Comparative Studies on the Changes of Microtubule Distribution and Reorganization During the Meiotic Stages of Development in Normal (IR36) and a Temperature/photoperiod Sensitive Male Sterile Line (Peiai 64S) of Rice ( Oryza sativa )

Changes in the pattern of organization of microtubules in the meiotic stages of development of pollen (i.e. from pre-meiotic interphase to more or less metaphase I) of a normal (IR36) and a temperature/photoperiod sensitive male sterile line (Peiai 64S) of rice were studied using immunofluorescence confocal microscopy. In IR36, from pre-meiotic interphase to metaphase I, the pattern of microtubule distribution in the meiocytes underwent a series of changes. Some new organizational patterns of microtubules (that have not been described before) were observed during microsporogenesis, including the existence of a broad band of perinuclear microtubules at the diakinesis stage of development. The pattern of microtubule distribution in the meiocytes of the male sterile line, Peiai 64S, was quite different front that seen in IR36. In Peiai 64S, the microtubules showed abnormal patterns of distribution from pre-meiotic interphase to metaphase I. For example the broad band of perinuclear microtubules seen at diakinesis in IR36 was much disorganized and loosened in Peiai 64S. The spindles formed were also very abnormal and different from the normal spindle. The appearance of abnormal microtubule distribution in the early stages of microsporogenesis may contribute to the malformation and ultimate abortion of pollen in Peiai 64S.

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.

Isolation and Analysis of the Promoter of OsRacD from PhotoperiodSensitive Genic Male Sterile Rice

By using OsRacD cDNA as probe to screen the genomic library of photoperiod sensitive genic male sterile rice line Nongken 58S, a positive clone containing 2 kb promoter and 396 bp coding region of OsRacD was obtained. Compared with the promoter of OsRacD cloned by reverse PCR from normal rice variety Nongken 58 （Nongken 58N）, the homology was 99.8%, and the different nucleotides were outside the predicted response elements in promoter, suggesting that the fertility between rice varieties Nongken 58S and Nongken 58N under the long-day conditions was not attributed to the difference in the structure of OsRacD upstream regulation sequences, but to the developmental regulation of gene differential expression.

Factors Influencing the Outcrossed Seed-Setting Obstacles of Photo-thermo Sensitive Genie Male Sterile Rice

Using photo-thermo sensitive genie male rice (PTGMS) Pei' ai 64S, W7415S, W6154S, N26S, Annong S, Nongken 58S, 7001S and 5088S as female parents and conventional indica lines 8258 and U89 as male parents, the factors affecting outcrossed seed-setting were analyzed. The PTGMS had obstacles in outcrossed seed setting influenced by inheritance and environment at varying degrees. Environmental temperature was regarded as the main factor that resulted in the outcrossed seed-setting obstacles. The sensitive stage was at the early stage of grain filling for outcrossed seed setting. There existed remarkable differences at the sensitivity stage, the duration of sensitive period, the sensitive level and the effective level of outcrossed seed-setting obstacles caused by environmental temperature among different PTGMS lines. Therefore, attention should be paid to outcrossed seed-setting obstacles in selection and utilization of PTGMS lines.

Inheritance of the Male Sterility in a New Photo/Thermo-Sensitive Genie Male Sterile Line B06S of Rice

The major male sterile genes in a new photo/thermo-sensitive genie male sterile (PTGMS) line B06S of rice were analyzed by the manipulation of mixture distribution theory. The results indicated that a pair of major male sterile nuclear genes with large effects were responsible for controlling the male sterility of B06S.

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.

Progresses and Strategies of Gene Mapping and Isolating of Photo(thermo) sensitive Genic Male Sterile Rice

Considering the research on classical genetics of photoperiod(therm) sensitive genic male sterile rice, it is important to select the sterile lines and their segregating population controlled by one pair of gene in mapping and isolating sterile genes. It is discussed the advantages, disadvantages and the reasons leading to various mapping results of chromosome location of sterile genes through gene marker, isozyme marker and DNA marker techniques. In comparison to isolation of photo(thermo) sensitive sterile genes via various plant gene cloning techniques, it was concluded that map based cloning was acceptable, but it is still difficult to locate the loci of sterile genes within 1cM. On the other hand, “sensitivity to environment”, an important characteristic of sterile lines can be fully utilized by DD PCR and (or) RDA techniques. Therefore, these two techniques were considered as the effective ways to isolate sterile genes.

Studies on the Photoperiod Sensitive Characters of Male Fertility Alteration of Peiai64S' Main Male Genic Sterile Gene

Peiai64S, an indica male sterile rice with a male fertility alteration under different environments, is selected from the offspring of indica rice crossed with Nongken58S. Nongken58S, a japonica pho-toperiod sensitive genie male sterile rice (PGMS), deriving from a natural mutant plant individual of normal japonica rice variety, Nongken58, is used as a male sterile gene donor of Peiai64S. But Peiai64S is not a typical PGMS rice, the male fertility is sensitive to temperature just as thermo-sensitive genie male sterile rice (TGMS). We have selected typical PGMS plants in F2 population of Peiai64S× Nongken58, whose ratio of fertile plants to sterile plants is nearly 3:1. The sterility inheritance conformed to one pair of gene segregation model. The result indicates the main male sterile gene in Peiai64S is not other than the PGMS gene, and comes from Nongken58S. The genetic background affects effective expression of the PGMS gene. This suggests that we ought to focus on optimizing the genetic background of the PGMS gene in PGMS rice breeding, and select an ideal genetic background as a transgenic background in molecular breeding.

光/温敏核不育系的不育机理及两系杂交稻的发展与展望

本文回顾了中国两系杂交水稻的发展历史;介绍了两系法中光/温敏型核不育系遗传资源的发现和选育;总结了植物中光温敏型雄性不育的遗传学和细胞学机制;并对水稻两系法中光/温敏型雄性不育系的遗传资源优化及育种策略提出了建议。

Identifying and mapping cDNA fragments related to rice photoperiod sensitive genic male sterility

The differentially expressed cDNA fragments have been obtained by differential screening with cDNA-RAPD technique in photoperiod sensitive genic male sterile (PGMS) rice. Some of them have been reassessed with Northern blot hybridization, from which a PGMS-related positive fragment, RPG43, has been identified. Further analysis on RPG43 with Southern blot and RAPD indicates that the fragment is a single-copy sequence and its mRNA has been processed after transcription. Sequence analysis reveals that RPG43 is 744 bp in length and contains a 60 bp region (from 126th to 185th bp) showing 72% homology to a human DNA sequence, pac pDJ-356d6, on chromosome 11. So it is a new sequence found in plant and its GenBank access number is AF126027. In addition, RPG43 has been mapped to a position 3.8 cM away from RFLP marker R1553 on chromosome 5 of rice.

Construction and characterization of a bacterial artificial chromosome library of thermo-sensitive genic male-sterile rice 5460S

In order to develop a detailed physical map of the thermo-sensitive genie male-sterile (TGMS) gene-encompassing region and finally clone the TGMS gene, a high-quality rice bacterial artificial chromosome (BAC) library from TGMS rice 5460S was constructed. The method of constructing BAC library was examined and optimized. The 5460S library consists of 19 584 BAC clones with an average insert size of 110 kb, which represents about 5 times rice haploid genome equivalents. Rice inserts of up to 140 kb and 250 kb were isolated and appeared stable after 100 generations of serial growth. Hybridization of BAC clones with mitochondria! and chloroplastic genes as probes demonstrated that this library has no organellar contamination. The 5460S library was screened with 3 molecular markers linked to tms 1 gene as probes and at least 1 BAC clone was identified with each probe. The insert ends of positive clones were successfully isolated using thermal asymmetric interlaced PCR (TAIL-PCR) technique.

Long non-coding RNAs play an important role in regulating photoperiod-and temperature-sensitive male sterility in rice

Rice(Oryza sativa L.)is a major food crop for more than half of the world’s population.Therefore,increasing rice production is of great importance.The successful development of hybrid rice in the 1970s was an important achievement for increasing yield potential,since hybrid rice varieties produce higher yields than inbred varieties(Cheng et al.,2007).In plants,male sterility refers to the inability of producing dehiscent anthers and functional pollen(Chen and Liu,2014).

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.

Temperature-sensitive splicing is an important molecular regulation mechanism of thermosensitive genic male sterility in rice

Photoperiod and temperature-sensitive genetic male sterility (PGMS and TGMS) plants have a number of desirable characteristics for hybrid production. Two-line hybrids developed using the PGMS/TGMS system now account for a large proportion of rice production in China. In this paper, we summarize recent advances on molecular regulation mechanisms and genetics of PGMS/TGMS in rice. We suggest that temperature-sensitive splicing, an important posttranscriptional regulatory mechanism in modulating gene expression and eventually development and differentiation, is also an important molecular regulation mechanism of TGMS in rice. We review those factors involved in temperature-sensitive splicing like cis splice site, snRNA, trans premRNA splicing protein and SR proteins, and delineate that splicing could be regulated by a complex cell signaling pathway. These might shed light on other unknown molecular PGMS/TGMS mechanisms.

湖北光周期敏感核不育水稻农垦58s花药中的某些生化代谢特点

湖北光周期敏感核不育水稻农垦58s单核早期的不育花药的线粒体呼吸速率和LOX活性分别较可育株低11.9％和5％,而单核晚期相应较可育株低18.4％和17.3％。花药发育从单核期至三核期,可育花药的AsA和GSH含量增高,而不育花药仅分别相当于可育株的35—55％和22—32％,并有脂质氢氧化物积累。随着花药发育,可育花药的AsA-POD,GR和6-GPDH活性逐有增高,至三核期达到最高。而不育花药,随花粉败育,在单核早期至三核期,AsA-POD,GR和6-GPDH活性逐渐降低,至三核期,其活性分别为可育株的26％,22％和19％,不育花药的ME和MDH活性亦较可育株低。IDH活性在单核晚期为可育株的47—80％。细胞还原势低是不育花药特征之一。低的还原势可能导致活性氧代谢失调和花药不育。

光敏核不育水稻的光温反应研究——Ⅱ.人工控制条件下粳型光敏不育系的育性鉴定

在人工控制条件下研究了光照时间和温度对农垦58S及以此为基因源转育的其他粳型光敏不育系育性的影响。结果表明,供试粳型光敏不育系的育性受光照时间和温度的双重影响,在15.0h光长与29.6℃平均温度(最高与最低温度分别为33.0℃与28.0℃)的长光照高温条件下,自交结实率为0或接近于0;在12.0h光长与23.6℃平均温度(27.0/22.0℃)的短光照低温条件下,自交结实率较高;在长光低温(15.0h/23.6℃)和短光高温(12.0h/29.6℃)下,育性出现不同程度的转变。不同材料的育性对光温反应存在着差异,提示遗传背景对育性表达可能有重要作用。本研究结果有助于对自然条件下光敏不育系夏季制种纯度不高而秋季警种产量又较低的现象在理论上给予合理的解释。

光敏核不育水稻的光温反应研究 Ⅲ.减数分裂期温度对两个籼稻光敏不育系育性转换的影响

在人工控制条件下研究了在15小时长光照下减数分裂期的不同温度(23.3～30.3℃)对籼稻光敏不育系W6154S和5460S育性转换的影响。结果表明,温度对育性的影响因温度的高低及处理持续时间长短而异,不同的材料对温度的反应不同。5460S从不育转为可育的临界温度在26.4℃左右,而W6154S在处理温度范围内均出现自交结实现象,表明供试的W6154S株系育性转换的临界温度可能超过30.3℃。提出了深入研究影响籼稻光敏不育系育性转换的临界温度的建议。

一种紫色水稻的遗传及其在光敏不育系育种中应用的研究

研究表明，本院获得的一种紫色水稻的植株色遗传受控于C、A、Pl3个独立基因座位上显性基因的互补作用，另有一独立的显性基因对Pl基因的表达起抑制作用．由于该抑制基因在籼稻中的高频率存在，因而，紫稻与一般绿稻品种杂交F1多表现为绿株．紫稻光敏不育（株）系的不育性表达和配合力表现，均可达到与普通光敏不育系相似的水平．本文还讨论了选育籼型紫稻光敏不育系设想的可行性．

光敏核不育水稻育性转换的温度敏感期研究

在14.5小时长光照下,利用人工气候箱对农垦58S和W6154S于幼穗分化不同时期分别进行不同温度处理。育性结果表明农垦58S的育性转换温度敏感期为颖花原基分化期至单核花粉期,W6154S的温敏期为雌雄蕊形成期至单核花粉期。农垦58S的温敏期较长,育性受低温影响后在高温下要较长时期才能恢复不育;W6154S育性易受低温影响,但温敏期较短,在高温下不育性恢复快。在光敏核不育水稻育性感温性鉴定中,建议在雌雄蕊形成期至减数分裂末期进行温度处理。

水稻光敏核不育系N422s的广亲和性及分类地位初探

N422s是以晚粳型光敏核不育系7001s为供体,广亲和系轮回422为受体,经过杂交转育而成的稳定的中粳型光敏核不育系。亲和性研究表明,N422s不仅与4个标准测验种杂交产生具有正常育性的F_1代,而且与30个不同类型的地方品种(系)杂交F_1代也表现较高的育性。因此,该不育系具有广亲和性及配组自由度大的特点。N422s在形态指数及酚反应上表现为粳型,在杂交亲和力上也偏粳。但是,选用与籼粳分类有关的多位点同工酶进行分析,结果表明它属于籼稻。在光温生态反应上,它也表现出与原始亲本培迪(Padi)相似的反应型。考虑到N422s的广亲和性来自印度尼西亚的平原地方品种培迪,在分类地位上它归属于粳亚种下的爪哇群。