Morphological and cytological assessments reveal pollen degradation causes pollen abortion in cotton cytoplasmic male sterility lines

Background Understanding the mechanism of male sterility is crucial for producing hybrid seeds and developing sterile germplasm resources.However,only a few cytoplasmic male sterility(CMS)lines of cotton have been produced due to several challenges,like inadequate variation of agronomic traits,incomplete sterility,weak resilience of restorer lines,and difficulty in combining strong dominance.Therefore,the morphological and cytological identification of CMS in cotton will facilitate hybrid breeding.Results Two F_(2) segregating populations of cotton were constructed from cytoplasmic male sterile lines(HaA and 01A,maternal)and restorer lines(HaR and 26R,paternal).Genetic analysis of these populations revealed a segregation ratio of 3:1 for fertile to sterile plants.Phenotypic analysis indicated no significant differences in traits of flower bud development between sterile and fertile plants.However,sterile plants exhibited smaller floral organs,shortened filament lengths,and anther atrophy on the flowering day in comparison with the fertile plants.When performed scanning electron microscopy(SEM),the two F_(2) populations revealed morphological variations in the anther epidermis.Cellular analysis showed no significant differences in pollen development before pollen maturation.Interestingly,between the pollen maturation and flowering stages,the tapetum layer of sterile plants degenerated prematurely,resulting in abnormal pollen grains and gradual pollen degradation.Conclusion The results of this study suggest that fertility-restoring genes are controlled by a single dominant gene.Sterile plants exhibit distinctive floral morphology,which is characterized by stamen atrophy and abnormal anthers.Pollen abortion occurs between pollen maturity and flowering,indicating that premature tapetum degradation may be the primary cause of pollen abortion.Overall,our study provides a theoretical basis for utilizing CMS in hybrid breeding and in-depth investigation of the dominant configuration of cotton hybrid combinations,mechanisms of sterility,and the role of sterile and restorer genes.

Study on the Agroclimatic Division of Thermosensitive Genetic Male Sterility Rice Breeding

Using the meteorological data and geographical information during January-March（1961-2010） accumulated by 18 stations of Hainan,a suitability zoning map for thermo-sensitive genetic male sterility（TGMS） rice was made by GIS technology based on temperature indicators required by TGMS rice during fertility sensitive period and heading-flowering period,aiming to provide reasonable layout and scientific basis for sustainable development of TGMS rice in Hainan Island under the background of global warming.The results indicated that the suitable planting zones covered the south regions of Wuzhishan,Jianfengling and Diaoluoshan;subordinate suitable zones expanded northward to central parts of Wuzhishan,Dongfang,Changjiang,Qiongzhong and southern parts of Wanning;the other regions were unsuitable for breeding.

Genetic Study on Barley Male Sterility

[Objective] The aim was to research the genetic mechanism of barley male sterility, and provide the theoretical reference for breeding strong heterosis hybrid of barley. [ Method] Fertility segregation phenomenon, morphological characteristics and main agronomic characters of male sterility character of 4 kinds of barley male sterility materials 2001 - 17, 2001 - 37, 2001 - 84 and 2001 - 116 and their dedved lines were observed and researched.[ Result] Barley male sterility existed genetic phenomenon of single dominant nuclear gene caused by environmental stimulation, its sterility controlled by MS, the sterile genotype was MSms. There was stable nucleo-cytoplasmic inheritance on barley male sterility which was controlled by cytoplasmic mate sterile gene S and nuclear gene rr, and its genotype was S（rr）, this male sterility belonged to CMS type sterility. Temperature had no effect on fertility. [ Conclusion] There was stable nucleo-cytoplasmic inheritance on barley male sterility, this result played a positively promoting role in barley practical production.

Creation and Genetic Analysis of a Male Sterility Mutant in Panicum miliaceum

Heterosis plays an important role in the development of new crop varieties with high-yielding, good-quality and biotic/abiotic stresses while male sterile line de- velopment is the key step to determine the success of heterosis utilization. A male sterile mutant, M207A was created in proso millet （Panicum mi/iaceurn, 2n=4x=36） for the first time using 60Co-y ray mutagenesis. Fertility identification and genetic analysis were carried out to characterize the mutant for its possible use for hetero- sis utilization in proso millet. First the sterility was investigated using both field sur- vey and indoor pollen microscopy identification. Then Pollinated by normal fertile proso millet cultivars, F1 and F2 populations from the mutant were obtained. Mean- while primary genetic analysis was also conducted using above populations in dif- ferent experimental sites, seasons and years. The results showed that the male sterile plant exhibited closed glumes, browning and dry anthers with few normal pollens. The sterility was stable and sterility rate was above 95% on average. The segregation ratio of fertile to sterile plants was 35：1 in the fertile selfing F2 popula- tion indicating that the mutant was a genic male sterility belonging to a pollen-less type controlled by a single recessive gene. The creation of the mutant, M207A can play a key role for heterosis utilization in proso millet.

Genetic Analysis and Primary Mapping of pms4, a Photoperiod-Sensitive Genic Male Sterility Gene in Rice (Oryza sativa)

To understand the genetic characteristics of a new photoperiod-sensitive genic male sterile line Mian 9S, some reciprocal crosses were made between Mian 9S and six indica rice materials, Yangdao 6, Luhui 602, Shuihui 527, Mianhui 725, Fuhui 838 and Yixiang 1B. Genetic analysis results suggested that the photoperiod-sensitive genic male sterility （PGMS） of Mian 9S was controlled by a single recessive nuclear gene. Thus, the F2 population derived from the cross of Yangdao 6/Mian 9S was used to map the PGMS gene in Mian 9S. By using SSR markers, the PGMS gene of Mian 9S was mapped on one side of the markers, RM6659 and RM1305, on rice chromosome 4, with the genetic distances of 3.0 cM and 3.5 cM, respectively. The gene was a novel PGMS gene and designated tentatively as pms4. In addition, the application of the pms4 gene was discussed.

Genetic analysis of fertility restoring genes for AL-type male sterility in wheat

In order to screen molecular markers linked to fertility restoring genes and further improve the breeding efficiency of restorer lines, in this study, wheat varieties 18A, 18B and 99AR144-1 were used as experimental materials to establish F2 fertility-segregating population. Plant quantitative trait ＂major gene ＋ polygene mixed mo- del＂ separation analysis method and simple sequence repeat （SSR） molecular markers were adopted for genetic analysis of four generations, including the parents （P~ and P2）, and hybrid （G and G） populations. The results show that AL-type fertility restoring gene is controlled by two pairs of additive-dominant-epistatic genes and addi- tive-dominant polygene; two primers linked to fertility restoring genes were selected by SSR molecular markers, including Xgwm95 on chromosome 2A and Barc61 on chromosome 1B, with the linkage distance of 15.0 cM and 18.0 cM, respectively. Based on verification, these two markers are reliable for distinguishing AL-type wheat ste- rile lines and restorer lines.

A Review on Creating Male Sterility in Vegetable Crops by Genetic Engineering

With the deep researches on male sterility genetic engineering of plants, several strategies creating male sterile materials have been developed, such as causing pollen abortion by cytotoxic genes, antisense RNA or RNAi silencing the expression of genes related to pollen development, early degradation of tapetum callose leading to male sterility. Male sterile transgenic plants can be obtained through genetic transformation with related genes destroying or interfering with pollen or anther development. Male sterile cauliflower, tomato, cabbage, etc. have been developed in this way, and some begin to be used to produce hybrid seed. Appling some techniques can also maintain and restore the male sterility. These related researches will effectively promote the heterosis utilization and the development of crop breeding. This paper mainly presents their principles and applications in vegetable crops.

Genetic analysis of fertility restoration of Maxie cytoplasmic male sterility in rice(Oryza sativa L.)

The genetic behavior of fertility restorationgenes of the cytoplasmic male sterile line Max-ie A was studied to facilitate the use ofMaweizhan male sterile cytoplasm.The F,F,and Fof Maxie A/Minhui 63 were grownin paddy field,1993-1995.Meanwhile,someof the Fplants were testcrossed with themaintainer of Maxie A.The fertilities were

Genetics of Fertility Restoration in Cytoplasmic Male Sterile Pepper

Pepper hybrid seeds production using male sterility could lower cost by reducing time and labour, and increase the genetic purity of the F1 seeds. To investigate the genetics of fertility restoration of the Peterson cytoplasmic sterility in pepper, a doubled haploid population of 115 pepper lines obtained from anther culture of the F1 hybrid between Yolo Wonder （sterility maintainer line） and Perennial （fertility restorer line） and the parental lines were test-crossed by 77013A （a strict cytoplasmic-genic male sterile line）. The fertility of the test-crossed lines was assessed in greenhouse and open field with the following three criteria： pollen index （PI, visual estimation of pollen amount per flower）, pollen number （PN, pollen counting under microscope）, and seed number （SN, the number of seeds per fruit in open pollination）. Correlations between the each couple of criteria within, as well as between the cultivation methods ranged from 0.55 to 0.84. Analysis of variance showed that the genotype （DH line） and environment were the significant sources of variation of the fertility. Narrow sense of heritance of fertility restoration ranged from 0.38 to 0.92, depending on the criteria and environment. The distribution of the progeny was continuous between the parental genotypes indicating the quantitative inheritance of fertility restoration. Inferred from segregation according to Snape et al.（1984）, the number of segregating genes was estimated to be that three to four genetic factors were involved in pollen traits （PI and PN） and five to eight genetic factors in seed production （SN）. The heredity analysis of the CMS will be helpful for understanding of the genetic mechanism of the fertility restoration and the exploitation of the CMS in hybrid seed production.

Comparisons on Genetic Diversity among the Isonuclear-Alloplasmic Male Sterile Lines and Their Maintainer Lines in Rice

Four sets of rice isonuclear-alloplasmic lines including 16 male sterile lines and their maintainer lines were analyzed by using 91 pairs of SSR primers to study the genetic diversity of nuclear genome and their relative relationships. A total of 169 alleles were detected in the 16 lines, with a frequency of polymorphic loci of 53.85% and an average number of alleles per locus of 1.8, and the average gene diversity was 0.228. Four sets of the isonuclear-alloplasmic male sterile lines shared 146 identical alleles, corresponding to 86.39% of the total alleles; meanwhile, there are 23 different alleles among the tested materials, being 13.61% of the total alleles. On average, 78.70% identical alleles and 21.30% different alleles of the total alleles were detected between the isonuclear-alloplasmic male sterile lines and their maintainer lines. There were 53.85% identical alleles and 46.15% different alleles of the total alleles among the homozygous allonucleus male sterile lines. The fingerprints were established for some male sterile lines and maintainer lines. All the materials tested were divided into three groups at the 0.2 genetic distance based on the cluster analysis. Eight lines of Huanong A and Huayu A （including Huanong B and Huayu B） were in the first group, four lines of Kezhen A （including Kezhen B） in the second group, and four lines of Zhenshan 97A （including Zhenshan 97B） in the third group. For the isonuclear-alloplasmic male sterile lines, the similarity coefficient between Y （Yegong） type and WA （wild abortive） type or between CW （Raoping wild rice） and WA type reached 87-98%.

Genetic Mechanism of Dominant Earliness in Kefeng A,a New Rice Cytoplasmic Male Sterile Line

Kefeng A is an early maturing indica cytoplasmic male sterile （CMS） line of rice. Combinations derived from Kefeng A and late maturing indica restorer lines showed dominant earliness to various extents. To understand the genetic basis of dominant earliness, the genotype of photoperiod-sensitive genes in Kefeng A was analyzed using a complete set of heading time near isogenic lines （NILs） EGO to EG7, ER, LR, T65, T65E^b, T65E^bm, T65m, NIL（Hd1） and NIL（Hd4）. Results indicated that Kefeng A contained two dominant photoperiod-sensitive alleles E1 and Se-1^U on E1 and Se-1 loci, respectively, and the genotype of photoperiod-sensitivity genes for heading time in Kefeng A was E1E1e2e2E3E3Se-1^USe-1UEf-1Ef-1. Based on the detected heading time genotype, in combination with the heading time of Kefeng A and the early maturing phenomenon in its derived F1 hybrids, it is speculated that Kefeng A might carry a dominant inhibitor gene Su-E7 for the dominant photoperiod- sensitive gene E1, and a recessive inhibitor gene i-Se-1 for another dominant photoperiod-sensitive gene Se-1. The reason why F1 hybrids from Kefeng A exhibited early maturing was hereby analyzed and the breeding value of dominant earliness related genes in Kefeng A was discussed.

Preliminary Study on Inheritance of Stigma Exertion in Wheat Thermo-photo Sensitive Genic Male Sterile Line

Stigma exertion is one of the key factors for improving the outcrossing ability of wheat thermo-photo sensitive genic male sterile（TPSGMS） line. A DH population derived from K239S/K92 S was constructed to investigate the inheritance of stigma exertion. K239 S and K92 S are TPSGMS lines with higher and lower stigma exertion rates（SER）, respectively. The SERs of parents, reciprocal crosses and the DH population were evaluated for two consecutive years. The results showed that no significant difference was observed in SER between F1 s of K239S/K92 S and K92S/K239 S,implying that stigma exertion was a trait controlled by nuclear gene（s）. In the DH population, the segregation of low and high SERs fitted to a ratio of 3 ∶1 by Chisquare test, suggesting that the stigma exertion of K239 S was controlled by one pair of recessive genes. In addition, the effects of temperature and humidity on the expression of stigma exertion were also discussed.

Influence of Soil Moisture and Air Temperature on the Stability of Cytoplasmic Male Sterility (CMS) in Maize (Zea mays L.)

Cytoplasmic male sterility (CMS) is a maternally inherited trait that suppresses the production of viable pollen. CMS is a useful biological tool for confinement strategies to facilitate coexistence of genetically modified (GM) and non-GM crops in case where it is required. The trait is reversible and can be restored to fertility in the presence of nuclear restorer genes (Rf genes) and by environmental impacts. The aim of this study was to investigate the influence of the level of irrigation on the stability of CMS maize hybrids under defined greenhouse conditions. Additionally the combination of irrigation and air temperature was studied. Three CMS maize hybrids were grown with different levels of irrigation and in different temperature regimes. Tassel characteristics, pollen production and fertility were assessed. The CMS stability was high in hot air temperatures and decreased in lower temperatures. The level of irrigation had no major effect on the level of sterility. The extent of these phenomena was depending on the genotype of CMS maize and should be known before using CMS for coexistence purposes.

大豆花药优势表达基因GmFLA22a调控雄性育性的功能研究

我国大豆对外依赖度高,加速提高大豆产量是目前亟需解决的问题。利用杂种优势是大幅提高作物产量的有效途径之一,近年来基于隐性核不育基因开发的智能雄性不育系统,为快速利用大豆杂种优势提供了可能。但是,大豆雄性不育基因研究相对滞后。本研究基于课题组大豆花器官转录组数据,筛选到在大豆早期花药中优势表达基因GmFLA22a,编码含有FAS1结构域的成束状阿拉伯半乳糖蛋白,亚细胞定位表明其可能在内质网中发挥功能。利用基因编辑技术获得Gmfla22a突变体,突变体植株在营养生长阶段与对照组相比没有明显差异,但在生殖生长阶段表现为结实率显著降低。Gmfla22a突变体花粉活力和花粉萌发率均无明显异常,组织切片并染色观察发现,突变体植株花药室壁增厚,花粉粒释放延迟、不完全,这可能是导致Gmfla22a结实率降低的原因。综上,本研究初步揭示GmFLA22a可能参与调控大豆雄性育性,为深入揭示其分子功能提供重要遗传材料,同时为大豆杂种优势利用提供基因资源和理论依据。

Cytological Investigation of Pollen Development in Sorghum Line with Male Sterility Induced by Sodium Ascorbate in Tissue Culture

Investigation of male sterility mutations is an effective approach for identification of genes involved in anther and pollen development. The comparison of “cytological phenotypes” of newly induced mutants with phenotypes determined by already known genes favors elucidation of genetic control of diverse microsporo- and gametogenesis stages. In this paper, we describe pollen development in the grain sorghum line Zh10-asc1 with mutation of male sterility. This line was obtained from callus culture treated by sodium ascorbate. A wide spectrum of abnormalities in microsporogenesis have been found, such as cytomixis, chromosomal laggards, chromosome disjunction, adhesion of chromosomes, disturbed cytokinesis, and others. In tapetum, the cells with one nucleus, with unequal nuclei, and with micronuclei have been observed. During pollen grain (PG) maturation abnormalities in starch accumulation and delay of development often took place. In mature anthers, a variety of pollen grain types have been revealed: fertile, of irregular shape, incompletely filled with starch, PGs delayed at the uni-nucleate or bi-nucleate gametophyte stages, with partially or fully degenerated contents, and with abnormal coloration. Variation in spectrum and the frequency of disturbances between the flowers of one and the same plant have been revealed. The reasons for significant genetic and epigenetic instability are discussed.

甘蓝显性雄性不育材料DGMS79-399-3不育性的遗传效应分析

采用两种不同的遗传分析模型，研究了甘蓝显性雄性不育材料DGMS79-399-3不育性的遗传效应。结果表明，运用GriffingⅡ的方法进行遗传效应的分析，就不育度而言，加性作用的方差占总的遗传方差为21．89％，而显性作用的方差为78．11％；广义遗传力为97．22％，狭义遗传力为21．23％。配合力的比较结果表明，5个不育亲本中，523-16的一般配合力最高，达3．17；特殊配合力最高的组合是606-7×102，达10．42。用6个世代联合分析的方法进行遗传规律的研究，结果表明，影响甘蓝显性雄性不育材料育性的最适遗传模型为-对加性-显性主基因＋加性-显性-上位性多基因模型（D模型），主基因的遗传率为82．03％～94．12％，微效基因的遗传率为0．14％-10．94％，两种遗传分析模型研究结果均表明：主基因的显性作用在不育性表达中占主导地位，但主基因的加性作用以及微效基因的影响也不可忽视。

Rapid Constructing a Genetic Linkage Map by AFLP Technique and Mapping a New Gene tms5

In this study, we reported the repaid construction of a molecular marker linkage map of rice (Oryza sativa L.). An F-2 population from the cross between Annong S-1 and Nanjing 11 was used to construct a genetic linkage map of rice. Total of 142 newly screened AFLP markers and 30 anchor markers (25 SSR markers and 5 RFLP markers) were mapped on the 12 chromosomes covering 1537.4 cM of rice genome. The average interval between these markers was 9.0 cM. The total work which usually was finished in more than one year was finished within only 3 months by one person. This is the first plant AFLP map developed in China. A new thermosensitive genic male sterile gene in rice, tms5, was Egged and mapped onto chromosome 2 during the development of the linkage map.

甘蓝型油菜核不育材料Shaan-GMS不育基因的RAPD标记

以825条10碱基随机引物对甘蓝型油菜Shaan-GMS转育的杂合近等基因系220AB的可育群体和不育群体进行PCR扩增,其中632条引物共扩增出2043条带,引物BA1102在220AB的可育群体及不育群体间扩增出2条多态性条带,BA1102.500只在220AB的不育群体中出现,BA1102.1000在220AB的不育群体中缺失。进一步对单株PCR分析表明,15株不育株都扩增出了BA1102,500条带;未扩增出BA1102.1000条带,而15株可育株的扩增结果相反,说明BA1102.500是与Shaan-GMS的显性核不育基因Ms相连锁的阳性带。在恢保关系相同的双显性核不育材料6CA的F_1可育和不育群体中,BA1102未获得多态性。

水稻光温敏雄性核不育系广占63S不育基因PTGMS2-1的遗传分析与分子定位

水稻光温敏雄性核不育系广占63S的不育基因来源于光敏核不育系农垦58S,其育性转换表现为温敏型,是迄今两系杂交水稻中应用最广泛的籼型光温敏核不育系之一。对广占63S/旱1587组合的F2分离群体进行不育基因的遗传分析,结果表明广占63S的不育性受1对隐性不育基因控制。利用SSR和InDel分子标记技术,结合BSA法,以广占63S与旱1587组合的F2分离群体为材料,将不育基因(暂命名为PTGMS2-1)定位于第2染色体标记S2-4与S2-27之间物理距离390kb的区间内,与两标记间的遗传距离分别为0.5和1.1cM,与标记S2-24共分离。

甘蓝型油菜核不育材料Shaan-GMS恢复基因的筛选及其遗传分析

从国内外77份甘蓝型油菜材料中筛选出1份Shaan-GMS的恢复材料"96-803",对其的遗传研究结果表明,Shaan-GMS育性恢复遗传机制符合2对核基因互作控制假说,假设不育基因为Ms,其对应的隐性可育等位基因为ms,Rf为Ms的显性抑制基因,rf为Rf的隐性等位基因,基因型Ms-rfrf表现为雄性不育,其他7种基因型都表现为雄性可育,则Shaan-GMS的基因型为Msmsrfrf,"96-803"的基因型为msmsRfRf,隐性测交系"84004"的基因型为msmsrfrf。"96-803"和其他8份材料的测交结果表明,Shaan-GMS同6CA恢保关系相同。