Degradation of mitochondrial structure and deficiency of complex I were associated with the transgenic CMS of rice

BACKGROUND: Mitochondria play a significant role in plant cytoplasmic male sterility (CMS). In our previous study, mitochondrial complex I genes, nad4, nad5, and nad7 showed polymorphisms between the transgenic CMS line M2BS and its wild type M2B. The sterility mechanism of the M2BS at cytological, physiological, biochemical, and molecular level is not clear. RESULTS: Cytological observation showed that the anthers were light yellow, fissured, invalid in KI-I2, and full of irregularly typical abortion pollen grains in M2BS. Transmission electron microscopic (TEM) observation revealed no nucleus and degraded mitochondria with obscure cristae in anther cells of M2BS. The results of staining for H2O2 presented a large number of electron dense precipitates (edp) in intercellular space of anther cells of M2BS at anthesis. Moreover, the anther respiration rate and complex I activity of M2BS were significantly lower than those of wild type M2B during pollen development. Furthermore, RNA editing results showed only nad7 presented partially edited at 534th nucleotides. The expression of nad5 and nad7 revealed significant differences between M2B and M2BS. CONCLUSIONS: Our data demonstrated that mitochondrial structural degradation and complex I deficiency might be associated with transgenic CMS of rice.

Molecular cloning and subcellular localization of six HDACs and their roles in response to salt and drought stress in kenaf (Hibiscus cannabinus L)

BACKGROUND: Histone acetylation is an important epigenetic modification that regulates gene activity in response to stress. Histone acetylation levels are reversibly regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs). The imperative roles of HDACs in gene transcription, transcriptional regulation, growth and responses to stressful environment have been widely investigated in Arabidopsis. However, data regarding HDACs in kenaf crop has not been disclosed yet. RESULTS: In this study, six HDACs genes (HcHDA2, HcHDA6, HcHDA8, HcHDA9, HcHDA19, and HcSRT2) were isolated and characterized. Phylogenetic tree revealed that these HcHDACs shared high degree of sequence homology with those of Gossypium arboreum. Subcellular localization analysis showed that GFP-tagged HcHDA2 and HcHDA8 were predominantly localized in the nucleus, HcHDA6 and HcHDA19 in nucleus and cytosol. The HcHDA9 was found in both nucleus and plasma membranes. Real-time quantitative PCR showed that the six HcHDACs genes were expressed with distinct expression patterns across plant tissues. Furthermore, we determined differential accumulation of HcHDACs transcripts under salt and drought treatments, indicating that these enzymes may participate in the biological process under stress in kenaf. Finally, we showed that the levels of histone H3 and H4 acetylation were modulated by salt and drought stress in kenaf. CONCLUSIONS: We have isolated and characterized six HDACs genes from kenaf. These data showed that HDACs are imperative players for growth and development as well abiotic stress responses in kenaf.