Genetic male sterility in the pea (Pisum sativum L.)

Summary Genetic male sterility has been described in the pea (Pisum sativum L.), but no comprehensive effort has been made to study the phenomenon. A preceding companion paper reported the inheritance, allelism and linkage relations of thirteen male sterile mutants obtained from seed mutagen treatments. In the present study, the same male sterile mutants were investigated cytologically to determine the cause of sterility. Normal microsporogenesis and microgametogenesis was compared to that of the mutants. The ms-2, ms-3, and ms-4 mutants exhibited meiotic abnormalities similar to those described by Gottschalk and colleagues except that ms-3 had a high degree of female sterility. Chromosome clumping and spindle abnormalities leading to formation of coenocytic microspores and degeneration were characteristic of ms-2 and ms-4. The ms-2 and ms-4 mutants were previously found to be allelic, and were nearly identical cytologically in the present study. The ms-3 mutant exhibited a lack of chromosome condensation in meiosis I, and a lack of spindle formation in both meiotic divisions. Two mutations (ms-6 and ms-10) affected meiosis, with univalents at metaphase, and asynchronous divisions during meiosis II. Microspores of ms-6 completely degenerated whereas those of ms-10 showed some development. Sticky chromosomes, bridges and fragments, tripolar spindles, and lack of a second division were characteristic of ms-10. The ms-10 mutant also showed reduced female fertility. Two male steriles (ms-5 and ms-9) had abnormalities associated with premature degeneration of the tapetum. Three others (ms-7, ms-8, and ms-11) aborted pollen during meicrogametogenesis. Pollen grains of ms-11 had thinner walls than normal and lacked sculptured exine. The ms-10 mutant, and those affecting microgametogenesis (ms-5, ms-7, ms-8, ms-9, and ms-11) produced some stainable and viable pollen.     

An ms2 male-sterile, female-fertile soybean sharing phenotypic expression with other ms mutants

Genetic and cytological studies of microsporogenesis and microgametogenesis were conducted with a natural male‐sterile, female‐fertile soybean mutant (BR97‐17971) found in an F₄ breeding line of the Brazilian soybean breeding programme. Allele tests with ms Type Collection from USDA/ARS showed that the gene was allelic to ms2. Conventional analysis of microsporogenesis revealed a differential meiotic behaviour from the normal one reported in ms2 male‐sterile plants. Sterile plants have different levels of meiotic abnormalities related to chromosome segregation. Despite segregational abnormalities in the first and second divisions leading to micronuclei formation, the main meiotic cause of pollen sterility was absent or the defective cytokinesis following telophase II. Absent or defective cytokinesis has never been reported in ms2 mutants, but it was reported in the ms1 and ms4 mutants. After telophase II, one to four nucleate microspores underwent degeneration. Cross‐sections of sterile plant anthers showed that, at telophase II, the tapetal cells with large vacuoles degenerated. Despite callose deposition around meiocytes, sterile plants did not form tetrads. They degenerated and collapsed after callose dissolution, forming an amorphous mass. Anthers from male‐sterile plants were shrivelled.     

Pleiotropic effects of male sterility genes in hybrid tomatoes (Lycopersicon esculentum Mill.)

Summary The influence of seven recessive male-sterile alleles on early marketable yield, total marketable yield and average fruit weight in heterozygous F1 hybrid tomatoes was studied. Differences were found between nearisogenic F1 hybrid pairs, in the mutants ms-14, ms-17 and ms-18 for percentage of early marketable yield; in the mutants ms-17, ms-31 and ms-47 for average fruit weight; and in the mutants ms-14, ms-17 and ms-33 for total marketable yield. These differences may be attributed to pleiotropic effects of male-sterility alleles or genes highly linked to these alleles. The direction and the magnitude of the pleiotropic effect on a specific characteristic were found to be dependent on the general genetic background of the parental lines and the specific combining ability of the F1 hybrid. Interactions found in crosses between male-sterile and male-fertile female lines and parental lines suggest that male-sterility alleles affect the general combining ability of female lines. Such differences were demonstrated to be statistically significant for percentage of early marketable yield with mutant ms-18, for average fruit weight with mutants ms-47, and for total marketable yield with mutant ms-17 and ms-33. The absence of uniformity with respect to the pleiotropic effects and occasional deviations in the general combining ability are discussed.     

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.     

Tapetal behaviour, gene action and breeding value in male-sterile peas

Eight non-allelic male-sterile mutants controlled by a single recessive gene were induced in garden pea (Pisum sativum) after EMS, DES and gamma-ray-mutagen treatments singly and in combination. These mutants differ in the time and type of tapetal development due to differential action of male-sterile (ms) genes over the sporogenous and non-sporogenous anther tissue. In the msg1 mutant, the sporogenous tissue breaks down during premeiosis, followed by tapetal degeneration. In msg2, sporogenous tissue and tapetal tissue exhibit anomalies at early and late prophase 1, respectively. Although in msg3 and msg5 the ms gene action over sporogenous tissue initiates during early and late prophase, respectively, the tapetal tissue breaks down during post-meiosis. In msg6, anomalies in the sporogenous tissue appear during prophase II, but the tapetum degenerates during the mononucleate stage. Although both the tapetal and sporogenous tissue anomalies appear simultaneously at pachytene in msg4, the tapetal breakdown is delayed until the microspore stage. In msg7 and msg8, anomalies in both these tissues occur simultaneously during the tetrad and post-meiotic stages, respectively. Despite differences in the timing of tapetal and sporogenous tissue breakdown, tapetal development is normal in msg1, msg5, msg6, msg7 and nisg8 but abnormal in msg2, msg3 and msg4. The ms gene action is dual in msg2, msg3 and msg4 but single in msg1, msg5, msg6, msg7 and msg8. In all these mutants, the time of tapetal anomaly exhibits no correlation with the time of ms gene action. The gene for open flower found in one male-sterile mutant needs to be introduced into fertile peas for commercial hybrid-pea breeding.     

Genetics of thermosensitive genic male sterility in rice

Summary Inheritance of thermosensitive genic male sterility (TGMS) in Norin PL12 and IR32364TGMS and their allelic relationship were studied from F₁, F₂ testcross (TC) and F₃ generations of the crosses made with the two mutants and several fertile tester parents. F₂, TC and F₃ segregation behavior for pollen and spikelet fertility indicated that the TGMS trait in the two mutants was controlled by a single recessive gene. Allelic relationship studies indicated that TGMS genes of the two mutants were different. Since TGMS gene in Norin PL12 has been designated as tms ₂ , the TGMS gene present in IR32364TGMS is tentatively designated as tms ₃ (t) until allelic test is done with another TGMS gene (tms ₁ ) reported from China in a line 5460S seeds of which were not available.     

Development of a cytoplasmic-nuclear male-sterile line of soybean

The F₁ of N8855 x N2899, a cross between two cultivars of G. max (L.) Merr., was found to be male-sterile. After it was back-crossed with the recurrent parent N2899 for four successive generations, a cytoplasmic-nuclear male-sterile line and its maintainer line, designated as NJCMS1A and NJCMS1B, respectively, were obtained. NJCMS1A was stable in male sterility with 98.29% plants being male-sterile at 0% pollen germination, while its female fertility was normal. The pollen abortion of NJCMS1A occurred at the binucleate stage. Then the vacuolation and disintegration of cytoplasm became further pronounced in NJCMS1A pollen. In addition, the abnormal phenomenon of 2 ∼ 3 styles surrounded by 20 ∼ 30 stamens was found in a few flowers of some male-sterile plants at BC₁F₁ and BC₂F₁. This revised version was published online in August 2006 with corrections to the Cover Date.     

Allelic relationship between spontaneous and induced mutant genes for stem fasciation in chickpea

Stem fasciation is a morphological abnormality observed in plants where the stem is widened and leaves and flowers or pods are clustered at the apex. Several spontaneous mutants and one induced mutant for stem fasciation are found in chickpea (Cicer arietinum L.). This study was aimed at determining allelic relationship between spontaneous and induced mutant genes controlling stem fasciation and effects of stem fasciation on grain yield. Two spontaneous (ICC 2042 and ICC 5645) and one induced (JGM 2) stem fasciation mutants were crossed in all combinations, excluding reciprocals. The F₁ and F₂ plants from a cross between the two spontaneous mutants had fasciated stem. This indicated the presence of a common gene (designated fas1) for stem fasciation in the two spontaneous mutants. The F₁s of the crosses of the induced mutant JGM 2 with both spontaneous mutants had normal plants and segregated in a ratio of 9 normal : 7 fasciated plants in F₂. Thus, the gene for stem fasciation in the induced mutant JGM 2 (designated fas2) is not allelic to the common gene for stem fasciation in spontaneous mutants. The two genes in dominant condition produced normal non‐fasciated stem. The fasciated and the non‐fasciated F₂ plants did not differ significantly for number of pods per plant, number of seeds per plant, grain yield per plant and seed size, suggesting that it is possible to exploit the fasciated trait in chickpea breeding without compromising on yield.     

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.     

An induced brachytic mutant of chickpea and its possible use in ideotype breeding

Mutations were induced in chickpea (Cicer arietinum L.) cultivar ‘JG 315’ through treatment of seeds with ethyl methane sulphonate (EMS). One of the mutants, named JGM 1, had brachytic growth (compact growth), characterized by erect growth habit, thick and sturdy stem, short internodal and interleaflet distances and few tertiary and later order branches. It was isolated from M₂ derived from seeds treated with 0.6% EMS for 6 h. Segregation analyses in F₂ progenies of its crosses with normal chickpea genotypes (JG 315, ICC 4929, and ICC 10301) suggested that a single recessive gene controlled brachytic growth in JGM 1. This gene was not allelic to the br gene for brachytic growth in spontaneous brachytic mutant E100YM. Thus, the gene for brachytic growth in JGM 1 was designated br2 and the br gene of E100YM was redesignated br1. Efforts are being made to use JGM 1 in development of a plant type with short internodes and erect growth habit. Such plant type may resist excessive vegetative growth in high input (irrigation and fertility) conditions and accommodate more plants per unit area.     

Pollination systems, hybridization barriers and meiotic chromosome behaviour in Nemesia hybrids

The ability of 13 Nemesia species (six annual and seven perennial) to sexually hybridize was investigated. Six of the perennial Nemesia species investigated were inter-fertile with one another. Two of the annual species, N. macroceras and N. strumosa, were inter-fertile. Thirty three crosses were successful and resulted in viable seeds. The analysis of meiotic chromosome behaviour in interspecific hybrids indicated that Nemesia chromosomes in different parental species were homeologous. No evidence of chromosome inversions or chromosome translocations was observed during meiosis in interspecific hybrids between the six perennial Nemesia species. In the hybrids produced between N. macroceras and N. strumosa, a quadrivalent was observed during meiotic metaphase I, indicating that these two species differ by a reciprocal translocation. A successful hybridization was made between N. anisocarpa (annual) and N. foetans (perennial), producing two triploid hybrids. In the unsuccessful crosses, pollen tubes were observed entering ovaries and ovules, suggesting that post-fertilization barriers were preventing sexual hybridization. Many of these crosses produced nonviable, shrunken, empty seeds, suggesting that endosperm breakdown and embryo abortion prevent interspecific hybridization in unsuccessful crosses. The manipulation of ploidy levels in N. fruticans and N. strumosa and tissue culture of N. strumosa × N. fruticans ovules failed to overcome post-fertilization barriers between these species.     

抗丝黑穗病、抗败育高粱A2细胞质雄性不育系A2Sx3197的选育

A₁Tx3197曾经是我国广泛应用的高粱细胞质雄性不育系,20世纪70年代末,由于高粱丝黑穗病病菌生理小种分化,该不育系以及用其配制的杂交种逐渐失去了对高粱丝黑穗病菌的抗性。同时该不育系小花败育日渐严重,制种产量极低,甚至造成绝收。为了改良A₁Tx3197的抗病性及抗败育性,本研究利用A₂保持系在A₁位点含有A₁育性恢复基因MS₁MS₁和在A₁细胞质背景下表现恢复的特点,以不育系A₁Tx3197为轮回亲本,以含有抗丝黑穗病、抗败育基因的BV₄为供体,通过杂交和多代回交,得到含有双抗基因的A₂类型细胞质雄性不育的保持系BSx3197(MS₁ms₁ms₂ms₂),在该材料自交的同时,用其对A₂细胞质雄性不育系进行细胞核代换,经过多代回交和自交,最终育成了抗丝黑穗病、抗败育的A₂细胞质雄性不育系A₂Sx3197和保持系BSx3197(MS₁MS₁ms₂ms₂)。结果表明,新选育的不育系A₂Sx3197在A₁和A₅细胞质背景下表现恢复,在A₂、A₃、A₄、A₆和9E细胞质背景下表现不育,丝黑穗平均发病率为0~0.8%,败育率为0~8.4%,抗丝黑穗病性、抗败育性明显优于被改良不育系,接近或达到抗原供体BV₄水平;而在抽穗期、株高、穗长、穗宽、千粒重、穗粒重、粒色、壳色、穗形、穗型等主要性状方面与A₁Tx3197差异不显著。     

Inheritance of morphological traits of periwinkle mutants with modified contents and yields of leaf and root alkaloids

Periwinkle Catharanthus roseus is a medicinally important plant producing anticancer and antihypertension alkaloids. Two mutants, one dwarf and one semidwarf and both, with a high alkaloid content in the roots and one mutant with a wavy leaf margin and a high alkaloid content in its leaves were obtained after induced chemical mutagenesis with ethyl methane sulphonate and N-nitroso-N-ethylurea in the variety ‘Nirmal’, which is resistant to dieback disease. These mutants were evaluated in the M₃ and M₄ generations. The dwarf and semidwarf mutants differed from the parental variety for many morphological characters, while the mutant with the wavy leaf margin differed mainly in leaf size and leaf thickness. Although both dwarf and semidwarf mutants showed a significantly higher alkaloid content in their roots in both generations, only the semidwarf mutant gave a significantly higher (23%) root alkaloid yield than the parental variety. The mutant with the wavy leaf margin showed a significantly higher alkaloid content in the leaves in both the M₃ and M₄ generations and also had a significantly higher (21%) leaf alkaloid yield than the parental variety. All three mutants were found to be controlled by monogenic recessive genes; the genes for ‘dwarfness’ and ‘semidwarfness’ were allelic to each other, with the allele for semidwarfness being dominant over the allele for dwarfness. The gene for the wavy leaf margin was inherited independently of the genes for dwarfness and semidwarfness.     

Effects of Temperature on Pollen Tube Growth and Fruit Set in Reciprocal Crosses Between Cucumis sativus and C. metuliferus

Interspecific hybridization between Cucumis sativus and C. metuliferus may be used to introduce disease resistance into the cultivated cucumber. Hybrid plant development, however, is restricted by strong barriers to crossing. The present study was undertaken to examine temperature effects on pollen tube growth and fruit set in reciprocal crosses between C. sativus and C. metuliferus. When crossing C. sativus×C. metuliferus, at 20°C, pollen tube growth was arrested in the stylar region of the pistil and no fruits containing embryos were found. However, at 23° and 26°C, C. metuliferus pollen tubes penetrated into the C. sativus ovules. The enhanced pollen tube penetration was correlated with improved embryo development. Although pre-fertilization barriers were overcome, post-fertilization barriers caused abortion of hybrid embryo development at the globular stage. No effects of higher temperatures were found in the cross C. metuliferus×C. sativus; Pollen tubes were generally arrested in the stylar region of the pistil.     

甘蓝型油菜隐性核不育系20118A的育性遗传及分子标记辅助选择

以20118A不育系和临保系与22个油菜品种(系)杂交测交后代为材料, 采用经典遗传学和分子标记辅助选择方法, 验证该不育系统遗传控制体系及等位基因分布频率; 探索利用连锁共显性标记筛选两型系和临保系基因型的高效性和准确率。研究表明, 6个品种(系)与20118A测交产生的F₂世代, 所有组合可育株∶不育株均符合3∶1或13∶3分离规律, 而与20118A-TAM杂交产生的6个F₂中1个呈13∶3分离, 其余均为全可育, 育性符合1对隐性不育基因和1对隐性上位抑制基因互作控制的遗传模式; 进而采取反向验证方法, 从1 059个F₂分离单株中, 用新发展的Bnms₃/Bnrf连锁共显性标记跟踪选择, 直接获得临保系(ms₃ms₃rfrf)、纯合不育株(ms₃ms₃RfRf)和两型系可育株(Ms₃ms₃RfRf) 70、69和135株, 经测交或互交验证, 准确率均达95%以上; 根据20个测交品种的后代分离, BnRf位点上只出现Rf和rf两个等位基因, 推测第3个等位基因存在的频率很低, 基本可以根据两基因各2等位基因互作原理开展分子标记辅助育种。     

A new gene controlling hybrid sterility between Oryza sativa and Oryza longistaminata

Oryza longistaminata is an excellent gene pool to improve Asian cultivated rice Oryza sativa. However, hybrid sterility between O. longistaminata and O. sativa hinders application of desirable genes in rice production. In order to further understand the nature of interspecific hybrid sterility between these two species, near isogenic lines (NILs) were raised with RD23, an indica cultivar from Thailand, as background and an accession of O. longistaminata as donor. Using two NIL/RD23 F₂ populations, a new pollen sterility gene, denoted as HYBRID STERILITY 44(t) or S44(t) in abbreviation, was mapped between simple sequence repeat markers RM5814 and RM20695 on the long arm of rice chromosome 6. The genetic pattern of S44(t) follows one-locus allelic interaction model. The interaction between S44(t)-sativa and S44(t)-longistaminata leads to partial abortion of male gametes carrying the allele of S44(t)-sativa in the heterozygotes, but the spikelet fertility is not affected by S44(t).     

Statistical discrimination between pollen tube growth and seed set in establishing self incompatibility in Gaura lindheimeri 1

The University of Minnesota Gaura breeding program is developing USDA Z3-4 winter-hardy genotypes via interspecific hybridization of G. lindheimeri (Z5-6) and G. coccinea (Z2-4). Prior to commencing interspecific hybridization, the reproductive barriers operating in both parental species need to be characterized. The objective of this research was to determine the type and stability of reproductive barriers operating in G. lindheimeri by statistical comparisons between pollen tube growth and seed set in a full-sib diallel. Slowed or aborted pollen tube growth in the style indicated the presence of a gametophytic self incompatibility (SI) system. A statistical method, female (FCC) and male (MCC) coefficients of crossability, was used to verify that a stable SI system was operating and that other reproductive barriers were present. Several genotypes also expressed stage-specific inbreeding depression and incongruity. The simple linear regression equation for FCC/MCC, using pollen tube growth, was Y = 0.0124 + 0.974X, which was much closer to the expected Y = 0.0 + 1.0X (indicating a stable SI system) than the equation for seed set, Y = 0.012 + 0.910X. Using pollen tube length, both general combining ability (GCA) and specific combining ability (SCA) values were highly significant for G. lindheimeri (P ≤ 0.001). Histograms were used to delineate cut-offs to identify intra-incompatible/inter-compatible classes and S allele groups. Four possible classes were identified, but further research is needed to verify S allele genotypes.Scientific Research Paper No. 031210120 of the Department of Horticultural Science. This research was supported by a grant from the Perennial Plant Association and, in part, by the Minnesota Agricultural Experiment Station     

Investigation of the mode of action of the X locus in tomato

Summary The mode of action of the X locus in tomato was investigated. The X is a microgametophytic factor which operates only in X x. In X x, the X causes the abortion of microgametophytes carrying x. On account of this, X x gives rise to 50% pollen abortion. The segregation of hl which is linked with x at a distance of 18 units was also studied. hl x/Hl X causes 50% pollen abortion and aberrant segregation of hl, indicating that the microgametophytes which are aborted are those carrying x. hl X/Hl X results in low pollen abortion and normal 3:1 segregation of hl indicating that X does not operate in the homozygotes of X.     

Cytoplasmic male sterility in barley. III. Maintenance of sterility and restoration of fertility in the msml cytoplasm

Summary 58 varieties, strains or mutants of barley were tested in the msml cytoplasm in Finland, location ca. 61 N. Three (5%) were found to be partial restorers, the rest being maintainers of sterility. 31 Israeli strains of wild barley (ssp. spontaneum) were tested. About one third were maintainers of sterility, the majority partial restorers, and two strains were full restorers. There is probably polymorphism of the restorer gene in Israeli wild barley. Partial restoration displays an environmental response. The physiology of partial restoration is discussed.     

水稻60Co γ辐照诱变雄性不育突变体的败育特征与遗传分析

用406.8 Gy60Coγ辐照诱变水稻品系08-208+7的干种子,从M3代中获得3株雄性不育突变株ms1、ms2和ms3。对其小孢子败育的细胞学观察表明,ms1为典败型,其败育时期为单核至双核期;ms2和ms3表现为无花粉型,败育时期为减数分裂二分体至四分体时期。遗传研究表明,各类型均为单基因隐性遗传;ms1分别与ms2、ms3相互不等位,ms2与ms3之间相互等位。