Low temperature affects the processing pattern and RNA editing status of the mitochondrial cox2 transcripts in wheat

Abstract

We investigated the effects of low temperature on the expression of mitochondria-encoded genes in wheat. During the course of our study, we found that the transcriptional pattern of cox2 was affected by low temperature. Northern blot analysis indicated that the precursor transcript before intron splicing was clearly increased by cold, although the level of mature message was not changed. We also found that cold treatment severely suppressed RNA editing at intron-binding site 1 of the precursor transcript, which plays an important role in intron splicing. These results suggest that low temperature could affect the post-transcriptional regulation of wheat mitochondrial cox2 transcripts, i.e. intron splicing and/or RNA editing.

Post-transcriptional Regulation in Mitochondria of Rice and Wheat at Low Temperatures

“…This does not contradict the increases in cytochrome pathway activity in cold acclimatable plants 3,79 . The RNA editing status of wheat mitochondria at low temperatures also resembles that in rice 40 . The editing frequency of site 9 of wheat intron-containing cox2 transcripts, which is located in IBS1 and corresponds to the cold-sensitive editing site in rice cox2, was very low under cold conditions, although about 70% were edited under 20/15˚C (day/night) 40 (Fig.…”

“…The increase of accumulation reportedly started after some days of treatment in wheat, which resembles rice 39,40,41 . When some varieties were compared, the increase in winter wheat varieties tended to start later than that in spring ones, which suggests that this phenomenon is linked to cold tolerance 39 .…”

“…The accumulation of intron-containing transcripts of cox2 and other mitochondria-encoded genes has been shown to increase in wheat treated at low temperatures (2/0.5˚C (day/night)) 39,40 , as well as the case in rice ( Table 1). The increase of accumulation reportedly started after some days of treatment in wheat, which resembles rice 39,40,41 .…”

“…3). When the RNA editing status of cox2 exon 1 in two species is compared, the frequency of all editing sites decreases in wheat after treatment at 2/0.5˚C, while that of only site 9 decreases markedly in rice after 12˚C treatment 40,41 (Fig. 3).…”

“…Interestingly, similar phenomena in the plastid are reported: some editing sites of tobacco ndhB are sensitive to a high temperature of 42˚C and antibiotics 28,29 , which suggests that some editing factors in either organelle are temperature-sensitive. , and Kurihara-Yonemoto and Handa 40 . )…”