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.

pms3 is the locus causing the original photoperiod-sensitive male sterility mutation of‘Nongken 58S'

Photoperiod-sensitive genie male sterile (PSGMS) rice is a very useful germplasm for hybrid rice development. It was first found as a spontaneous mutant in a japonic a cultivar 'Nongken 58' . pms3 on chromosome 12 was determined to be the locus where the original PSGMS mutation occurred, changing the normal cultivar Nongken 58 to PSGMS Nongken 58S. Large amounts of RAPD and AFLP analyses were also conducted for the fine mapping of the pms3 genomic region, which resulted in 4 molecular markers linked to pms3. Although these markers somewhat increased the marker density of this region, the pms3 locus is still located in a marker-sparse region.

Immunohistochemical Analysis of IAA in Anthers of the Photoperiod-sensitive Genic Male-sterile Rice

The immunohistochemical localization of IAA and the comparison of their relative levels were carried out for the first time in the anthers of Nongken 58S and its wild type Nongken 58 (Oryza sativa subsp. japonica) after long_day and short_day treatments. The distribution of free_IAA in anthers and its dynamic variation could be reflected by this method. The results showed that the IAA level in the anthers of Nongken 58S after long_day treatment was much lower than that in short_day_treated Nongken 58S and those in wild type Nongken 58 in five stages from pistil and stamen primordia formation to late uninucleate stage. The possible reasons for IAA deficiency in Nongken 58S_LD anthers and its relationship with fertility alteration were also discussed.

Mapping of a gene for photoperiod-sensitive genic male sterility in Nongken 58s on chromosome 5 of rice

A photoperiod-sensitive genic male sterile (PGMS) rice was found in 1973 as a spontaneous mutant of Nongken 58, a japonica variety. Pollen fertility of Nongken 58s (N58s) is completely sterile when grown under long-day conditions, whereas fertile under short-day conditions. This PGMS was found to be controlled by one or two recessive gene(s), of which one gene(pms)was linked to a marker gene(d-1) on chromosome 5. In order to identify a more precise location of the pms, we analyzed the populations of BCFand BCFof N58s//N58s/KL211(v-10, virescent) and N58s//N58s/KL520 (gh-1, gold hull). The marker genes v-10 and gh-1 are located on the flanking region of d-1. The F, plants of two crosses were fertile. The number of fertile and sterile individuals in BCFfit

Immunoassay of Phytochrome A Content in Photoperiod-sensitive Genic Male-sterile Rice

A rice mutant (Oryza sativa L. Nongken 58S) 'photoperiodsensitive male-sterile rice' (PGMR) is sterile under long day-length (LD), but fertile in short days-length (SD). Phytochrome (Phy) has proved to be the photoreceptor involved in photoperiod-induced male sterile process in PGMR.To speculate how phytochrome functions, PhyA levels in leaf extracts of PGMRand wild-type rice (Oryza sativa L. Nongken 58) under different photoperiods were measured by means of a sandwich enzyme-linked immunosorbent assay (ELISA). The top two leaves of treated rice plants were sampled at the end of the last dark phase for 10 cycles at photoperiod-sensitive stage for fertility alteration in the mutant. Compared with LD treatment, the SD treatment resulted in 39% increase of relative PhyA content (per unit fresh weight) in PGMR, but only in 18% increase in its wild-type. In addition, after 10 cycles of end of far-red irradiations of day,the heading and flowering dates of PGMR were delayed for 2 days, while its male fertility almost remained unchanged. It is well known that the end of day far-red responses are mediated by PhyB.These results suggested that in PGMR PhyA took part in regulation of male sterility, hut PhyB was involved in mediating flowering time.

Advances in DNA methylation and its role in cytoplasmic male sterility in higher plants

The impact of epigenetic modifications like DNA methylation on plant phenotypes has expanded the possibilities for crop development.DNA methylation plays a part in the regulation of both the chromatin structure and gene expression,and the enzyme involved,DNA methyltransferase,executes the methylation process within the plant genome.By regulating crucial biological pathways,epigenetic changes actively contribute to the creation of the phenotype.Therefore,epigenome editing may assist in overcoming some of the drawbacks of genome editing,which can have minor off-target consequences and merely facilitate the loss of a gene’s function.These drawbacks include gene knockout,which can have such off-target effects.This review provides examples of several molecular characteristics of DNA methylation,as well as some plant physiological processes that are impacted by these epigenetic changes in the plants.We also discuss how DNA alterations might be used to improve crops and meet the demands of sustainable and environmentally-friendly farming.

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.

RAPD and ISSR Markers of Fertility Restoring Gene for Aegilops kotschyi Cytoplasmic Male Sterility in Wheat

LK783 was found to be a good fertility restorer for K-type male sterility of wheat (Triticum aestivum L.). RAPD and ISSR (inter-simple sequence repeat polymorphism) markers were employed to map the major restoring gene in LK783. Maintainer and restorer DNA pools were established using the extreme sterile and fertile plants among KJ5418A//911289/LK783 F 1 population, respectively. Four hundred and eighteen RAPD primers and 33 ISSR primers were used for screening polymorphisms between the two pools, and amplification bands using a RAPD primer of OPK18 and an ISSR primer of UBC-845 were found polymorphic between the two pools. Linkage analysis showed that OPK18 450 and UBC-845 800 were linked to the restoring gene in LK783. The distance between the restoring gene and OPK18 450 was (15.07±6.28) cM (centiMorgan), with the distance between the restoring gene and UBC-845 800 being (8.20±4.85) cM. The marker of UBC-845 800 was located on chromosome 1BS by amplifying nulli-tetrasomics and 1B ditelosomics of Chinese Spring with the primer of UBC-845, indicating that the restoring gene in LK783 was located on 1BS. The breeding for new fertility restorer lines of K-type cytoplasmic male sterility of wheat would be facilitated by using the two markers.

Microtubule Structure and Male Sterility in a Gene-Cytoplasmic Male Sterile Line of Rice, Zhen Shan 97A

Histological changes that occur during microsporogenesis are documented in a gene-cytoplasmic male sterile rice ( Oryza saliva L.) line, Zhen Shan 97A, its maintainer line, Zhen Shan 97B, and the restorer line, Ce64 of a Mine hybrid rice production system. In the restorer line, Ce64, the developing microsporocytes have dense cytoplasm and a distinct set of circumferential microtubules around the nucleus. Successive cytokinesis results in the formation of tetrads. The microtubules within the cells of tetrads and microspores radiate from the surface of the nucleus towards the outer edge of the cytoplasm. Subsequent pollen development is normal. During the course of microspore formation tubulin speckles can be found in the cytoplasm. The general pattern of development and microtubule organization in the maintainer lined Zhen Shan 97B, is similar to Ce64, except that a few more tubulin speckles appear during microspore formation. In the case of the mate sterile line, Zhen Shan 97A, a number of abnormalities can be discerned during early microsporogenesis. These include vacuoles forming within the developing microsporocyte and faintly stained microtubules with no defined distribution pattern. Prominent tubulin speckles are common within the cytoplasm. For those microsporocytes that undergo meiosis, no defined organizational patterns of microtubules can be found within the tetrad. All microspores abort soon after. Abnormalities and defects in microtubule organization observed in Zhen Shan 97A showed that complex interactions between the cytoplasm and the nucleus began at very early stage of microsporocyte development.

Construction and Identification of HSP70 Antisense RNA Expression Vector for Genetic Engineering Male Sterility in Plant

[ Objective] In order to study the relation between the HSPTO gene and male sterility of plant further. [ Methods ] Anther specific expression promoter Osg6B of rice was coloned by PCR then connected with HSP70 antisense fragment to construct HSPTO antisense expression vector. The expression vector was identified by PCR experiment and enzyme digestion. [ Result] The sequence of coloned Osg6B promoter had 97% homology to the published sequence, and the cis-regulatory element in promoter area was integrated. HSP70 antisense expression vector driven by the promoter Osg6B was confired by colony PCR and enzyme digestion. [ Conclusion] The construction of expression vector would lay solid foundation for utilization of genetic engineering male sterility of plant.

Research of Fertility Standard on Male Sterility of Lycium chinensis

Botanical features of "YX-1" reproductive organ and bearing rate by number of pollen granules in pollen sacs of Lycium chinensis was observed and researched through field investigation, smear preparation and paraffin sections. YX-1 of Lycium chinensis was determined as incomplete male sterility and further classified into complete sterile type, sterile type I and sterile type II. The fertility standard of male sterility of Lycium chinensis was preliminarily proposed to establish a basis for crossbreeding of male sterility of Lycium chinensis.

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.

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.

Breeding and Cultivation Technique of Recessive Genic Male Sterility Hybrid Wheat New Variety Xinan 112

Xinan 112 is the hybrid combination（11S12） by wheat recessive genic male sterility line 2011Z1 （08L5070） and restoring line K152-2, particpating in the regional test of 2011-2012, 2012-2013 and production test of 2013-2014 in Chongqing. The results showed that 3 years average yield was 4 167.5 kg/hm2, which was increased 10.5% compared with CK Yumai 7, 1 000-grain weight was 45.8 g, which was 1.7 g heavier than the control; grain number per ear was 39.3, more than 1.6 grains compared with CK. The results of 2 years quality determination were： bulk density of 811 g/L, falling number of 353 s, crude protein of 15.15%, wet gluten of 31.2%, water adsorption of 62.9 ml/100 g, formation time of 5.5 min, stable time of 6.5 min, softening degree of 90 F.U., and powder quality coefficient of 96 mm. Therefore, Xinan 112 is a high yield and high protein gluten wheat variety and is suitable for cultivated in Chongqing and climate contion similar areas.

Technical Specification for Producing Hybrid Pepper Seed Using Three-line Male Sterility

This paper described the whole process of three line hybrid pepper seed production in detail, including requirement of the seed production base, parent culti- vation, field management, and specified the key operation techniques in seed pro- duction, such as parental impurity removal to preserve pure state, pollen collection, pollination and seed collecting essentials. This specification is of guiding significance for the production of hybrid pepper seed and ensuring the purity of hybrid pepper seed.

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.

Research Advances in Molecular Mechanism of Thermo-sensitive Genic Male Sterility in Plants

Thermo-sensitive genic male sterile （TGMS） lines have specific superiority in heterosis utilization of crops. So far, thermo-sensitive genic male sterile lines have been found in many plants and are widely used in two-line hybrid breeding. With the rapid development of molecular biology, the molecular nature of thermo-sensitive genic male sterility has been revealed, which lays the foundation for further devel- opment and utilization of thermo-sensitive genic male sterile lines. In this study, the molecular mechanisms of fertility conversion of plant thermo-sensitive genic male sterile lines were reviewed from gene molecular mapping and gene differential ex- pression, and the mechanisms of gene differential expression in thermo-sensitive genic male sterile lines were further discussed.

Mapping of Fertility Restoring Gene for Aegilops kotschyi Cytoplasmic Male Sterility in Wheat Using SSR Markers

LK783 was found to be a good fertility restorer for K-type male sterility of wheat. Microsatel-lite markers were employed to map the major restoring gene in LK783. Maintainer and restorer DNA pools were established using the extreme sterile and fertile plants among (KJ5418A//911289/LK783)F1 population, respectively. Seventy-nine sets of SSR primers were screened for polymorphism between the two pools, 6 of which were found polymorphic. Linkage analysis showed that Xgwm11, Xgwm18, Xgwm264a and Xgwm273 were linked to the restoring gene in LK783, while Xgwm11, Xgwm18 and Xgwm273 were co-segregated. The distance between the Rf gene in LK783 and the three co-segregated markers was 6.54 ± 4.37 cM, the distance between Rf gene and Xgwm264a was 5. 71 ± 4.10 cM. The four SSR markers were located on chromosome IBS by amplifying the DNA of nulli-tetrasomics and ditelosomics of CS with the 4 sets of primers, indicating that the major restoring gene in LK783 was located on IBS, but the relative location of the gene was different from Rfv1, allelism of the two genes should be further investigated. The breeding for new fertility restorer lines of K-type cytoplasmic male sterility in wheat would be facilitated by using the four polymorphic markers.

Abortive Process of a Novel Rapeseed Cytoplasmic Male Sterility Line Derived from Somatic Hybrids Between Brassica napus and Sinapis alba

Somatic hybridization is performed to obtain significant cytoplasmic male sterility （CMS） lines, whose CMS genes are derived either from the transfer of sterile genes from the mitochondrial genome of donor parent to the counterpart of receptor or production of new sterile genes caused by mitochondrial genome recombination of the biparent during protoplast fusion. In this study, a novel male sterile line, SaNa-IA, was obtained from the somatic hybridization between Brassica napus and Sinapis alba. The normal anther development of the maintainer line, SaNa-IB, and the abortive process of SaNa-IA were described through phenotypic observations and microtome sections. The floral organ of the sterile line SaNa-IA was sterile with a shortened filament and deflated anther. No detectable pollen grains were found on the surface of the sterile anthers. Semi-thin sections indicated that SaNa-IA aborted in the pollen mother cell （PMC） stage when vacuolization of the tapetum and PMCs began. The tapetum radically elongated and became highly vacuolated, occupying the entire locule together with the vacuolated microspores. Therefore, SaNa-IA is different from other CMS lines, such as ogu CMS, pol CMS and nap CMS as shown by the abortive process of the anther.

Mechanism of Sterility and Breeding Strategies for Photoperiod/Thermo-Sensitive Genic Male Sterile Rice

To understand the male sterility mechanism of photoperiod/thermo-sensitive genic male sterile [P（T）GMS] lines in rice, the research progress on genetics of photoperiod and/or temperature sensitive genic male sterility in rice was reviewed. A new idea was proposed to explain the sterility mechanism of P（T）GMS rice. The fertility transition from sterile to fertile is the result of cooperative regulation of major-effect sterile genes with photoperiod and/or temperature sensitive genes, but not the so-called pgms gene in P（T）GMS rice. The minor-effect genes, which exhibit accumulative effect on sterility, are the important factors for the critical temperature of sterility transition. The more minor-effect genes the sterile line holds, the lower the critical temperature of sterility transition is. The critical temperature of sterility transition will be invariable if all the minor-effect genes are homozygous. The strategies for breeding P（T）GMS rice were also proposed. The selective indices of critical photoperiod and temperature for sterility transition should be set according to varietal type and ecological region. Imposing selection pressure is a key technology for breeding P（T）GMS rice with lower critical temperature for sterility, and improving the comprehensive performance of the whole traits and combining ability is vital for breeding P（T）GMS rice lines.