Anaerobiosis‐mediated early transcriptional and translational responses in rice (Oryza sativa L.) coleoptiles and roots

Abstract

To study the transcriptional and translational responses that occur in rice (Oryza sativa L., cv. Arborio) coleoptiles and roots during the first hours of anoxia, we analysed the patterns of in vitro translational products and in vivo labelled newly synthesized proteins obtained from both organs grown in the presence or absence of O2. Analysis of the protein pattern obtained from nuclear‐enriched sub‐cellular fractions showed the enhancement of the synthesis of several proteins with molecular weights of 67–62, 54 and 34 kD. In the cytoplasmic‐enriched subcellular fractions, we found that the synthesis of polypeptides of relatively low molecular weight (13–16 kD) was strongly induced by anaerobiosis. In vitro translation analysis showed that this enhancement was mainly due to a rapid increase in the level of the corresponding mRNA species. These low‐molecular‐weight translational products were already detected after 1h of anoxia in both rice roots and rice coleoptiles, but remained undetectable in aerobically grown organs. Additional anaerobic‐specific transcriptional and translational changes were also observed. In particular, a specific reduction in the level of mRNAs coding for polypeptides of 38 kD occurred in both roots and coleoptiles after only 1 h of anoxia.

Overexpression of the rice Osmyb4 gene increases chilling and freezing tolerance of Arabidopsis thaliana plants

“…Germination was carried out for 60 h on sterile wet paper filters in Petri dishes kept in the dark at 29°C. Seedlings were subjected to several treatments: high salinity, 250 m m NaCl for 5 h; heat temperature, 40°C for 5 h; cold, 4°C for 5 h; drought, transferred on Whatman 3MM paper in a sterile Petri dish for 5 h; ABA, 0.1 m m abscisic acid for 5 h; IAA, 0.1 m m indolacetic acid for 2 h; light, exposed to fluorescent light for 2 h. For the anaerobic treatment, coleoptile segments of the 3‐day‐old seedlings were subjected to 2 h of anoxia, fluxing N 2 in the Heller medium as previously described by Breviario et al . (1994); for the anaerobic germination, rice was germinated and grown as described by Breviario et al .…”

Isolation and Transcription Profiling of Low-O2 Stress-Associated cDNA Clones from the Flooding-stress-tolerant FR13A Rice Genotype

“…Plants respond to low O 2 -stress treatment through specific alterations in gene expression. The regulation of gene expression under low O 2 conditions is noted to be at both transcriptional (Sachs et al, 1980;Breviario et al, 1994) and translational levels (Sachs et al, 1980;Bailey-Serres and Freeling, 1990). The proteins specifically upregulated upon anaerobic stress are referred to as anaerobic proteins (ANPs), which mainly comprise metabolic pathway enzymes.…”

The Product of the Rice myb7 Unspliced mRNA Dimerizes with the Maize Leucine Zipper Opaque2 and Stimulates Its Activity in a Transient Expression Assay

“…Maintenance of in vitro shoot cultures of Nicotiana tabacum (cultivar Petit-Havana, SRI) and preparation of apical segments from rice (cultivar Arborio) roots and coleoptiles were described previously (23,24).…”

“…Cytoplasmic and nuclei-enriched subcellular fractions from frozen root and coleoptile segments and from transformed protoplasts were isolated as described (24) and then loaded on discontinuous Percoll gradient to obtain a pure nuclear fraction (35). The purity of the nuclear preparations was assayed by UV fluorescence microscopy after DAPI (1 g/ml) staining.…”