Inheritance and potentials of a mutated dwarfing gene ndf1 in Brassica napus

A dwarf mutant ‘NDF‐1′, approximately 70 cm high, was derived from a 200‐cm high doubled haploid (DH) line ‘3529’ (Brassica napus), seeds of which were jointly treated with chemical inducers and bombardment of fast neutron. The leaves of the ‘NDF‐1’ mutant were wrinkled and thicker compared with the wild‐type control. The mutant had much lower values than its original parents for all agronomic traits, except for its seed weight. A genetic analysis revealed that dwarfism is under the control of a major gene (designated as ndf1) with a mainly additive effect and non‐significant dominance effect. Because of the high level of resistance to lodging, breeding programmes for double low dwarf oilseed rape and heterosis utilization were initiated. Some new dwarf strains with improved agronomic performance were developed. The hybrid of the cross between the tall parent and the dwarf line showed increased harvest index and significantly higher seed yield than the tall parent or the control variety ‘Zhongyou 821’ and presented an estimated heterosis vigour rate as high as 12.5–25.8%. The dwarf trait will be a promising marker for a simple, economic and efficient way to control the purity of F₁ hybrid varieties in hybrid production of B. napus.     

Indica-Japonica differentiation of paddy rice and its relationship with heterosis

The Indica‐Japonica differentiation of three photoperiod‐sensitive and/or thermosensitive genetic male‐sterile rice (PGMS or TGMS, respectively) lines and 47 male parental lines from seven ecotypes were studied for their restriction fragment length polymorphism marker data to determine which ecotype crosses with the three PGMS and/or TGMS lines could lead to higher yield potential, and to estimate the relationship between the Indica‐Japonica differentiation of parents and heterosis in grain yield and its components. The results indicated that hybrids derived from ‘N422s’ and the early‐middle ripening Indica varieties from southern China, and hybrids between ‘Pei'ai64s’ and three Japonica ecotypes, including North‐eastern Japonica varieties, restoring lines of Japonica hybrid rice and north China Japonica varieties, showed the highest grain yields. There was less variation of yield among the F1s between ‘108s’ and the seven ecotypes than among the other F₁s. Highly significant positive correlations between heterosis of the F₁ yield and genetic distance of the parents were detected, although the correlation between F₁ yield performance and genetic distance did not reach a significant level. Considerable variation of correlation between heterosis and genetic distance was also detected in the Indica × Indica crosses and Indica × Japonica crosses. There was much higher correlation (r = 0.63) between the F₁ yield performance and the genetic distance of parents in the Indica × Indica crosses than in the others. It is proposed that a genetic distance of 0.4‐0.8 between the two parents of hybrid rice might be appropriate not only for F₁ performance, but also for heterosis.     

Inheritance of Striga hermonthica adaptive traits in an early‐maturing white maize inbred line containing resistance genes from Zea diploperennis

Striga hermonthica can cause as high as 100% yield loss in maize depending on soil fertility level, type of genotype, severity of infestation and climatic conditions. Understanding the mode of inheritance of Striga resistance in maize is crucial for introgression of resistance genes into tropical germplasm and deployment of resistant varieties. This study examined the mode of inheritance of resistance to Striga in early‐maturing inbred line, TZdEI 352 containing resistance genes from Zea diploperennis. Six generations, P₁, P₂, F₁, F₂, BC₁P₁ and BC₁P₂ derived from a cross between resistant line, TZdEI 352 and susceptible line, TZdEI 425 were screened under artificial Striga infestation at Mokwa and Abuja, Nigeria, 2015. Additive‐dominance model was adequate in describing observed variations in the number of emerged Striga plants among the population; hence, digenic epistatic model was adopted for Striga damage. Dominance effects were higher than the additive effects for the number of emerged Striga plants at both locations signifying that non‐additive gene action conditioned inheritance of Striga resistance. Inbred TZdEI 352 could serve as invaluable parent for hybrid development in Striga endemic agro‐ecologies of sub‐Saharan Africa.     

Comparison of two fertility restoration systems against photoperiod-sensitive cytoplasmic male sterility in wheat

A ‘two‐line system’ using photoperiod‐sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm under a long‐day photoperiod ( 15 h) has been proposed as a new means of producing hybrid varieties in common wheat. The PCMS line is maintained by self‐pollination under short‐day conditions, and hybrid seeds can be produced through outcrossing of the PCMS line with a pollinator under long‐day conditions. Two kinds of fertility restoration systems against the PCMS are known. One is involved with a set of multiple fertility‐restoring (Rf) genes in the wheat cultivar ‘Norin 61’ located on (at least) chromosomes 4A, 1D, 3D and 5D. The other is controlled by a single dominant major Rf gene, Rfd1, located on the long arm of chromosome 7B in the wheat cultivar ‘Chinese Spring’. To examine the degree of fertility restoration by these two systems, nine PCMS lines were crossed with ‘Norin 61’ and ‘Chinese Spring’ as the restorer lines, and the F₁ hybrids were investigated. The degree of fertility restoration was estimated by comparing the seed set rates in the F₁ hybrids having the Ae. crassa cytoplasm and those with normal cytoplasm. The results revealed that the fertility restoration ability of a set of multiple Rf genes in ‘Norin 61’ was higher than that of the Rfd1 gene in ‘Chinese Spring’.     

A new male sterile mutant LZ in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Genetic male sterility (GMS) genes in wheat (Triticum aestivum L.) can be used for commercial hybrid seed production. A new wheat GMS mutant, LZ, was successfully used in the 4E-ms system for producing hybrid wheat, a new approach of producing hybrid seed based on GMS. Our objective was to analyse the genetic mechanism of male sterility and locate the GMS gene in mutant LZ to a chromosome. We firstly crossed male sterile line 257A (2n = 42) derived from mutant LZ to Chinese Spring and several other cultivars for determining the self-fertility of the F₁ hybrids and the segregation ratios of male-sterile and fertile plants in the F₂ and BC₁ generations. Secondly, we conducted nullisomic analysis by crossing male sterile plants of line 257A to 21 self-fertile nullisomic lines as male to test the F₁ fertilities and to locate the GMS gene in mutant LZ to a chromosome. Thirdly, we conducted an allelism test with Cornerstone, which has ms1c located on chromosome 4BS. All F₁s were male fertile and the segregation ratio of male-sterile: fertile plants in all BC₁ and F₂ populations fitted 1:1 and 1:3 ratios, respectively. The male sterility was stably inherited, and was not affected by environmental factors in two different locations or by the cytoplasm of wheat cultivars in four reciprocal cross combinations. The results of nullisomic analysis indicated the gene was on chromosome 4B. The allelism test showed that the mutant LZ was allelic to ms1c. We concluded that the mutant LZ has common wheat cytoplasm and carries a stably inherited monogenic recessive gene named ms1g.     

Chasmogamous mutant,a novel character enabling commercial hybrid seed production in mungbean

Mungbean (Vigna radiata (L.) Wilczek) is a self-pollinating crop that displays significant hybrid vigor in seed yield of F₁ hybrids. Thus there is the possibility to use hybrid varieties as a breakthrough to raise the yield plateau of mungbean. However, hybrid mungbean seeds can only be accomplished by hand-pollination and thus commercial production is not possible. To encourage hybrid seed set, the plant breeder needs to develop characters that promote higher outcrossing rate such as open flower (chasmogamy). In this experiment, new chasmogamous mutants were induced by gamma irradiation at the rate of 100 and 200 Gy. The mutants were identified at a low rate of 0.4–0.7% in the M₂ generation of accession V1197, and observed for their purity by growing in plant-to-row in the M₃ and M₄ generations. A uniform chasmogamous line was hybridized to normal flower lines to study the inheritance of this character. All F₁ plants had normal flowers, while the F₂ plants segregated well with 3 normal : 1 chasmogamous ratio. When the F₁ was backcrossed to the chasmogamous parent, the progeny gave a ratio of 1 normal to 1 chasmogamous. Thus, chasmogamy was controlled by a single recessive gene, cha.     

Inheritance and allelic relationships of fertility restoration genes for seven new sources of male-sterile cytoplasm in sunflower

The inheritance of fertility restoration of six mitomycin C and streptomycin‐induced cytoplasmic male‐sterile (cms) mutants and one cms line derived from Native American cultivar PI 432513 in sunflower was evaluated. These seven new cms sources were also compared with the commercially used cms PET1 (Helianthus petiolaris Nutt.) cytoplasm, using USDA inbred lines with restoration genes (Rf₁) specific for cms PET1 and new restoration lines identified for cms PI 432513. Restoration genes for cms PI 432513 were found in ‘Armavir’, VNIIMK, P21 and male‐fertile (MF) plants of PI 432513. F₂ and F₃ segregation ratios of crosses between cms PI 432513 and these restoration sources indicated a single dominant gene controlled fertility restoration. Progenies of cms PI 432513 testcrossed with F₁’s of half‐diallel crosses among the respective four homozygous restoration lines and RHA 274 suggested that the restoration genes of RHA 274, VNIIMK, P21 and PI 432513 were at the same locus. Restoration genes from VNIIMK, P21 and PI 432513 satisfactorily restored pollen stainability in the heterozygous condition. A very weak expression of the Rf gene in ‘Armavir’ was observed in the heterozygous condition. Fertility restoration capability of these genes for the six mutant cms HA 89 and cms HA 89 (in PET1 cytoplasm) was observed. The mutant cms HA 89 lines were also restored completely by RHA 266, RHA 274, RHA 280 and RHA 296, and F₂’s segregation ratios indicated single dominant gene control, implying a common cytoplasmic male sterility in all lines. F₁’s of half‐diallel crosses among RHA 266, RHA 273, RHA 274, RHA 280 and RHA 296 were testcrossed onto the cms lines, and their all MF progenies among lines, except RHA 280, confirmed that fertility restoration was controlled by a single Rf₁ gene locus. The restoration gene in confection line RHA 280, namely Rf₃, was at a different locus than Rf₁ and was equally capable of restoring all the cms lines. Cms HA 89 mutants and cms PI 432513 are in H. annuus cytoplasm, and are agronomically equal in hybrid performance to the cms PET1 used in commercial sunflower hybrids. These new cms lines will provide immediate alternative cms sources for reducing the genetic vulnerability resulting from the exclusive use of the single cms source PET1 in sunflower hybrid production.     

Transgene introgression from Brassica napus to different varieties of Brassica juncea

Transgene introgression from transgenic rapeseed (Brassica napus) to different varieties of B. juncea was assessed in this study. Crossability between a transgenic rapeseed line Z7B10 (pollen donor) and 80 cultivars of 16 B. juncea varieties (including two wild accessions) was estimated by artificial pollination in a greenhouse. As a result, interspecific crossability between the transgenic Z7B10 line and the 80 B. juncea cultivars varied considerably, with seeds per flower from 0.00–10.67. Seed germination rates of the interspecific F₁ hybrids ranged from 49.0%–89.3%. The estimated frequencies of natural gene flow from the transgenic Z7B10 line to 10 B. juncea cultivars with different uses in the experiment field varied from 0.08% to 0.93%. The natural F₁ hybrids were highly sterile, with seeds per silique ranging from 0.27 to 1.03. In addition, seeds per flower of hybrid descendants varied from 0.02 to 0.22 when F₁ hybrids were self‐pollinated, and those ranged from 0.03 to 0.30 when F₁ hybrids were backcrossed with their corresponding B. juncea parents. Results of this study suggest a low level of transgene introgression from transgenic rapeseed to different B. juncea varieties, which provides a sound scientific basis for the safety management of coexisting transgenic B. napus and B. juncea varieties in China.     

Pyramiding of genes conferring resistance to Tomato yellow leaf curl virus from different wild tomato species

Tomato (Solanum lycopersicum) production in tropical and subtropical regions of the world is limited by the endemic presence of Tomato yellow leaf curl virus (TYLCV). Breeding programmes aimed at producing TYLCV‐resistant tomato cultivars have utilized resistance sources derived from wild tomato species. So far, all reported breeding programmes have introgressed TYLCV resistance from a single wild tomato source. Here, we tested the hypothesis that pyramiding resistances from different wild tomato species might improve the degree of resistance of the domesticated tomato to TYLCV. We have crossed TYLCV‐resistant lines that originated from different wild tomato progenitors, Solanum chilense, Solanum peruvianum, Solanum pimpinellifolium, and Solanum habrochaites. The various parental resistant lines and the F₁ hybrids were inoculated in the greenhouse using viruliferous whiteflies. Control, non‐inoculated plants of the same lines and hybrids were exposed to non‐viruliferous whiteflies. Following inoculation, the plants were scored for disease symptom severity, and transplanted to the field. Resistance was assayed by comparing yield of inoculated plants to those of the control non‐inoculated plants of the same variety. Results showed that the F₁ hybrids between the resistant lines and the susceptible line suffered major yield reduction because of infection, but all hybrids were more resistant than the susceptible parent. All F₁ hybrids resulting from a cross between two resistant parents, showed a relatively high level of resistance, which in most cases was similar to that displayed by the more resistant parent. In some cases, the hybrids displayed better levels of resistance than both parents, but the differences were not statistically significant. The F₁ hybrid between a line with resistance from S. habrochaites and a line with resistance from S. peruvianum (HAB and 72‐PER), exhibited the lowest yield loss and the mildest level of symptoms. Although the resistance level of this F₁ hybrid was not statistically different from the level of resistance displayed by the 72‐PER parent itself, it was statistically better than the level of resistance displayed by the F₁ hybrids between 72‐PER and any other resistant or susceptible line.     

Identification of salt tolerance‐improving quantitative trait loci alleles from a salt‐susceptible rice breeding line by introgression breeding

To improve salt tolerance of two elite rice varieties, Ce258 and Zhongguangxiang1 (ZGX1), two sets of introgression lines (ILs) each comprising 200 BC₁F₁₀ lines derived from a common donor, IR75862, and two recipient parents, Ce258 and ZGX1, were used for mapping of QTLs for four salt tolerance‐related traits at the seedling stage. Although the three parents were susceptible to salt, the two IL populations showed transgressive segregations for salt tolerance with 12 and 8 salt tolerance ILs in the Ce258‐ILs and ZGX1‐ILs. Eighteen main‐effect QTLs were identified for the four traits in the two IL populations, and the IR75862 alleles at most loci showed increased and decreased salt tolerance in the ZGX1 and Ce258 backgrounds, suggesting overwhelming genetic background effects on QTL detection for salt tolerance. The qDSS11 simultaneously detected in the two backgrounds was validated in a F₂ population derived from a salt tolerance line and ZGX1. Our results indicated that salt tolerance‐enhancing allele could be identified in the elite susceptible breeding lines and that introgression of the favourable alleles could facilitate the development of superior lines with greater salt tolerance levels.     

Development of photoperiod-sensitive cytoplasmic male sterile (PCMS) wheat lines showing high male sterility under long-day conditions and high seed fertility under short-day conditions

A “two-line system” using photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm under long-day photoperiods (≧15 h) has been proposed as a means of producing hybrid varieties in common wheat (Triticum aestivum). The PCMS line is maintained by self-pollination under short-day conditions, and hybrid seeds can be produced through outcrossing of the PCMS line with a pollinator line under long-day conditions. Our previous studies revealed that PCMS lines showing complete male sterility under long-day conditions are necessary for practical hybrid wheat breeding, especially to obtain high hybrid purity in F₁ seeds. Furthermore, practical PCMS lines should have high seed fertility under short-day conditions, which is associated with female fertility. Wheat cv. Norin 26 with Ae. crassa cytoplasm exhibits high seed fertility under short-day conditions, and cv. Fujimikomugi with Ae. crassa cytoplasm shows high male sterility under long-day conditions. Here we developed practical PCMS lines derived from the F₁ generation of Norin 26 and Fujimikomugi (with Ae. crassa cytoplasm) that were then backcrossed to elite wheat lines.     

Development of a kompetitive allele‐specific PCR marker for selection of the mutated Wx‐D1d allele in wheat breeding

Waxy (Wx) protein is a key enzyme for synthesis of amylose in endosperm. Amylose content in wheat grain influences the quality of end‐use products. Seven alleles have been described at the Wx‐D1 locus, but only two of them (Wx‐D1b, Wx‐D1e) were genotyped with codominant markers. The waxy wheat line K107Wx1 developed by treating ‘Kanto 107’ seeds with ethyl methanesulphonate carries the Wx‐D1d allele. However, no molecular basis supports this nomenclature. In the present study, DNA sequence analysis confirmed that a single nucleotide polymorphism in the sixth exon of Wx‐D1 changed tryptophan at position 301 into a termination codon. Based on this sequence variation, a PCR‐based KASP marker was developed to detect this point mutation using 68 BC₈F₁ plants and 297 BC₈F₂ lines derived from the cross ‘Ningmai 14’*9/K107Wx1. Combined with codominant markers for the Wx‐A1 and Wx‐B1 alleles, waxy and non‐waxy near‐isogenic lines were distinguished. The KASP marker was efficient in identifying the mutant allele and can be used to transfer waxiness to elite lines.     

Genetic and agronomic analyses of red rice-Clearfield hybrids and their progeny produced from natural and controlled crosses

Clearfield rice technology is a popular method for controlling noxious red rice weeds (Oryza sativa L.) in commercial rice fields in the southern U.S. Previous research has detected red rice-Clearfield variety F₁ hybrids at low rates in Louisiana and Arkansas. The first research objective was to determine genetic control of imazethapyr resistance in F₁ hybrids and F₂ populations derived from natural and controlled hybridizations of red rice and Clearfield rice. The second objective was to characterize and compare agronomic performance of the hybrids and their progeny with Clearfield varieties. Genetic analysis showed that imazethapyr resistance was dominant in all tested F₁ hybrids with single and two-gene inheritance observed across composite F₂ populations. F₁ hybrids exhibited high levels of variation for plant height, heading date, and seven reproductive traits. Heterosis was observed in the hybrids versus Clearfield varieties for plant height, heading date, seed-bearing tillers, panicle length, and spikelets/panicle. While seed production of the F₁ hybrids was generally inferior to that of the commercial varieties, one red rice/CL121 hybrid produced greater seeds/panicle than the CL121 commercial parent. Extensive variation was observed for all measured traits in the F₂ populations derived from either natural or controlled crosses. Results from this study indicate that red rice/Clearfield F₁ hybrids normally exhibit low reproductive seed capacity, but a small proportion of the subsequent F₂ progeny can produce high fecundity levels. Effective stewardship practices are therefore warranted to reduce the occurrence of such hybrids and their offspring to ensure continued success of the Clearfield technology. Approved for publication by the Director of the Louisiana Agricultural Experiment Station as manu number 2008-306-1392.     

Effect of parental genotypes and colchicine treatment on the androgenic response of wheat F1 hybrids

The effect of the parental genotypes and colchicine treatment on the androgenic response of wheat (Triticum aestivum L.) F1 hybrids was studied. For this, anthers from three F1 hybrids and their parents were cultured on W14 initiation medium and W14 supplemented with 0.03% colchicine. The number of responding anthers, microspore‐derived structures/100 anthers, green plants/embryos cultured, green plants/100 anthers and albino plants/100 anthers were recorded. It was observed that embryo formation and plant regeneration ability were genetically controlled and genotype dependent. In both treatments the variety Kavkaz had a significantly higher percentage of responding anthers, microspore‐derived structures and green plants/100 anthers than the other genotypes. On the other hand, the variety Myconos also demonstrated high microspore‐derived structure production and green plant regeneration when treated with colchicine. The good response observed in these two varieties indicates the importance of colchicine treatment only for certain genotypes. Green plant production capacity of the hybrids was intermediate to that of the parental varieties. As one parent with a high or even an intermediate response to anther culture could lead to the production of sufficient (for breeding purposes) green plants from the F₁ hybrids, it was concluded that screening the inbred lines for the response to anther culture with and without colchicine treatment could contribute to utilization of breeding material with a low response to anther culture via the proper hybrid combinations.     

Genetic diagnosis of Rehmannia species micropropagated by tip tissue culture and an F1 hybrid by RAPD analysis

Shoot formation was induced from the tip tissue of Rehmannia glutinosa f. hueichingensis on hormone-free Murashige-Skoog medium within 4 weeks of culture. Shoots were propagated on Murashige-Skoog medium supplemented with l.0mg/l benzy0ladenine for 4 weeks. Propagated shoots rooted on the hormone-free Murashige-Skoog medium during 4 weeks of culture. Total DNA was extracted from the leaves of a F₁ hybrid and its parents. R. glulinosa f. huekliingensis and R. glutinosa var, purpurea. Analysis of random-amplified polymorphic DNA (RAPD) using 10 arbitrary oligonucleotide 10-mers. showed the genetic homogeneity ofthe above three species. The F₁ hybrid was genetically intermediate between both parental plants, compared with the genetic distance between the F₁ hybrid and individual parents. Furthermore, the comparison of the band patterns between the F₁ hybrid, obtained from the crossing clearly showed that parts of the bands of both parents. R. glutinosa f. hueichingensis and R. glutinosa var. purpurea, were introduced into the F₁ hybrid.     

Genetics of a high-selfing trait in pigeonpea

Summary A true-breeding line characterized by free filaments of anthers and modified keel petal was derived from F₂ population of an intergeneric cross between Cajanus cajan (L.) Millsp. and Atylosia lineata W. & A. This variant, designated as partial cleistogamy, favours a high level of self-fertilization. The inheritance of this trait was studied in the F₁, F₂, F₃, and BC₁F₁ generations of three crosses. The results suggest that the partial cleistogamy trait is governed by a single recessive gene, designated as pct.     

Barley mutant heterosis and fixation of'F1-performance'in doubled haploid lines

The phenomenon of mutant heterosis was studied in barley using F₁ hybrids developed from crosses involving two mutants derived from the same parent variety (067AR× 032AR), or from crosses of mutants with their parent varieties (Diva × 228DV; 437MG × Mg 4170). The agronomic performance (plant height, tillers per plant, kernel number and weight per plant) of F₁ hybrids was evaluated in relation to the corresponding parent variety used for mutant development. Wide-space sowing (0.O6 m²/plant) was applied to allow the full expression of hybrid vigour. The hybrids significantly exceeded their parent varieties in various yield parameters in each year of the experiment, Depending on the cross, the level of heterosis ranged from 39.45% to 82.1% for kernel number and from 44.45% to 91.2% for kernel weight, as an average of observations over three years. The increased yield of hybrids was accompanied by an increase in spikes/plant, without significant changes, in most cases, in yield components such as kernels/spike and 1000 kernel weight. The height of F₁ plants remained similar to the corresponding parent variety. Doubled haploicls (DH) were developed through anther culture from three F₁ hybrids to determine whether the heterotic effect could be fixed, even partly, in homozygous lines. Twenty-eight, 42 and 68 DH lines per cross were produced, and evaluated in the field, space-planted at 0.06 m²/plant, together with hybrids and parent varieties. The best-performing DH lines were evaluated again the following season in a conventional field trial. We were able to select 1.5 -14.3% of‘F₁,-performing’DH lines per hetorotic cross combination, which, in two years of studies, reached the yield of heterotic hybrids and significantly out-yielded the parent variety in plot. The yield potential of DH lines was better expressed under a wide sowing density, but even under normal growing conditions, the yield of the best selected DH lines surpassed their corresponding parent varieties by 17.77ndash;30.1%.     

新质源CMS-FA杂交稻系统的亲本资源筛选

用新质源雄性不育系金农1A(CMS-FA)作母本, 分别与来自10个国家和国内13个省份的220个水稻品种组配成杂交种, 考察F₁代的花粉染色率、套袋结实率和自然结实率。在F₁代中, 当这3项育性指标均≤10%时, 显示父本品种具有雄性不育保持能力, 因而将其划分为保持系资源; 当3项育性指标均≥80%时, 显示父本品种具有雄性不育恢复能力, 将其划分为恢复系资源; 此外的其他父本品种, 即3项育性指标中任何一项指标>10%或<80%, 既不能作为保持系, 也不能作为恢复系, 被划分为非杂交稻亲本资源。在220个水稻品种中, 可作为金农1A保持系的有122个, 占55.5%; 未发现恢复系亲本; 非杂交稻亲本品种有98个, 占44.5%。CMS-FA型的杂交稻亲本资源利用率为55.5%。对照野败型不育系珍汕97A(CMS-WA)的保持系亲本品种有44个, 占20.0%; 恢复系亲本品种42个, 占19.1%; 非杂交稻亲本品种134个, 占60.9%。CMS-WA型的杂交稻亲本资源利用率为39.1%。CMS-FA系统比CMS-WA系统的亲本稻种资源利用率高16.4个百分点, 尤其是保持系资源利用率高35.5个百分点(近1.8倍)。国外品种的育性普遍低于国内品种。     

Interspecific amphiploid‐derived alloplasmic male sterility with defective anthers,narrow disc florets and small ray flowers in sunflower

The cytoplasmic male‐sterility (CMS)/fertility‐restoration system is important for hybrid sunflower (Helianthus annuus L.) seed production. The objective of this study was to characterize two novel alloplasmic CMSs, designated CMS GRO1 and CMS MAX3, with defective anthers, narrow disc florets with no swollen corolla, and short, narrow ray flowers derived from two tetraploid amphiploids (AMPs). Among 26 tested lines, only AMP Helianthus cusickii/P 21 and HA 410 failed to restore male‐fertility. Segregation of CMS, male‐fertile plants and plants with reduced male‐fertility was observed both in the testcross progeny of a six line half‐diallel cross of F₁s with CMS MAX3 and in an F₂ population of CMS GRO1 × RHA 274. Male‐fertility restoration was controlled by at least two dominant genes. Detailed analysis of the mitochondrial genes may provide insight into the differences between these CMSs and other CMS lines. The new CMSs will facilitate the studies of the incompatibility between cytoplasmic and nuclear genes, especially for the alloplasmic CMS involving perennial species, and also provide unique ornamental flower types and CMS sources for hybrid sunflower breeding.     

Novel Wx alleles induced by chemical mutagens in rice,Oryza sativa L.

From mutant pools of two Taiwanese elite japonica cultivars, Tainung 67 and Taikeng 8, we identified 13 mutant lines possessing opaque endosperm with relatively low amylose contents (AC) ranging from 1.5% to 7.1%. Because of different AC, paste viscosities of these 13 mutant lines differed, as revealed by palatability and physicochemical properties. The mutated gene conferring opaque endosperm was isolated from the F₂ population of one mutant line, WY1× indica cv. ‘Taichung Sen 17’, by positional cloning, revealing a G3018→A3018 substitution at exon 9 of Waxy leading to a non‐synonymous mutation from alanine to valine. Two additional alleles were identified from the other 12 mutant lines, for which single‐nucleotide substitutions G2708 → A2708 and G3029 → A3029 occurred in exons 8 and 9, leading to non‐synonymous mutations from arginine to histidine and glutamic acid to lysine, respectively. The three novel wx alleles had different effects on grain quality, specifically on eating and cooking quality, and could be applied in rice breeding programmes to develop new low AC varieties by marker‐assisted selection.