Characterization of Fertility Alteration in 8 Environment-sensitive Genic Male-sterile Lines of indica Rice

Eight indica ( Oryza sativa L.) environment-sensitive genic male-sterile (EGMS) lines, 2-2S, K1405S, F131S, 2136S, Pei-Ai 64S, 1290S, GD-IS and N17S, were sequentially seeded with 10-15 d interval at three sites, Wuhan in 1997, Guiyang in 1997 and Sanya in 1997 and 1998, China. The results of investigations on self-sterilities showed that all of eight EGMS lines had stable sterile periods of longer than 30 d at Wuhan. They can be used for seed production of two-line hybrid rice, but can not reproduce themselves. Their stable sterile periods were shorter than 30 d at Guiyang, they can reproduce themselves and can not be used for hybrid seed production. In Sanya, their stable sterile periods were longer than 150 d, all of eight lines can be used for seed production in summer and autumn and reproduce themselves in winter. The fertility of all eight lines were sensitive to temperature. The sensitive stages, sensitive duration and critical point of temperatures (CPT) of fertility alteration in various lines were different. The sensitive stages of 2-2S and K1405S were from 18 d to 9 d before heading, the sensitive durations were 7-10 d and the CPTs were 23.7-24.5 degreesC. The sensitive stage, sensitive duration and CPT of F131S were from 17 to 5 d before heading, 13 d and 24.3-24.7 degreesC, respectively. The sensitive stage, sensitive duration and CPT of 2136S were from 18 to 12 d before heading, 7 d and 24.6-25.1 degreesC:, respectively. The sensitive stages, sensitive durations of Pei-Ai 64S, 1290S, N17S and GD-1S were from 24 to 13 d before heading and 10-13 d. And their CPTs were 24.6-25.1 degreesC, 25.5-26.2 degreesC, 25.4-26.1 degreesC,, and 24.1-24.7 degreesC, respectively.

Study on High-Eefficient Breeding Technology Platform of Dwarf Male-Sterile Wheat

[Purpose] The paper is to discuss the high-efficient breeding technology platform of dwarf male-sterile wheat.[Method] Conclusion was made upon the development of the creation and application of dwarf male-sterile wheat,and the conception of introducing haploid breeding technology into the technological system of high-efficient breeding of dwarf male-sterile wheat was proposed.[Result] Dwarf male-sterile wheat not only retains the properties of total male abortion of Taigu Genetic Sterile Wheat,steady sterility,and high hybrid rate after open pollination,but also has the characteristic of high dwarfing ability of Aibian No.1,becoming a comparatively ideal population modification means.At present,the application of dwarf male-sterile wheat mainly includes germplasm resources platform of population modification by using dwarf male-sterile wheat,technology platform of constructing new high-efficient breeding system by using dwarf male-sterile wheat,and production platform of using dwarf male-sterile wheat to breed new varieties.Through the introduction of haploid breeding into the already established wheat high-efficient breeding system,a new system of high-efficient biological breeding technology of dwarf male-sterile wheat was constructed theoretically.[Conclusion] The study provides references to the further study and application of dwarf male-sterile wheat.

Electron-Microscopic Study of Microsporogencsis in Male-sterile and Male-fertile Grain Amaranth(Amaranthus hypochondriacus L.)

A comparative study of microsporogenesis in male-sterile and male-fertile grain amaranth was conducted using electron-microscopy.The onset of microsporogenesis breakdown in male-sterile is at the mononuclear pollen stage following the release of microspores from tetrads.Abnormality in the behavior of degenerated tapetum was observed, which failed to envelope individual microspores after their release, leading to an abnormal vacuolation in the mononuclear pollen grains.As a result, the normal thickening of pollen wall could not occur and pollen grains could not engorge, causing male sterility.

Brassinosteroids mediate the effect of high temperature during anthesis on the pistil activity of photo-thermosensitive genetic male-sterile rice lines

Brassinosteroids(BRs)play critical roles in a wide range of plant developmental processes.However,it is unknown whether and how BRs mediate the effect of high temperature(HT)stress during anthesis on the pistil activity of photo-thermosensitive genetic male-sterile(PTSGMS)rice(Oryza sativa L.)lines.This study investigated the question.Three pot-grown PTSGMS rice lines were subjected to HT stress during anthesis.The contents of 24-epibrassinolide(24-EBL)and 28-homobrassinolide(28-HBL),the major forms of BR in rice plants,and levels of reactive oxygen species(ROS)or antioxidants(AOS),hydrogen peroxide(H2O2),1-aminocylopropane-1-carboxylic acid(ACC),ascorbic acid(AsA),and catalase activity in pistils,were determined.HT stress significantly reduced the contents of both 24-EBL and 28-EBL relative to those under normal temperatures,but the reduction varied by PTSGMS line.A line with higher BR contents under HT stress showed lower contents of ACC and H2O2,higher catalase activity and AsA content in pistils,and higher fertilization rate,seed-setting rate,and seed yield when the line was crossed with a restorer line,indicating that higher levels of BRs increase HT stress resistance.Applying 24-EBL,28-HBL or an inhibitor of BR biosynthesis confirmed the roles of BRs in response to HT stress.The results suggest that BRs mediate the effect of HT stress on pistil activity during anthesis and alleviate the harm of HT stress by increasing AOS and suppressing ROS generation.

Genetic Analysis and Preliminary Mapping of a Highly Male-Sterile Gene in Foxtail Millet(Setaria italica L.Beauv.) Using SSR Markers

Breeding of male-sterile lines has become the mainstream for the heterosis utilization in foxtail millet,but the genetic basis of most male-sterile lines used for the hybrid is still an area to be elucidated.In this study,a highly male-sterile line Gao146A was investigated.Genetic analysis indicated that the highly male-sterile phenotype was controlled by a single recessive gene a single recessive gene.Using F 2 population derived from cross Gao146A/K103,one gene controlling the highly male- sterility,tentatively named as ms1,which linked to SSR marker b234 with genetic distance of 16.7 cM,was mapped on the chromosome VI.These results not only laid the foundation for fine mapping of this highly male-sterile gene,but also helped to accelerate the improvement of highly male-sterile lines by using molecular marker assisted breeding method.

Differences in Nuclear DNA Between Male-Sterile and Male-Fertile Lines of Sorghum bicolor

Cytoplasmic male sterility(cms)is determined by nuclear-cytoplasmic interactions. Up to now, most studies are focused on the comparison of cytoplasmic DNAs of male-sterile lines and male-fertile lines, and analysis of nuclear DNA has not been documented yet. In order to find out the possible difference in nuclear genome of male-sterile line A1 Tx623 and corresponding male-fertile line Tx623 of sorghum, random amplified polymorphic DNA(RAPD)approach was used to analyze their cytoplasmic and nuclear genomes. Total DNAs of them were amplified at first to screen primers, which were able to generate reproducible bands specific to male-sterile line or male-fertile line. Then the selected primers were used to amplify their mitochon-drial DNA(mtDNA)and chloroplast DNA(cpDNA). The origins of all the polymorphic fragments were analyzed. After ruling out those amplified from cytoplasmic DNA, seventeen polymorphic fragments were determined to be amplified from nuclear DNA. These fragments originated from nuclear DNA indicate that differences in sequence exist between the nuclear DNA of male-sterile line and male-fertile line of sorghum, which do not agree with the traditional standpoint that they have identical nucleus.

Utilization of recessive male-sterile lines in soybean

Three male-sterile soybean (MS) groups were selected out through various methods. A number of filial generations and hybrid strains with special characters were obtained by the methods of isolated plot and backcross. Among them Jinping 1 and Jinping 2, two sister lines,with higher production,big and pretty seed,green coat and a rich perfume,are suitable to a vegetable in city. It was proved that the MS have wide utilization potential as follows; (a)the MS could solve a lot of troubles of artificial cross ;for instance,the green seed coat can be used as a gene marker; (b)the MS showed a high hybrid vigor and its potential ratio ranged from 132% to 347% ;and (c)the effects of recurrent selection of MS were obvious and the characters of yield of F5 in 18 strains were higher than that of F3.

Studies on the Recross Heterosis Effect of Male-sterile Single-hybrids in Corn

Re-cross was conducted between five ES cytoplasm male-sterile hybrids and four high-oil hybrids, and five normal hybrids, respectively. The oil content, yield, 1000-kernel weight and kernel size were estimated. Results were as follows: The average kernel oil content in the male-sterile hybrid ×high-oil hybrid was 1.6% higher than that of the female parent. The xenia effect value of oil genes was 0.30. The yield and 1000-kernel weight of male-sterile hybrids were 10.1% and 5.8% higher than that of corresponding fertile hybrids respectively, which showed significant cytoplasm effect. The yield of the male-sterile hybrid × high-oil hybrid was similar to that of the female parent, but its 1000-kernel weight was 7.3% lower than that of the female parent. Compared with the high-oil male parent, grain yield, 1000-kernel weight and kernel size of the male-sterile hybrid× high-oil hybrid were higher. Seed-filling rate, the days of seed-filling and IAA content in the male-sterile hybrid × high-oil hybrid showed average heterosis tending the female parent, which may be perhaps one of the reasons resulting in the average heterosis tending to the female parent on kernel oil content, yield, 1000-kernel weight and kernel size.

Analysis of a Partial Male-Sterile Mutant of Arabidopsis thaliana Isolated from a Low-Energy Argon Ion Beam Mutagenized Pool

A screen for Arabidopsis fertility mutants, mutagenized by low-energy argon ion beam, yielded two partial male-sterile mutants tc243-1 and tc243-2 which have similar phenotypes. tc243-2 was investigated in detail. The segregation ratio of the mutant phenotypes in the M2 pools suggested that mutation behaved as single Mendelian recessive mutations, tc243 showed a series of mutant phenotypes, among which partial male-sterile was its striking mutant characteristic. Phenotype analysis indicates that there are four factors leading to male sterility, a. Floral organs normally develop inside the closed bud, but the anther filaments do not elongate sufficiently to position the locules above the stigma at anthesis, b. The anther locules do not dehisce at the time of flower opening （although limited dehiscence occurs later）, c. Pollens of mutant plants develop into several types of pollens at the trinucleated stage. as determined by staining with DAPI （4＇,6-diamidino-2-phenylindole）. which shows a variable size. shape and number of nucleus. d. The viability of pollens is lower than that of the wild type on the germination test in vivo and vitro.

Development of Maweizhan cytoplasmic male-sterile line in rice(Oryza sativa L.)

A male sterile mutant plant was found from the rice field of the local rice variety which was cultivated for a long time in the west of Hubei Province. The plant has more vigorous tillering ability. Its plant height of 95 cm was a bit shorter than that of the normal ones. The plant type, the leaf shape and the color of leaf sheath and glume tip of this mutant were identieal to that of the normal plant whereas the color of arrowhead-shape anther was milky white. This mutant set no seed during self-pollination. When it was crossed with IR24. IR26, Minhui 63 or Xieqing-zaoxuian. the Ffertilities were normal. The fertility of this mutant could be restored by IR24, IR26 and Minhui 63 and maintained by Xieqing-zaoxian. Maxie A was developed in 1987 by the successive backcrossing of the mutant with Xieqing-zaoxian. The percentage of abortive pollen in Maxie A in uninucleate microspore to early binucleate microspore stage is

Relationship between rice heading sensitivity and male-sterile sensitivity to photoperiod in view of developmental genetics

We studied the relationship between the head-ing sensitivity and the male-sterile sensitivityin photoperiod-sensitive genie males-sterile rice(PGMSR)and conventional rice.Materialsused in this study were 7001S,a late maturingPGMS japonica strain derived from Nongken58S; Akihikari and Youmang-zaojing(YMZJ),two early maturing conventional Japonica rice;and CPSLO-17,a Wide compatible convention-al indica rice.The heading date and seed-set-ting rate of Fand Fof three cross combina-tions between PGMSR and conventional riceswere examined in phytotron which was adjust-ed at 25±1℃ with day-length of 14.5 h(LD)and 12 h(SD).The segregation ratio of fertile:sterile in Funder LD was in accordance

Effect of day length and temperature on the pollen fertility in photo(thermo)-sensitive genic male-sterile rice

The effect of day length and temperature on the pollen fertility of five photoperiod-sensitive genic male-sterile japonica rice lines (PGMSR) and three temperature-sensitive genic malesterile indica rice lines (TGMSR) were investigated in phytotron. The light source used for illumination was xenon lamp, and the light intensity which plant accepted on the leaf surface was 300—350μmol photons ms. The results indicated that pollens of PGMSR 7001S and E47S aborted completely whereas a little part of 31116S pollens appeared normal under long day photoperiod (LD,25℃,15h) (Table 1). High temperature (HT, 30℃, 12h) and lower temperature (LT,

Chromosome Location of the Male-sterility and Yellow Seedling Gene in Line 1066A of Foxtail Millet

Using foxtail millet (Setaria italica (L.) Beauv.) male-sterile line 1066A as female parent and Yugu 1 primary trisomic series (1 - 7) and tetrasomics 8, 9 as male parents, chromosome location of gene for male-sterility and yellow seedling in line 1066A was studied by primary trisomic analysis. The plants of F-1 generation of trisomics 2 - 9 were obtained by crossing with a great many plants of 1066A. F-1 generation of trisomics was similar to their male parent in morphologic characters, the color of their seedling was green, and pollen was partially fertile. The segregation ratio of fertility to sterility is 3:1 in F-2 generation of trisomics 2, 3, 4, 5, 7, 8 and 9; and 14:1 only in F-2 generation of trisomic 6 (chi(0.05)(2) = 0.012). The segregation ratio of green seedling to yellow seedling is 12:1 only in F-2 generation of trisomic 7 (chi(0.05)(2) = 0.31), but in other cases, this ratio is 3:1. The results indicated that the male-sterility gene was located on chromosome 6, and the gene for yellow seedling was monogenic recessive and located on chromosome 7. The rate of trisomics transmission by pollen was tested, trisomics 8 and 9 were the highest in rates of trisomics transmission and followed by trisomics 6 and 4.

Application of hybrids with cytoplasmic male-sterility in Zea mays L.in China

The abortive behaviour and the cytoplasm quality of cytoplasmic male-sterility(CMS)lines of homocaryon were investigated and the existence of C race of Bipolaris maydiswere discussed from the point of view of genetic breeding,physiology and pathology in this paper.Then the countermeasures to prevent the danger from disease of B. maydis in CMS hybrid pro-duction were proposed.

Generation of thermosensitive male-sterile maize by targeted knockout of the ZmTMS5 gene

Maize（Zea mays L.）is one of the most important cereal crops,with a global production of 1.02 billion tons in 2013（Baldaufa et al.,2016）.Heterosis is widely used to increase the productivity of maize,and the first commercial hybrid maize was introduced in the 1930s（Duvick,2001）.

Analysis of Male Sterility-Related Proteins of Young Panicle in Rice (Oryza sativa L.) by Two-Dimensional Electrophoresis

For searching out male sterility-related proteins (polypeptides) in rice(Oryza sativa L. ), we examined the difference of panicle protein (polypeptides) between hybrid rice( Wujin2A/R168, Wujin5A/R988) and their parents (male-sterile line Wujin2A, Wujin5A, and restorerline R168, R988) at the formation stage of pollen mother cell by two-dimensional electrophoresis(2-DE). The results revealed that the 2-DE polypeptide maps were similar among these experimentalmaterials. A small group of polypeptides were disappeared in 2-DE polypeptide maps of male-sterileline (Wu-jin2A, WujinSA) by comparing to restorer line (R168, R988) and the first filial (F, )generation (Wujin2A/R168, Wujin5A/R988). The isoelectric points of these polypeptides were pl5.8-6.5, molecular weight 42. 7 X 10~3-66. 2 X 10~3.

Molecular tagging of a genic male-sterile gene in rice

The sterility of Pingxiang male-sterile rice (Pins), possibly derided from a spontaneous mutation in Pingxiang fertile rice (Pmf), was previously reported to be controlled by a single dominant nuclear gene. It can be restored to fertility either by a dominant epistatic gene or by higher temperature treatment at the early stage of inflorescence development. In order to tag the genie male-sterile gene, Pms, Pmf and Ce 64, a cytoplasmic male-sterile restoring line without the epistatic gene for Pms, were used to construct mapping populations. Two segregation populations, "(Pms/Ce 64) F1s (sterile plant)//Pmf" F1 and "Pms//(Pmf/Ce 64) F1" F1, were simultaneously developed. Subsequently, the genie male- sterile gene was mapped between a simple sequence length polymorphism marker, RM228, and a restriction fragment length polymorphism marker, G2155, with distances of 14.9 and 2.6 cM, respectively. The tagged dominant genie male-sterile gene is temporarily designated Ms-p.

Effectiveness of population improvement through recurrent selection for scab resistance in wheat using dominant male-sterile gene ms2

An original base population with wide genetic variability was developed by multiple-parent cross- ing,intermating and recrossing using the dominant male-sterile gene ms2(Tal).Then the phenotypic recurrent selection was conducted for the male-sterile plants in order to improve the population and develop a gene pool with increased resistance to scab in wheat.Generations RC_0-RC_2 and RC_1-RC_5 from the resistance resource pool were evaluated for the resistance and the effect of population improvement was analyzed in Nanjing under soil-surface inoculation with F.graminearum-diseased seeds in 1988/1989 and single-floret inoculation with ascospore suspension of G.zeae in 1991/1992,respectively.The experimental results of the soil-surface inoculation indicated that the numbers or percentages of diseased spikelets and seeds per spike of the male-fertile plants were decreased significantly and the comprehensive resistance of the population to scab was obviously increased.The percentages of uninfected seeds per spike in generations RC_0,RC_1 and RC_2 were 49.2%,65.5% and 70.7%,respectively.The frequencies of plants with lower than 30% of diseased spikelet and seed percentages in the population were increased by 40% and 36%,respectively,through 2 cycles of se- lection.Under the condition of the single-floret inoculation,the results further demonstrated that the resistance to the fungal spread could be improved significantly through the phenotypic recurrent selection.The opportunity of obtaining superior resistant plants from the population would be enhanced gradually with the development of the gene pool.On average,from RC_1 to RC_5,the population mean of diseased spikelets of inoculated spikes was reduced by 8.6% and the frequency of resistant plants with fewer than 4 diseased spikelets per inoculated spike was increased by 4.2%,respectively,per cycle.The frequency of susceptible plants with more than 10 diseased spikelets in inoculated spikes was decreased by 9.2% after 4 cycles of se- lection.The genetic variance for resistance reduced remarkably but no significant decrease in the genetic coefficient of variation was found during the first 4 cycles of selection.

Maize Genic Male-Sterility Genes and Their Applications in Hybrid Breeding: Progress and Perspectives

As one of the most important crops, maize not only has been a source of the food, feed, and industrial feedstock for biofuel and bioproducts, but also became a model plant system for addressing fundamental questions in genetics. Male sterility is a very useful trait for hybrid vigor utilization and hybrid seed production. The identification and characterization of genic male-sterility (GMS) genes in maize and other plants have deepened our understanding of the molecular mechanisms controlling anther and pollen development, and enabled the development and efficient use of many biotechnology-based male-sterility (BMS) systems for crop hybrid breeding. In this review, we summarize main advances on the identification and characterization of GMS genes in maize, and con struct a putative regulatory network controlling maize anther and pollen development by comparative genomic analysis of GMS genes in maize, Arabidopsis, and rice. Furthermore, we discuss and appraise the features of more than a dozen BMS systems for propagating male-sterile lines and producing hybrid seeds in maize and other plants. Finally, we provide our perspectives on the studies of GMS genes and the development of novel BMS systems in maize and other plants. The continuous exploration of GMS genes and BMS systems will enhance our understanding of molecular regulatory networks controlling male fertility and greatly facilitate hybrid vigor utilization in breeding and field production of maize and other crops.

Premature Tapetum Degeneration: a Major Cause of Abortive Pollen Development in Photoperiod Sensitive Genic Male Sterility in Rice

Photoperiod-sensitive genic male-sterile （PSGMS） rice （Oryza sativa L.）, a natural mutant found in the rice cultivar Nongken 58, is very useful for the development of hybrid rice cultivars. Despite its widespread use in breeding programs, the initial stage of the abortive development of PSGMS rice and the possible cytological mechanisms of pollen abortion have not been determined. In the present study, a systematic cytological comparison of the anther development of PSGMS rice with its normal fertile counterpart is conducted. The results show that pollen abortion in PSGMS rice first occurs before the pollen mother cell （PMC） stage, and continues during the entire process of pollen development until pollen degradation. The abortive process was closely associated with the abnormal behavior of the tapetum. Although tapetum degeneration in PSGMS rice initiates already at the PMC stage, it proceeds slowly and does not complete until the breakdown of the pollen. Such cytological observations were supported by the results of the TUNEL （TdT-mediated dUTP Nick End Labeling） assay, which detects DNA fragmentation resulting from programmed cell death （PCD）, indicating that the premature tapetum degeneration is in the process of PCD.