Genetic analysis of male sterility in rice mutants with environmentally influenced levels of fertility

Summary Twenty-six male sterile plants grown in the field were recovered in the M7 generation from ethyl methane sulfonate-treated material of the rice cultivar M-201. Fertility increased five-fold when ratooned plants from the field were grown in a growth chamber with a 12 hour daylength. Crosses between mutant and normal fertile cultivars produced fertile F₁ plants. Female fertility was normal as judged by percent seed set from unbagged panicles of parental and recombinant lines. Transgressive segregation for fertility was observed for all crosses in the F₂ and F₃ generations. Five of 37 F₃ male sterile plants showed moderate levels of seed fertility under winter greenhouse conditions and reduced seed set when transplanted to summer field plots. Fertility data from reciprocal crosses suggested cytoplasmic factors had little or no effect on levels of male sterility in the mutant lines. Chi-squared analyses of F₂ and F₃ generation results indicated male sterility of the mutants is conditioned by two nuclear genes with epistatic effects.     

Induction of photoperiod sensitive genetic male steriles for use in hybrid rice seed production

The most notable photoperiod sensitive genetic male sterile in rice is the Nongken 58S line in China. Two sources of environmentally sensitive genetic male sterile mutants were found in California. The photoperiod-sensitive genetic male steriles (PGMS) have the potential for reducing hybrid rice breeding from the present 3-line system to a 2-line system. The long-range objectives of the present project were to induce an array of genetic male steriles in rice, and then to evaluate these at different day lengths in order to find steriles that become fertile in selected environments. Three genetic male steriles were selected from gamma irradiation of southern US cultivars. Inheritance of these mutants was studied through progeny tests in M₅ to M₇ generations and through fertility characterization of pollen and spikelets. Seed set on steriles under open pollination ranged from a low of 8.1% for Cypress 1819 to a high of 32.9% for Kaybonnet 1789. This revised version was published online in August 2006 with corrections to the Cover Date.     

Isolation and genetic characterization of a fertility-restoring revertant induced from cytoplasmic male sterile rice

Summary A male fertile revertant was isolated from M₁ of a cytoplasmic male sterile indica rice line II-32A, the dry seeds of which were treated with ⁶⁰Co- rays at a dose of 290 Gy. The acquired revertant T24 was morphologically and agronomically similar to II-32B, the maintainer of II-32A. Testcrosses of the revertant with II-32A and Zhenshan 97A showed that the revertant was able to restore the fertility of CMS lines. Genetic analysis of the progenies between T24 and II-32A, Zhenshan 97A XieqingzaoA and DZhenshan 97A, which have different cytoplasms, showed that the fertility restoration of four CMS lines by T24 involved one nuclear gene, indicating that T24 was a result of the mutation of one nuclear gene. The mechanism of the restoration of CMS line by T24 was obviously different from other restorers such as Minghui 63 and 20964, which were shown to behave in two gene mode in fertility restoration. The discovery of the revertant T24 contributes to the understanding of CMS and fertility restoration of CMS in rice. The T24 and its parent II-32A may constitute a pair of near isogenic lines for the restoring gene, which should be valuable materials for molecular genetic analysis of CMS.     

一个水稻雄性不育突变体的遗传分析和基因定位

ms-np是一个源于自然突变的水稻雄性不育突变体,明显较正常植株矮小,叶色浓绿。小花解剖观察发现,突变体小花花丝细长,花药干瘪,呈白色透明状,但雄性器官的数量和雌性器官正常。碘染证实,突变体的花药壁内没有花粉粒着色,是一个典型的无花粉型雄性不育材料。5个F₂和2个BC₁F₁群体的遗传分析显示,该突变性状受1对隐性基因控制。对组合ms-np/M63衍生F₂不育单株的连锁分析表明,ms-np(t)基因位于水稻第6 染色体微卫星标记RM541和RM343之间,遗传距离分别为15.2 cM和7.9 cM。     

一个水稻雄性不育突变体的遗传分析和基因定位

ms-np是一个源于自然突变的水稻雄性不育突变体,明显较正常植株矮小,叶色浓绿。小花解剖观察发现,突变体小花花丝细长,花药干瘪,呈白色透明状,但雄性器官的数量和雌性器官正常。碘染证实,突变体的花药壁内没有花粉粒着色,是一个典型的无花粉型雄性不育材料。5个F₂和2个BC₁F₁群体的遗传分析显示,该突变性状受1对隐性基因控制。对组合ms-np/M63衍生F₂不育单株的连锁分析表明,ms-np(t)基因位于水稻第6 染色体微卫星标记RM541和RM343之间,遗传距离分别为15.2 cM和7.9 cM。     

Interspecific cytoplasm substitutions of an Indica strain of Oryza sativa L. and O. Glaberrima Steud

Summary To study differential nucleus-cytoplasm interactions between the two cultivated rice species, Oryza sativa and O. glaberrima, cytoplasmic substitution lines were made by using a glaberrima strain (G) and an Indica strain of sativa (S). The G cytoplasm had no adverse effect on pollen development when combined with the nucleus of S. On the other hand, when the S cytoplasm was combined with the G nucleus, the substitution line showed no seed set because of male sterility although the pollen grains were normally stained with I₂-KI solution. A dominant gene derived from S strain seemed to cause anther indehiscence in the substitution line. Further, a restorer gene (Rf _j)from Akebono of Japonica type was effective on pollen restoration in the male sterile line, suggesting that the S cytoplasm is the same as those of Japonica type in terms of a fertility-restoring system.This paper is Genetic studies of speciation in cultivated rice. 4.     

水稻体细胞无性系雄性不育突变

对5个类型的水稻不育系进行了幼穗培养, 在红源A、 包源A和W6154s中, 共获得了10例雄 性不育变异株, 水稻花粉败育可分为无花粉、 典败、 圆败和染败四种类型。 发现了不育 花粉败育类型之间可以相互转换现象。 对雄性不育变异株用一批现有CMS不育系的保持系和恢复系进行测交和回交, 有的变异株其 恢保关系发生了变化,     

Effects of low temperature storage on the pollen of Brassica campestris,B. oleracea and B. napus

Summary Four indica cultivars viz. Kalinga-I, Ptb. 10, IR 27280-13-3-3-3 and Co. 41 were found to possess male sterile cytoplasm with fertility restoring genes while the cultivar Krishna was found to maintain the male sterility in all the cases. All the plants in the F₁ of Kalinga-I × Krishna were observed to be completely male sterile and continued to show complete pollen sterility in subsequent backcross generations when backcrossed with recurring pollen parent, Krishna. Thus, it was posible to develop a new cytoplasmic-genetic male sterile line in indica rice (Krishna A) with Kalinga-I male sterile cytoplasm and this male sterile cytoplasm was found to be genetically different from others. Further, the newly developed male sterile line (Krishna A) was observed to be tolerant for low temperature at seedling stage.     

Identification and inheritance of male sterility in groundnut (Arachis hypogaea L.)

Summary Some plants without pods but with gynophores were observed in two F₄ progenies of two crosses of goundnut (Arachis hypogaea L.). The flowers on these plants had translucent white anthers with no or a few sterile pollen grains. Three such plants in the succeeding generation were hand pollinated with pollen from a short-duration Indian cv. JL 24. The resulting F₁ hybrid plants (male sterile x JL 24) were normal. Chi-square tests for segregation for male fertile and male sterile plants in F₂ and F₃ generations indicated that the male sterility in these crosses of groundnut is governed by two recessive genes. We designate these genes as ms₁ and ms₂ with ms₁ms₁ms₂ms₂ being a male sterile genotype.Submitted as ICRISAT J. A. No. 1812.     

Pollen production in soybeans with respect to genotype,environment, and stamen position

Summary Our objective was to determine the average numbers of pollen grains from fertile plants (Ms ₁) and the average numbers of coenocytic microspores from genetic male sterile plants (ms ₁ ms ₁) in soybeans, Glycine max L. Merr. Comparisons were made between the average numbers of pollen grains and the average numbers of coenocytic microspores with respect to environment where plants were grown and to stamen position in the flower. Five male sterile lines were used. They included the North Carolina ms ₁ mutant, the cultivar Hark with the ms ₁ gene, and mutants identified as the Urbana, Tonica, and Ames male steriles. Three environments used were the Agronomy Farm, University of Georgia, Athens, Georgia; the Agronomy and Agricultural Engineering Research Center, Iowa State University, Ames, Iowa; and the Agronomy Greenhouse, Iowa State University, Ames, Iowa.Pollen production from fertile plants varied from 374 to 760 pollen grains per anther among genetic lines and environments. This variation may be an important consideration in selecting a male parent to use as a pollinator for hybrid seed production.Among fertile plants, the average numbers of pollen grains per anther of the separate stamen and and of the lower whorl of stamens were significantly different only in greenhouse-grown plants. Among male sterile plants, the average numbers of coenocytic microspores per anther of the separate stamen and of the lower whorl of stamens were significantly different in three genotype x environment combinations. These three exceptions did not conform to any genetic or environmental pattern. Deviations from the expected ratio of 4 pollen grains from fertile plants: 1 coenocytic microspore from sterile plants were attributed to initial differences in the average number of microspore mother cells between the two genotypes.Joint contribution: Agricultural Research Service, USDA, North Central Region, and Journal Paper No. J-8910 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011; Project 2107.     

Relationship Between Phytohormones and Male Sterility in Thermo-Photo-Sensitive Genic Male Sterile (TGMS) Wheat

Summary Fertility alternation normally occurs in a novel type of thermo-photo-sensitive genic male sterile (TGMS) wheat whose recessive genes in the nucleus are expressed as virtually complete sterility under lower temperature and shorter daylight conditions, but as normal fertility under higher temperature and longer daylight conditions during the developmental period from meiosis of pollen mother cells (PMCs) to the early mononucleate stage of microsporogenesis. In order to provide more information about the mechanism(s) of fertility alternation in TGMS wheat, the relationship between fertility alternation and levels of phytohormones was analyzed by endogenous hormone quantification and exogenous hormone treatments in the present research. Sown at an earlier date with a relatively low temperature and short daylight, TGMS wheat was male sterile phenotypically. Pollen abortion mainly occurred at the mononucleate to bi-nucleate stages of microsporogenesis and pollen abortion was mainly of the spherical type. Levels of endogenous indole-3-acetic acid (IAA), abscisic acid (ABA) and gibberellic acid (GA₃) in the anthers were at lower levels, and zeatin riboside (ZR) was higher. Sown at a later date, when the temperature during the critical period for fertility alternation was relatively high and the daylight was long, TGMS wheat was almost as fertile as the normal genotype and the contents of endogenous IAA, ABA and GA₃ in anthers were at higher levels, and the content of ZR was at a lower level. At the critical period for fertility alternation, treatments with exogenous IAA, ABA, GA₃ or aminoethoxy vinylglycine (AVG), an inhibitor of ethylene biosynthesis, decreased the frequency of sterile pollen grains and increased the frequency of self-pollinated fertile florets. Treatment with exogenous 2-chloroethyl phosphonic acid (CEPA), a releaser of ethylene, increased the frequency of sterile pollen grains and decreased the frequency of self-pollinated fertile florets. It was thus suggested that the fertility alternation of TGMS wheat was closely related to levels of phytohormones in the anthers, and changes of endogenous hormone levels were among the important factors responsible for the fertility alternation of TGMS wheat.     

花粉特异性核糖核酸酶基因诱导籼稻雄性不育及其遗传研究

以水稻愈伤组织和悬浮细胞系作为基因枪转化的外植体,把水稻花粉特异性基因PS1启动子与barnase构成的嵌合基因导入籼稻,获得籼稻五个品种Basmati 1、青油占、胜优2号,明恢63,新山占29的转基因植株.试验以两个质粒PS1- barnase和pILTAB227共转化的方法,以潮霉素B作为筛选因子,选择抗性愈伤及再生植株.获得的barnase转基因植株的育性比未转化的对照明显降低,表现为部分不育和完全不育.除barnase阳性转化株平均株高比对照有所降低外,营养器官发育正常,雌性可育.完全不育的植株花粉粒畸形,不能被I-KI溶液染色,但它们与正常植株杂交能够获得杂交种子.转基因植株的Sonthern杂交分析表明,bamase基因普遍为多拷贝整合.对转基因植株白交及与非转化株测交后代以点杂交分析bamase转基因的遗传行为,发现转基因的遗传符合1～3个插入位点的孟德尔遗传模式.     

Interspecific hybridization between rice bean (Vigna umbellata) and its wild relative (V. minima): Fertility-sterility relationships

Summary The pre-and post-fertilization barriers in the interspecific crosses between Vigna umbellata and V. minima were investigated. In the reciprocal crosses (V. minima as the parent) the entry of pollen tubes into the ovary was delayed by about 4 h, and no seed set was observed. However, no pre-fertilization barriers were encountered in crosses involving V. minima as the parent and V. umbellata as the parent (normal cross). The delay/absence of divisions in the endosperm and the failure of embryo to divide were the post-fertilization barriers responsible for somatoplastic sterility in normal crosses which yielded a few hybrid seeds. The hybrid seeds showed poor germinability. The F₁ hybrids were intermediate between the parents in most morphological characters, and are completely sterile for pollen. Backcrossing of F₁ hybrid with both the parents did not restore fertility in the progenies. V. minima is considered as the tertiary gene pool of the rice bean.     

The transfer of a gene for glutinous endosperm to Oryza glaberrima Steud. From a japonica variety of O. sativa L.

Summary In common rice, Oryza sativa L. (n=12), the gene Am for non-glutinous is dominant over the gene am for glutinous. In African rice, O. glaberrima Steud. (n=12), no spontaneous glutinous strain has been found, but recently a glutinous strain of glaberrima was induced by EMS-treatment.The interspecific cytoplasm substitution line with sativa cytoplasm and glaberrima nucleus is male sterile. It has been confirmed that the complete restoration of pollen fertility in this male sterile line is attributed to a single dominant nuclear gene Rf _j.Trial to transfer gene am from sativa to glaberrima was commenced with backcrosses of the F₁ hybrid (glutinous sativa cv. Iwai-mochi × glaberrima ) to glaberrima type plants of the substitution line homozygous for Rf _j,using the latter as the pollen parent. At the B₁ step, highly fertile glaberrima type Am/am plants were obtained. Thereafter plants of this type were backcrossed to normal glaberrima as the recurrent pollen parent to complete the nuclear substitution. It was confirmed that the EMS-induced glutinous character of glaberrima was a monogenic recessive and that the same gene controls the expression of glutinous character in the different rice species, sativa and glaberrima.     

Cytoplasmic male sterility in quinoa

Summary The quinoa cultivar Apelawa carries both normal and male sterile cytoplasms. Plants with male sterile cytoplasm produce flowers characterized by the complete absence of anthers and prominent exsertion of stigmas. Intraspecific crosses between male sterile quinoa plants and normal male fertile pollen donors consistently produced male sterile offspring under greenhouse conditions. Interspecific hybridization between male sterile quinoa plants and the related weed species Chenopodium berlandieri resulted in offspring with partial restoration of male fertility. The male sterile cytoplasm found in Apelawa has potential for use in the production of quinoa hybrids, although a more complete restorer system than that identified in C. berlandieri would be desirable.     

Inheritance of male sterility mutations induced in haploid sorghum tissue culture

Summary A high frequency of male sterile mutants regeneration was shown in callus cultures derived from leaves and panicles of haploid sorghum (Ms_c1, A1 cytoplasm) and a spontaneous autodiploid obtained from this haploid. The cultures derived from the embryos of this autodiploid yielded significantly fewer mutants. Absolutely or partially male sterile mutants appeared among the regenerants or in the progeny of fertile regenerants. In the self-fertilized progenies of partially male sterile mutants and in the hybrids of sterile mutants with autodiploid line (i.e. under one and the same nuclear genome) male sterility mutations were inherited as cytoplasmic. Non-Mendelian segregation of sterile, partially male sterile and fertile plants was observed in these progenies. Partially male sterile plants were characterized by somatic segregation of male sterility genetic factors. In test-crosses with some CMS A1 fertility restorers, mutations were manifested as nuclear recessive while with others as nuclear dominant. These differences are supposed to be the result of interaction of fertility restorer genes of these testers with the novel cytoplasm. Male sterility mutations accompanied with female sterility were inherited as nuclear recessives.Abbreviations f fertile - ps partially male sterile - s male sterile plants     

一个水稻开颖不育突变体ohs1(t)的遗传分析及基因定位

我们在明恢86的转基因后代中发现了一个水稻花器官发育突变体,暂命名为开颖不育(open hull sterile 1,ohs1(t)))突变体.ohs1(t)突变体表现颖花开裂,内外稃片变细,内稃微弯向外稃,有雌雄蕊分化,但雌雄蕊较野生犁株的小,大多数花药没有花粉,少数花药中含有不育花粉,雌雄配子均不育.突变体ohs1(t)分别与明恢86、R527、93-11和中花16号杂交后代遗传分析表明,ohs1(t)是一个隐性基因控制的突变体.以ohs1(t)和93-11杂交F2群体中突变个体作为初步定位群体,采用已报道的SSR标记将OHS1(t)初步定位在1号染色体的长臂端RM493和RM5638两个标记间.随后利用已公布的水稻基因组序列(http://rgp.dna.affrc.go.jp/E/index.html)及93-11和日本晴间SSR标记数据库(http://www.gramene.org/),新开发和筛选了SSR和InDel标记,并以ohs1(t))和中花16号杂交F2群体中突变个体作为新定位群体,将OHS1(t)基因进一步定位在NSSR0115和InDel0102之间,遗传距离分别为0.2 cM和0.3 cM,物理距离约66 kb.     

Genetics of fertility restoration of ‘Wild Abortive’ cytoplasmic male sterility in rice,Oryza sativa L.

Summary Genetics of fertility restoration in six varieties and breeding lines of rice was studied in Wild Abortive cytoplasmic genetic male sterility system using cytoplasmic male sterile lines V 20 A and IR 54752 A. Fertility evaluation of the plants in F₂ and testcross populations of the crosses of V 20 A with PR 103, PR 106 and PAU 502-94-1, and IR 54752 A with PAU 1124-36-1 and PAU 1126-1-1 revealed that fertility restoration in PR 103, PR 106, PAU 502-94-1, PAU 1124-36-1 and PAU 1126-1-1 was controlled by two independently segregating dominant genes. The two genes appeared to have additive effects; one of them being stronger than the other in imparting fertility restoration. Data on spikelet fertility of the plants in F₂ and testcross populations of V 20 A/UPR 82-1-1 cross showed that fertility restoration in UPR 82-1-1 was controlled by two independently segregating dominant genes which exhibited recessive epistatic interaction.

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Cytological screening of rice TGMS lines

An investigation was undertaken to develop new stable thermo‐sensitive genic male sterility (TGMS) rice lines in intermated progenies (IMPs) of TGMS lines by using an anther clearing technique. The results indicate that both pre‐ and post‐meiotic genetic systems operate during anther development for the expression of sterility in TGMS lines. In all the TGMS lines, sterile anthers were small with empty pollen grains of irregular shape, except for TS 16, which showed pollen‐free anthers. This indicates that the sensitive stage of TS 16 is around stage IV (stamen and pistil primordia) of panicle development. Distinct differences were observed between sterile and fertile phases with respect to anther size, shape and colour of the pollen grains in TS 18 and TS 29. The pollen grains at the sterile phase were small and irregular in shape while in the fertile phase they were plump and larger with a yellow colour, establishing that the occurrence of sterility in TS 18 and TS 29 is post‐meiotic. Three distinct classes of pollen fertility percentage viz. <20%, 50‐70% and >90% were observed in IMPs. Anther clearing in IMPs showed distinct developmental patterns of pollen production with respect to distinct classes of pollen fertility. Less than 20% pollen fertility was observed in hybrids such as TS 15 × TS 16, TS 15 × Co 47, TS 18 × TS 16 and TS 18 × Co 47 which hold promise for developing new TGMS lines with a good plant type and acceptable quality.     

N2O induces mitotic polyploidization in anther somatic cells and restores fertility in sterile interspecific hybrid lilies

Fertile plants undergoing male gametogenesis can be treated with nitrous oxide (N₂O) gas to obtain 2n male gametes. N₂O treatment is also expected to restore the fertility of interspecific hybrids through meiotic restitution or mitotic amphidiploidization. However, this technique has few applications to date, and it is un-known how N₂O treatment restores fertility in sterile hybrids. To establish optimal N₂O treatment conditions and determine its cytological mechanism of action, we treated various sized floral buds with N₂O gas at different anther developmental stages from fertile and sterile hybrid lilies. N₂O treatment using the optimal 1–4 mm floral buds induced mitotic polyploidization of male archesporial cells to produce 2n pollen in fertile hybrid lilies. In sterile hybrid lilies, N₂O treatment doubled the chromosome number in male archesporial cells followed by homologous chromosome pairing and normal meiosis in pollen mother cells (PMC), resulting in restoration of pollen fertility. Backcrossing the resultant fertile pollen to Lilium × formolongi produced many triploid BC₁ plants. Thus N₂O treatment at the archesporial cell proliferating stage effectively overcame pollen sterility in hybrid lilies, resulting in fertile, 2n pollen grains that could produce progeny. The procedure presented here will promote interspecific or interploidy hybridization of lilies.