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.

RNA editing analysis of ATP synthase genes in the cotton cytoplasmic male sterile line H276A

BACKGROUND: Pollen development is an energy-consuming process that particularly occurs during meiosis. Low levels of adenosine triphosphate (ATP) may cause cell death, resulting in CMS (cytoplasmic male sterility). DNA sequence differences in ATP synthase genes have been revealed between the N- and S-cytoplasms in the cotton CMS system. However, very few data are available at the RNA level. In this study, we compared five ATP synthase genes in the H276A, H276B and fertile F1 (H276A/H268) lines using RNA editing, RNA blotting and quantitative real time-PCR (qRT-PCR) to explore their contribution to CMS. A molecular marker for identifying male sterile cytoplasm (MSC) was also developed. RESULTS: RNA blotting revealed the absence of any novel orf for the ATP synthase gene sequence in the three lines. Forty-one RNA editing sites were identified in the coding sequences. RNA editing showed that proteins had 32.43% higher hydrophobicity and that 39.02% of RNA editing sites had proline converted to leucine. Two new stop codons were detected in atp6 and atp9 by RNA editing. Real-time qRT-PCR data showed that the atp1, atp6, atp8, and atp9 genes had substantially lower expression levels in H276A compared with those in H276B. By contrast, the expression levels of all five genes were increased in F1 (H276A/H268). Moreover, a molecular marker based on a 6-bp deletion upstream of atp8 in H276A was developed to identify male sterile cytoplasm (MSC) in cotton. CONCLUSIONS: Our data substantially contributes to the understanding of the function of ATP synthase genes in cotton CMS. Therefore, we suggest that ATP synthase genes might be an indirect cause of cotton CMS. Further research is needed to investigate the relationship among ATP synthase genes in cotton CMS.

Analysis of three wheat cytoplasmic male sterile lines mitochondrial DNA by AFLP / 生物工程学报

Cytoplasmic male sterility is an important way to utilize wheat heterosis. The purpose of thisstudy was to identify cytoplasmic type of three wheat male sterile lines. Amplified fragment length polymorphism (AFLP) marker technique was used to analyze the wheat mitochondrial DNA. We isolated mitochondria by differential centrifugation and density gradient ultracentrifugation. The results show that the extracted mitochondrial DNA was pure. It was suitable for PCR and genetic analysis. We got 4 pairs of specific primers from 64 primers combinations. Primer E1/M7 amplified 3 specific fragments in ms(Kots)-90-110. Primer E4/M2 generated 2 specific fragments in ms(Ven)-90-110. Primer E7/M6 amplified 2 specific fragments in ms(S)-90-110. Primer E6/M4 produced 2 specific fragments in ms(Kots)-90-110. Four specific primers could be used to identify three cytoplasmic types of Aegilops kotschyi, Ae. ventricosa and Triticum spelta. It provided the molecular basis to further study the mechanism of wheat cytoplasmic male sterility.

Tissue culture of Vinca minor and determination of vincamine / 中国中药杂志

<p><b>OBJECTIVE</b>To study tissue culture of Vinca minor and determine the content of vincamine.</p><p><b>METHOD</b>Leaf blades, stalks, root segment of V. minor were used as explants to study the effect of 2, 4-D,6-BA,NAA on its callus induction and vincamine contents in the orthogonal design experiment. In the peak period of callus formation, vincamine content in callus of V. minor and sterile plants was determined by HPLC. The experimental data was statistically analyzed.</p><p><b>RESULT</b>The content of 6-BA and NAA had no significant effect on its callus induction. But the content of 2, 4-D had significant effect on its callus induction. Within 20,40,60 d, the content of vincamine in sterile plant was (0.015 +/- 0.003)%, (0.097 +/- 0.001)% , (0.113 +/- 0.06)%, respectively. In the peak period of callus formation, vincamine content in callus of leaf blades, stalks, root segment was (0.024 +/- 0.0025)%, (0.016 +/- 0.0015)%, (0.010 +/- 0.0015)%, respectively. To 30 days of subculture, vincamine content in callus of leaf blades, stalks, root segment was (0.041 +/- 0.002)%, (0.019 +/- 0001)%, (0.016 +/- 0.002)%, respectively.</p><p><b>CONCLUSION</b>The optimal hormone combination for callus initiation was MS +2, 4-D 1.0 mg x L(-1) +6-BA 0.5 mg x L(-1) + NAA 0.5 mg x L(-1). In different growth periods, vincamine content in sterile plants is significantly different. From different explants in callus vincamine content is different, in which leaves callus is significantly higher than that of stems, roots produced callus organization.</p>

Characteristics and abortion cytological pathways of male sterility of Bupleurum chinense / 中国中药杂志

<p><b>OBJECTIVE</b>To study the characteristics of male sterility of Bupleurum chinense and further explore the developmental period and reason of abortion for the male sterile plants.</p><p><b>METHOD</b>The morphological characteristics of B. chinense male sterile and normal plants were investigated and compared. The anther development process and pollen viability of two types of plants were examined by microscopic assay.</p><p><b>RESULT AND CONCLUSION</b>The shapes and sizes of anther and filament were different between the male sterile and the normal plants. For the male sterile plant's, the filament size was no more than 1/2 of that of normal plants and the anthers were shriveled, failed to dehisce and pollinate naturally, and the pollen grains in the anthers had no vitality. Other morphological characteristics were similar between two types of plants. The main reason leading to male sterility of B. chinense was the abnormal development of tapetum cells with two circumstances. The one is that the tapetum cells degraded early during the period of microsporocyte phase to tetrad phase and the other is that the tapetum cells proliferated with delayed degradation in the tetrad to uninucleate phase.</p>

Pollen viability and stigma receptivity of Salvia miltiorrhiza and its relative / 中国中药杂志

<p><b>OBJECTIVE</b>To provide the basal data for artificial cross breeding of Chinese herb Salvia miltiorrhiza from 7 provinces in China and its 4 relatives.</p><p><b>METHOD</b>The pollen viability was evaluated by TTC (2, 3, 5-triphenylte trazolium chloride) test and the stigma receptivity was evaluated by benzidine-H2O2 method.</p><p><b>RESULT</b>The pollen viability of S. miltiorrhiza from 6 provinces in China and its 4 relatives deceased during time of pollen shedding. Their highest pollen viability was in 2 or 3 days after blooming. But the pollen viability of S. miltiorrhiza (wild and culture) from Hean province in China declined with time after blooming. The most obvious variation of the pollen viability was in S. miltiorrhiza from Shanxi province (RSD 71.3% ) and the least was in wild S. miltiorrhiza from Henan province (RSD 12.4%). The highest average pollen viability was wild S. miltiorrhiza (72.3%) from Henan province while the lowest was S. yunnanensis (38.8%). The stigmas of all the accessions had receptivity when blooming. The stigma receptivity of S. brevilabra was strong in 2 to 4 days after blooming, while the others had less change after blooming. The life span of pollen grains and stigmas could be maintained from 3 to 5 days.</p><p><b>CONCLUSION</b>The optimum artificial pollination time of S. miltiorrhiza and its relatives was 2 to 3 days after blooming.</p>

Study on pollen viability and stigma receptivity of 5 Iris plants / 中国中药杂志

<p><b>OBJECTIVE</b>To increase the reproduction efficiency of Iris plants.</p><p><b>METHOD</b>Pollen viability, stigmatic receptivity, the color of anther and stigma of 5 Iris plants were observed during blooming.</p><p><b>RESULT</b>1. The highest pollen viability was in 4 hours after blooming; 2. The stigmatic receptivities of I. sichuanensis, I. leptophylla, I. lactea and I. goniocarpa were strong in 4 hours after blooming, while that of I. lactea var. chinensis was strong in 2 hours after blooming; 3. The color of anther could reflect the pollen viability, but could not indicate the viability level; 4. The stigma color could not reflect the receptivity of stigma.</p><p><b>CONCLUSION</b>The optimum artificial pollination time of these five species were 12:00 -14:00.</p>

The pTA29-barnase chimeric gene transformation of Brassica campestris L. subsp. chinensis Makino var. parachinensis mediated by agrobacterium / 生物工程学报

In order to induce male sterility of Brassica campestris L. subsp. chinensis Makino var. parachinensis, we introduced the chimeric pTA29-barnase gene into it by Agrobacteriumtume faciens transformation. We obtained the transgenic plants, and determined them by PCR, Southern blotting and RT-PCR analysis. Results indicated that the RNase (barnase) gene had been transferred into genome of plant, and its expression level was different among transformation plants. All transgenic plants were male sterile; there was no vigor or a little pollen without fertility in the anther of transgenic plants. The transgenic plants failed to produce seeds under the condition self-control pollination, but hybrid seeds set were obtained when these transgenic plants were cross-pollinated artificially with normal pollen from untransformed plants. Progeny from cross-pollinated maintainer line with transgenic plants segregated in the 1:1 for male sterility and male fertility, and these phenotypes corresponded directly to the presence or absence of the chimeri TA29-barnase gene. The male fertile plants of co-separated progenies could die by spraying 10 mg/L PPT in cotyledon seedling stage. The hybrid F1 between male sterility and other varieties showed heterosis in yield and growth. All these show that it is an efficient method to induce male sterility in Brassica campestris L. subsp. chinensis Makino var. parachinensis by TA29-barnase ene, there is potential on heterosis breeding of Brassica campestris L. subsp. chinensis Makino var. parachinensis.

Reversible male sterility in transgenic tobacco carrying a dominant-negative mutated glutamine synthetase gene under the control of microspore-specific promoter.

Metabolic engineering was used to disrupt glutamine metabolism in microspores in order to block pollen development. We used a dominant-negative mutant (DNM) approach of cytosolic glutamine synthetase (GS1) gene under the microspore-specific promoter NTM19 to block glutamine synthesis in developing pollen grains. We observed partial male sterility in primary transgenic plants by using light microscopy, FDA, DAPI and in vitro pollen germination test. Microspores started to die in the early unicellular microspore stage, pollen viability in all primary transgenic lines ranged from 40-50%. All primary transgenics produced seeds like control plants, hence the inserted gene did not affect the sporophyte and was inherited through the female germline. We regenerated plants by in vitro microspore embryogenesis from 4 individual lines, pollen viability of progeny ranged from 12 to 20%, but some of them also showed 100% male sterility. After foliage spray with glutamine, 100% male-sterile plants were produced viable pollen and seed set was also observed. These results suggested that mutated GS1 activity on microspores had a significant effect on normal pollen development. Back-cross progenies (T2) of DH 100% male-sterile plants showed normal seed set like primary transgenics and control plants.

A duplicated coxI gene is associated with cytoplasmic male sterility in an alloplasmic Brassica juncea line derived from somatic hybridization with Diplotaxis catholica.

A cytoplasmic male sterile (CMS) line of Brassica juncea was derived by repeated backcrossing of the somatic hybrid (Diplotaxis catholica + B. juncea) to B. juncea. The new CMS line is comparable to euplasmic lines for almost all characters, except for flowers which bear slender, needle-like anthers with aborted pollen. Detailed Southern analysis revealed two copies of coxI gene in the CMS line. One copy, coxI-1 is similar to the coxI gene of B. juncea, whereas the second copy, coxI-2 is present in a novel rearranged region. Northern analysis with eight mitochondrial gene probes showed altered transcript pattern only for the coxI gene. Two transcripts of 2.0 and 2.4 kb, respectively, were detected in the CMS line. The novel 2.4 kb transcript was present in floral bud tissue but absent in the leaf tissue. In plants where male sterility broke down under high temperature during the later part of the growing season, the 2.4 kb coxI transcript was absent, which suggested its association with the CMS. The two coxI genes from the CMS line showed two amino acid changes in the coding region. The novel coxI gene showed unique repeats in the 5' region suggesting recombination of mitochondrial genomes of the two species. The possible role of the duplicated coxI gene in causing male sterility is discussed.

Homeotic-like modification of stamens to petals is associated with aberrant mitochondrial gene expression in cytoplasmic male sterile Ogura Brassica juncea.

We have previously reported correction of severe leaf chlorosis in the cytoplasmic male sterile Ogura (also called Ogu) Brassica juncea line carrying Ogura cytoplasm by plastid substitution via protoplast fusion. Two cybrids obtained from the fusion experiment, Og1 and Og2, were green and carried the plastid genome of B. juncea cv. RLM198. While Og1 displayed normal flower morphology comparable to that of its euplasmic B. juncea counterpart except for sterile anthers, Og2 retained homeotic-like floral modification of stamens to petal-like structures and several other floral deformities observed in the chlorotic (Ogu) B. juncea cv. RLM198 (or OgRLM). With respect to the mitochondrial genome, Og1 showed 81% genetic similarity to the fertile cultivar RLM while Og2 showed 93% similarity to OgRLM. In spite of recombination and rearrangements in the mitochondrial genomes in the cybrids, expression patterns of 10 out of 11 mitochondrial genes were similar in all the three CMS lines; the only exception was atp6, whose expression was altered. While Og1 showed normal atp6 transcript similar to that in RLM, in Og2 and OgRLM weak expression of a longer transcript was detected. These results suggest that the homeotic-like changes in floral patterning leading to petaloid stamens in Og2 and OgRLM may be associated with aberrant mitochondrial gene expression.

Gene cloning and expression analysis of a male sterility related gene BoDHAR from broccoli / 生物工程学报

A differentially expressed cDNA fragment obtained from a cDNA-AFLP analysis, which performed on floral buds of male sterile and fertile lines of cabbage, was used as a querying probe to blast the Genbank and Arabidopsis databases. Based on the assembled homologous cDNA sequences, a full-length cDNA of 633 bp for BoDHAR was cloned by RT-PCR. Furthermore, we have experimentally cloned and sequenced the 5' flanking sequence of gene BoDHAR by genomic walking method based on ligation-mediated PCR. The full length DNA sequence with 1486bp, containing two introns, was achieved. Homologous analysis shows that gene has 82.3% identity at nucleotide level, and 79.6% identity at amino acid level with Arabidopsis dehydroascorbate reductase (DHAR) gene AT1 G19570.1. Structurally, BoDHAR encodes a polypeptide of 210 amino acids, which contains a GST-c-DHAR domain highly conserved among other members of the DHAR superfamily and has multiple phosphorylation sites. Promoter predictions software indicated that the 5' upstream region contained putative transcription signals and conserved sequences, one CAAT-box, one G-box and four TGAC-like motifs. To advance our understanding of gene BoDHAR, tissue expression pattern were analyzed by semi-quantitative RT-PCR. The results indicate that expression level of gene BoDHAR is higher in fertile buds than that in sterile buds, and expressed intensively in the anther.

Using single primer PCR to amplify the orf25 gene fragment related to plant male-sterility in Salicornia europaea / 生物工程学报

The gene orf25 encodes functional protein that may play an important role in plant fertility control in nature. To clone the orf25 from Salicornia europaea Xinjiang into a T-vector, a single designed primer was used to amplify 1.7kb cDNA fragment with RT-PCR. Sequence analysis reveals that the cloned fragment contains entire orf25 coding region with 98%, 95%, 92% and 88% identity to that of orf25 from Beta vulgaris, Nicotiana, wheat and maize mitochondrion, respectively. This analysis suggests that orf25 gene is highly conserved in terms of evolution in plant; and it also suggests that wild plant Salicornia europaea contain a male-sterility gene similar to crops that is of great importance in improvement of the breed of crop.