergence, being non-functional in AA. Here we describe the composition of BES1-mediated network as a unique signature of O. officinalis cold stress response pathway. We also discuss the predicted physiological outcomes of such network and our insights on its potential for enhancing cold tolerance of O. sativa x O. officinalis recombinants.
