Chromosomal location of fertility restoring genes for ‘wild abortive’ cytoplasmic male sterility using primary trisomics in rice

Summary Identification and location of fertility restoring genes facilitates their deployment in a hybrid breeding program involving cytoplasmic male sterility (CMS) system. The study aimed to locate fertility restorer genes of CMSWA system on specific chromosomes of rice using primary trisomics of IR36 (restorer), CMS (IR58025A) and maintainer (IR58025B) lines. Primary trisomic series (Triplo 1 to 12) was crossed as maternal parent with the maintainer line IR58025B. The selected trisomic and disomic F₁ plants were testcrossed as male parents with the CMS line IR58025A. Plants in testcross families derived from disomic F₁ plants (Group I crosses) were all diploid; however, in the testcross families derived from trisomic F₁ plants (Group II crosses), some trisomic plants were observed. Diploid plants in all testcross families were analyzed for pollen fertility using 1% IKI stain. All testeross families from Group I crosses segregated in the ratio of 2 fertile: 1 partially fertile+partially sterile: 1 sterile plants indicating that fertility restoration was controlled by two independent dominant genes: one of the genes was stronger than the other. Testcross families from Group II crosses segregated in 2 fertile: 1 partially fertile+ partially sterile: 1 sterile plants in crosses involving Triplo 1, 4, 5, 6, 8, 9, 11 and 12, but families involving triplo 7 and triplo 10 showed significantly higher X² values, indicating that the two fertility restorer genes were located on chromosome 7 and 10. Stronger restorer gene (Rf-WA-1) was located on chromosome 7 and weaker restorer gene (Rf-WA-2) was located on chromosome 10. These findings should facilitate tagging of these genes with molecular markers with the ultimate aim to practice marker-aided selection for fertility restoration ability.     

Application of C-banding and fluorescence in situ hybridization for the identification of the trisomics of Hordeum chilense

Hordeum chilense is a wild barley species that has a high degree of genetic variability and significant potential for use in plant breeding. To establish a series of trisomics in H. chilense (2n = 14), plants with 2n + 1 chromosome numbers were isolated from the progenies of selfed triploid plants. Based on both fluorescent in situ hybridization with pAs1 and pTa71 repetitive DNA probes and C-banding patterns, seven different trisomics were tentatively identified. Primary trisomic plants were for chromosomes 1H^ch, 4H^ch, 5H^ch, 6H^ch and 7H^ch. A secondary trisomic carrying a 5H^chS-5H^chS isochromosome as the extra chromosome and a trisomic for chromosome 3H^ch heterozygous for the 3H^chS-4H^chL and 4H^chS–3H^chL interchange were identified. The trisomic for chromosome 1H^ch cannot be phenotypically distinguished from the diploid. The rest of the trisomic types were distinguishable from the diploid by their morphological characteristics (relatively poor vigour, decreased size and shorter spikes) but they were morphologically indistinguishable from each other. The frequencies of trisomics among the progenies derived from self-fertilization of these aneuploids ranged from 10.7% to 37.5%, with an average frequency of 26.1%. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigations on the breeding behaviour of aneuploids of guava

Summary The breeding behaviour of aneuploids of guava (Psidium guajava L.) such as trisomic, tetrasomic, and higher aneuploids has been studied. Reciprocal crosses between aneuploids and diploids indicated less than 100% crossability. The aneuploids when used as male parents crossed less frequently than as female parents and certain aneuploids crossed more readily than others. Differences were observed in fruit size, fruit weight, and seed number in the reciprocal crosses.The extra chromosome was found to be transmitted through both the egg cell and the pollen. However, the frequency of transmission was greater through the egg cell than the pollen. As high as 26% transmission of extra chromosomes were obtained through the egg cell. There was no clear cut difference between trisomics and higher aneuploids with regard to the frequency of transmission of extra chromosomes.     

Identification of primary trisomics and other aneuploids in foxtail millet

A complete set of nine primary trisomics (2n+ 1) for cv.‘Yugu No. 1’of foxtail millet, Setaria italica (L.) Beauv. (2n= 2x= 18), was identified cytologically from progenies derived from crosses between autotriploids(2n= 2x= 27) and their diploid counterparts. Five autotriploid plants were identified from 2100 seedlings derived from 4x-2x crosses; the reciprocal crosses (2x-4x) failed to produce autotriploids. Autotriploids grew vigorously and were morphologically very similar to diploids. Theprimary trisomics (2n= 2x= 19) constituted ?32.5% of the total progeny from the 3x-2x crosses, whereas 59.8% of the descendants were aneuploids with chromosome numbers ranging from 20 (double trisomics and tetrasomics) to 37 (2n= 4x+ 1; or autotetraploid with one additional chromosome). The nine primary trisomics identified were self-fertile; seven had characteristic morphology, whereas trisomics VIII and IX resembled the disomics. The seed set for trisomic V was the lowest (20%), and trisomic VIII the highest (74%). Other aneuploids with 20 or more somatic chromosomes were either self-sterile or partially fertile with various, but low, levels of seed set. Each of the primary trisomics showed its unique transmission rate when self-pollinated; trisomic IX had the highest (45.8%), whereas trisomic V had the lowest (19.6%) transmission rate.     

Inheritance and chromosome location of Alp, a gene controlling aluminum tolerance in 'Dayton' barley

Aluminum (Al) toxicity is a major limiting factor in acid soils and more adequate genetic tolerance is needed to improve barley adaptation and production in affected regions. To study the inheritance and chromosome location of the Alp gene controlling Al tolerance in ‘Dayton’ barley the primary trisomics of sensitive ‘Shin Ebisu 16’ were crossed to ‘Dayton’. Parental, F₁ and F₂ seedlings were grown in nutrient solution containing 0.03, 0.06 and 0.09mM Al. and classified for tolerance by haematoxylin staining of the roots. In diploid F₂ progeny, Alp was inherited as a single gene, dominant at 0.06mM and recessive at 0.09 mM concentrations, as indicated by the 3:1 and 1:3 (tolerant: sensitive) segregation ratios, respectively. Segregation of the trisomic Frderived F₂ seedlings at 0.06mM Al deviated significantly from the 3:1 only for the triplo 4/‘Dayton’ cross. Data for this cross fit the expected trisomic ratios, indicating that the Alp gene is distally located from the centromere on chromosome 4. These results confirm that tolerance is simply inherited, but expression of tolerance is dependent on Al concentration and allele dose.     

Fertility,plant morphology,and transmission rates of the extra chromosome in single and double trisomics of Solanum tuberosum L. Group Tuberosum

Summary Initial single and double trisomics of S. tuberosum Group Tuberosum cv. Gineke were successfully crossed with and backcrossed to clones obtained through inbreeding of self-compatible dihaploids of the same variety. Some trisomics showed reduced flowering or flower abnormalities and contributed therefore only to a small extent. Berry-set and seed-set varied considerably. There was no relation between these phenomena, nor was there any relation between either berry-or seed-set and the identity of the extra chromosome in the female parent. Seed-set seemed to be influenced by the male parent. When a more inbred male parent was used in the crosses with trisomics this often resulted in less seed per cross. There was no clear relation between seed-set and stainability of the pollen grains, but both the strong selection for good pollen and the high level of self-compatibility, have apparently contributed to the success of the crosses. The double trisomic plants yielded less seed than most single trisomics. Only three of the single trisomics produced stainable pollen and two of them yielded progeny when used as male parent in crosses or selfings.In the progenies several of the trisomic types could be distinguished on the basis of plant morphology in the young seedling stage. For ten different trisomics the morphotype is being described. The average rate of female transmission of the extra chromosome was about twenty per cent, but there was a wide variation, both between and within the various trisomic types. The results indicated that for chromosomes 3 and 8 the rate of transmission was higher than the average value. In one out of two trisomic types male transmission of the extra chromosome occurred, with a rate of 4.7%. The possible causes for the observed differences in female transmission of the extra chromosome are being discussed.     

Transfer of cytoplasmic male sterility by spontaneous androgenesis in tobacco (Nicotiana tabacum L.)

Summary Five cytoplasmic male sterile lines of Nicotiana tabacum homozygous for a dominant rootless mutation [Rac^-] were used as female parents in crosses with three male fertile varieties. Androgenetic haploids were selected by their ability to form plantlets with a normal root system, whereas hybrid plantlets failed to grow. High frequencies of androgenetic haploid plants were obtained with N. debneyi cytoplasm, and with one paternal genotype. Chromosome doubling was performed using three different methods (pollination, in vitro culture, acenaphthen) and cytoplasmic male sterile doubled haploid plants have been obtained. The results demonstrate the efficiency of this method for a rapid cytoplasm transfer in Nicotiana tabacum; the integrity of the cytoplasm is conserved. For the first time, we possess a counter selectable marker universally usable for Nicotiana tabacum and closely related species.     

Trisomic analysis of new gene for late heading in rice, Oryza sativa L

A near isogenic line, T65-LH7 bred from a rice variety, Ketan Nangka by five times of successive backcrossing with Taichung 65 (T65) as recurrent parent was found to carry a recessive lateness gene tentatively designated as ef6(t). The present study was performed to investigate the allelic relationships between ef6(t) and other heading time genes, Ef1, Efx, ef2(t), ef3(t), ef4(t) and ef5 by allelism test and to locate the chromosomal location of ef6(t) by trisomic analysis. In allelism test, six testers carrying each of heading time genes, Ef1, Efx, ef2(t), ef3(t), ef4(t) and ef5 were used. Those testers were the near isogenic lines of T65. T65-LH7 was crossed with respective testers. Heading times in F₂ and/or B₁F₁ plants were examined. All F₂ and/or B₁F₁ populations derived from those crosses exhibited digenic segregations, respectively. These results suggested that ef6(t) was independent of Ef1, Efx, ef2(t), ef3(t), ef4(t) and ef5. Sub sequently, trisomic analysis of ef6(t) was performed using seven Triplo lines having extra chromosomes, 2, 4, 5, 7, 9, 10 and 12. These Triplo lines were the near isogenic lines of T65. They were used as maternal parent to cross with T65-LH7. Heading times in F₂ plants obtained from self-pollination of F₁ plants were observed. Among F₂ plants examined only those derived from a cross between Triplo-7 and T65-LH7 showed a typical trisomic segregation manner, suggesting that ef6(t) was located on chromosome 7. Consequently, the nomenclature of the present gene should be designated as ef6.     

Inheritance of dwarfism in plantain (Musa spp., AAB group)

Plantain (Musa spp., AAB group) is a major food crop in the humid lowland tropics of Africa, the Caribbean and Latin America. Lodging, caused by strong winds occurs periodically in these areas. Therefore, development of dwarf plantain cultivars and elucidation of the inheritance of dwarfism is desirable. A heterozygous normal plantain cultivar (2n= 2x) with long false-internodes (19.4 ± 0.9 cm) was crossed with a homozygous wild banana (2n= 2x) with short false-internodes (6.9 ± 0.4 cm) to develop a test-cross segregating population. A total of 74 euploids (2x, 3x and 4x) were produced. Forty-one normal and 24 dwarf diploids were obtained, which fits a 2: 1 trisomic test-cross segregation ratio for one locus. Dwarfism is controlled by a single recessive gene, dw. At the tetraploid level, two normal and six dwarf hybrids were produced, suggesting that the dw locus is close to the centromere and that there is a dosage effect of the dw allele at the tetraploid level.     

Tertiary trisomics in lentil

Summary Tertiary trisomics have been selected among derivatives of hybrids between the cultivated lentil and its wild progenitor Lens orientalis, and between the cultivated species and L. ervoides. Hybrids heterozygotes to a single translocation were more useful as a source of trisomic plants then those heterozygotes to a number of translocations. The trisomic plants were weeker compared to the euploid plants and many have not reached maturity. The meiosis, fertility and transmission rate of the extra chromosome were studied in a single trisomic line.     

谷子几种农艺性状基因染色体定位及连锁关系的初步研究

利用三体分析法进行谷子染色体基因定位。以豫谷1号三体1-7、四体8和四体9为母本,显性矮秆、法谷56-81、马青苗为父本,配置组合分别进行显性矮秆基因、白米基因和青米基因染色体定位。根据三体1-7植株形态特征和父本标志性状鉴定各自的杂种F₁,采用细胞学方法,通过检查植株根尖染色体数来鉴定杂种F₁的三体8和三体９。经调查和分析各种三体杂种F₂性状分离情况,把显性矮秆基因定位在3号染色体,白米基因定位在4号染色体,青米基因定位在6号染色体。对不同区域的9个青米品种等位检测表明,这些青米基因都是等位基因。以两点测验法,配置组合1066A×法谷56-81和1066A×马青苗进行基因连锁分析。结果,4号染色体上糯性胚乳基因与白米基因间的交换值为（28.9±4.4）cM;6号染色体上1066A不育基因与青米基因间的交换值为（23.2±1.8）cM。     

Identification and Inheritance of Fertility Restorer Genes for 'tour' CMS in Rapeseed (Brassica napus L.)

Eighteen genotypes of Brassica napus were crossed to a cytoplasmic male sterile (CMS) line of B. napus BO 15 carrying B. tournefortii cytoplasm (‘tour’ cytoplasm). Fourteen genotypes were found to be stable maintainers of the ‘tour’ CMS. Of the remaining four genotypes, GSL-1 and ‘Asahi-natane’ were found to be heterozygous and ‘Mangun’ and ‘Yudal’ were homozygous for the restorer gene. Analysis of the F₁ and F₂ progenies of (CMS) BO 15 בMangun’ and (CMS) BO 15 בYudal’ showed that fertility restoration is controlled by a single dominant gene. The availability of a number of stable maintainer lines and the simple inheritance pattern of fertility restorer gene makes ‘tour’ CMS a useful system for hybrid seed production in rapeseed.     

The identification of faba bean (Vicia faba L.) trisomics by translocation tester set

Summary Five subtelocentric primary trisomics of Vicia faba L. were isolated from crosses between asynaptic mutants and normal plants or translocation tester stocks. The extra chromosome of each trisomic was identified cytologically by critical multivalent association at metaphase I of meiosis.     

Relationship between tolerance and resistance to pepper mottle virus in a cross between Capsicum annuum L. × Capsicum chinense Jacq.

Summary Progenies of a cross between pepper cultivar Delray Bell (Capsicum annuum L.) tolerant to pepper mottle virus (PeMoV) and P.I. 159236 (Capsicum chinense Jacq.), resistant to PeMoV were evaluated in greenhouse experiments. The F₁ generation was susceptible to PeMoV, whereas the backeross generations to both parents and the F₂ segregated in a ratio of 1:1. This indicates that PeMoV resistance is controlled at the same locus in both parents or at two closely linked loci. Each parent is homozygous for one locus and the homozygous condition of either allele results in failure to support virus; in heterozygous condition as observed in the F₁ generation, the effect of a single allele is insufficient even when one allele of each type is present, resulting in systemic infection.The abstract of this paper was presented at the IVth Eucarpia Capsicum meetings held in October at Wageningen, Netherlands.Florida Agricultural Experiment Stations Journal Series Paper No. 3175.     

Hybrid necrosis and hybrid chlorosis in Indian varieties of Triticum dicoccum Schubl.

Summary Forty-four varieties of Triticum dicoccum ex India were crossed to two T. aestivum testers, namely, C 306 (Ne ₁ ne ₂ ch ₁ Ch ₂) and Sonalika (ne ₁ Ne ₂ ch ₁ Ch ₂), to determine their necrosis and chlorosis genes. Thirty-six (81%) varieties were found to be carriers of the Ch ₁gene; the genotype of their necrosis gene (Ne ₁or ne ₁) could not be determined for want of suitable testers with the authors. Six varieties were found to be noncarriers for necrosis and chlorosis genes and two varieties were found to be carriers of the Ne ₁gene and non-carriers for the chlorosis gene. Allelic variation at the Ch ₂locus was observed; two alleles, Ch ₂ ^s and Ch ₂ ^m, are suggested.     

Cytogenetical studies on African rice,Oryza glaberrima Steud. 3. Primary trisomics produced by pollinating autotriploid with diploid

Summary In order to promote cytogenetical studies on Oryza glaberrima (2n=2x=24), I produced primary trisomics in the progeny of the autotriploid. When the autotriploid was pollinated with the diploid, 136F1 seeds (5.8% of the number of spikelets pollinated) were obtained. The numbers of chromosomes of 31 surviving progeny varied from 24 to 28, with plants having 2n=25 occurring at the highest frequency (34.4%). The primary trisomics differed from one another as well as from the normal disomics in many aspects. The differences were attributed to a single extra chromosome in each trisomic type. Nine primary trisomics were classified into 8 types on the basis of morphological and reproductive features. Seeds were obtained from all primary trisomics except for Type D by self pollination, open pollination or pollination with the disomics. I was able to maintain 7 types of primary trisomics by seed propagation. The primary trisomics which are capable of expressing subtle genetic dissimilarities should be useful for studying the relationship between the two cultivated species of rice at the level of individual chromosomes.     

Trisomic genetic analysis of aroma in three Japanese native rice varieties (Oryza sativa L.)

Information on the genetics of aroma in rice facilitates breeding and selection of new aromatic varieties with high yield and good quality. Objective of the present study was to make clear the number of genes controlling aroma, and the allelism of aroma genes and the location of aroma gene(s) on the chromosome in three Japanese native aromatic rice varieties (Kabashiko, Shiroikichi and Henroyori). Lack of leaf aroma in all F₁ plants of non-aromatic/aromatic crosses indicated the recessive nature of aroma, and the segregation ratios (3:1) of non-aromatic to aromatic plants in its F₂ populations from Nipponbare/aromatic varieties crosses revealed that each of the three aromatic varieties contains a single recessive gene for aroma. Through trisomic analysis, the segregation of non-aromatic and aromatic plants in all F₂ populations from the crosses between trisomics lines NT8, with an extra chromosome 8, and aromatic varieties deviated significantly from disomic segregation of 3:1 ratios, and fitted to trisomic segregation, however, in other F₂ populations derived from other 7 types of trisomic F₁ plants, the segregation ratios of non-aromatic to aromatic were 3:1, indicating that the single recessive aroma gene was located on chromosome 8 in three aromatic varieties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic Analysis of Resistance to Green Leafhopper in Rice

The inheritance of resistance to green leafhopper, Nephotettix impicticeps Ichi, was studied in 11 cultivars of rice, Oryza saliva L. These resistant cultivars were crossed with the susceptible cultivar ‘TN1’. The materials consisted of F₁, F₂ and F₃ populations including parents which were assessed by the bulk screening test. It was found that resistance in the cultivars TR36′, UPR254-35-3′-2′, ‘Jhingasail’, ‘Govind’, ‘RP825-45-1-3’, ‘MRC603-303’, ‘RD4’, and ‘Irat104 ’ was conditioned by a single dominant gene, whereas resistance in ‘Ptb8’ IR9805-97-1′, and ‘BG367-7’ was controlled by one recessive gene. The test on the allelic relationships of the resistance genes in the test cultivars with the known genes Glb1 and Glb2 revealed that the single dominant gene that conveyed the resistance in ‘UPR254-35-3-2’ and ‘Jhingasail’ was allelic to Glh1 and segregated independently of Glh2. The resistance in ‘Govind’ and ‘RP82S-45-1-3’ was governed by the Glh2 gene which was independent of Glh1. The test cultivars ‘IR36’;. ‘MRC603-303’, ‘RD4’. and Irat104 ’ had a dominant gene for resistance which was nonallelic to Glb1 and Glb2. The recessive gene which conditioned the resistance in ‘Ptb8’, ‘IR9805-97-1’, and ‘BG367-1’ segregated independently of Glh1 and Glh2. Eleven trisomics in an ‘TR36’ background were crossed with ‘Java’, a cultivar susceptible to green leafhopper. The segregation pattern of the F₂ and backcross generations revealed that the Glb6 gene was located on chromosome 5.     

Inheritance of internal pigmentation in green cabbage (Brassica oleracea var. Capitata L.)

Summary Internal anthocyanin pigmentation (IP) in otherwise normally green cabbage occurs in a number of Oregon State University breeding lines. Extracted pigment, tested for spectral absorption and for color reactions with lead acetate and aluminium chloride, was similar but not necessarily identical to pigment extracted from red cabbage cultivar Redman. When IP line R52 was crossed with normal green line C70, the F₁, F₂ and backcross progenies indicated that IP at the intensity found in R52 was determined by a single factor in homozygous condition, with intermediate levels of IP expressed by the heterozygous genotypes. Modifying factors also appear to influence the level of IP. In the cross R52 (IP)×R51 (normal green), expression of IP in the F₁ was much reduced. The F₂ failed to fit the expected 3 IP: 1 green ratio due to an excess of green plants, but instead, closely fit a 9:7 ratio. This may have resulted from incomplete expression of IP because of modifiers, rather than from the effects of a second major gene. An allele at the A (anthocyanin) locus of B. oleracea is tentatively proposed and designated A ^IP or a ^IP pending further identification.Oregon Agricultural Experiment Station Technical Paper No. 4690.     

Identification of SSR markers linked to the Phytophthora resistance gene Rps1-d in soybean

To identify markers for the Phytophthora resistance gene, Rps1‐d, 123 F_{2 : 3} families were produced from a cross between Glycine max (L.) Merr. ‘Tanbakuro’ (a Japanese traditional black soybean) and PI103091 (Rps1‐d) as an experimental population. The results of virulence tests produced 33 homozygous resistant, 61 segregating and 29 homozygous susceptible F_{2 : 3} families. The chi‐squared test gave a goodness‐of‐fit for the expected ratio of 1 : 2 : 1 for resistant, segregating and susceptible traits, suggesting that the inheritance of Rps1‐d is controlled by a monogenic dominant gene. Simple sequence repeat (SSR) analyses of this trait were carried out using the cultivars ‘Tanbakuro’ and PI103091. Sixteen SSR primers, which produced 19 polymorphic fragments between the two parents, were identified from 41 SSR primers in MLG N. Eight SSR markers were related to Rps1‐d, based on 32 of the 123 F_{2 : 3} families, consisting of 16 homozygous resistant and 16 homozygous susceptible lines. The remaining 91 families were analysed for these eight markers, and a linkage map was constructed using all 123 F_{2 : 3} families. The length of this linkage group is 44.0 cM. The closest markers, Sat_186 and Satt152, are mapped at 5.7 cM and 11.5 cM, respectively, on either side of the Rps1‐d gene. Three‐way contingency table analysis indicates that dual‐marker‐assisted selection using these two flanking markers would be efficient.