Inheritance of resistance to race F of broomrape in sunflower lines of different origins

A new race F of broomrape overcomes all known resistance genes in cultivated sunflower, but recently, sources of resistance against race F have been developed. The objective of the present research was to study the inheritance of resistance to race F in crosses between 12 resistant sunflower breeding lines, derived from three different sources of resistance, and the susceptible male‐sterile line P‐21. Parental lines and F₁, F₂, F₃ and BC₁ generations were evaluated for broomrape resistance. Segregations in the F₂ and BC₁ to resistant parent approached resistant to susceptible ratios of 1: 15 and 1: 3, respectively, in most of the crosses, suggesting a double dominant epistasis. However, segregations of 3: 13 and 1: 1 for F₂ and BC₁, respectively, indicating a dominant‐recessive epistasis, were also found. The F₃ data confirmed these results. Owing to the recessive nature of this resistance, it must be incorporated into both parental lines for developing resistant hybrid cultivars.     

Reproductive behaviour and broomrape resistance in interspecific hybrids of sunflower

Interspecific hybrids and backcross generations between the wild perennial species Helianthus resinosus, Helianthus paucifiorus, Helianthus laevigatus, Helianthus nuttallii ssp. nuttallii T. & G. and Helianthus giganteus, resistant to broomrape (Orobanche cernua) and susceptible inbred lines were obtained to study crossability to cultivated sunflower and the transmission and expression of resistance to this parasitic weed. Conventional crosses with all the species tested were successful except for the crosses with diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F₁ hybrids with hexaploid species and lowest for those with the diploid H. giganteus. We evaluated F₁, BC₁F₁, some BC₂F₁ plants and the wild and cultivated parents. The wild species and interspecific hybrids were resistant to broomrape infection except for H. nuttallii, which showed segregation, indicating that the resistance is dominant. The crossability and resistance of F₁, and back-cross generations of species with different ploidy levels indicate that the transfer of broomrape resistance to cultivated sunflower is feasible.     

Identification of PCR markers linked to different Or genes in sunflower

Broomrape is a parasitic plant that significantly decreases yield of sunflower. Breeding for resistance has proved to be the most efficient method for suppressing broomrape infestation in the field; however, new races of parasite constantly emerge, and new resistance genes need to be discovered and introduced into cultivated sunflower lines. The aim of this work was to test SSR markers from linkage group 3 (LG3) to investigate whether they could be used for identification of a particular Or gene. Twenty sunflower inbred lines were used, and polymorphism between the lines with various resistance genes and genetic background was investigated. The used markers revealed DNA polymorphism between the investigated lines. Strong association of markers from LG3 with Or₆, as well as Or₄ and Or₂ genes, was found. Identified markers could be used for introduction of these resistance genes into commercial sunflower lines and for establishment and identification of differential lines.     

Inheritance of resistance to two races of sunflower downy mildew (Plasmopara halstedii) in two Helianthus annuus L. lines

Sunflower downy mildew caused by Plasmopara halstedii is an important disease of sunflower capable of causing losses of more than 80% of production. Races 100, 300, 310, 330, 710, 703, 730 and770 of the fungus have been identified in Spain. Race 703, of high virulence, has been identified frequently in the northeast, while race 310 seems to occur over the south, the main sunflower growing region of the country. Oil sunflower lines RHA-274 and DM4 were studied for their resistance to races 310(RHA-274 and DM4) and 703 (DM4). In each cross, only one plant of the resistant parent was crossed to the inbred susceptible line HA-89 (or cmsHA-89).Plants from F₂ and backcross(BC₁F₁ to susceptible parent)generations were evaluated for fungal sporulation on true leaves and/or cotyledons. The resistant-to-susceptible ratios obtained in the F₂ and BC₁F₁ progenies from the crosses cmsHA-89 × RHA-274 and HA-89 × DM4suggested that one major gene in each line is responsible for resistance to race 703.The segregations of the progenies of the cross HA-89 × DM4 inoculated with race 703also fitted the ratios 1:1 and 3:1 (for BC₁F₁ and F₂, respectively)corresponding to control of resistance by a single dominant gene. In RHA-274, the gene for resistance to race 310 was designated Pl ₉, whereas Pl _v is tentatively proposed to designate the gene in DM4 responsible for resistance to races310 and 703. This revised version was published online in August 2006 with corrections to the Cover Date.     

Inheritance of reduced plant height in the sunflower line Dw 89

The objective of the present research was to study the inheritance of reduced plant height in the sunflower line Dw 89. Plants of the cytoplasmic male sterile version of this line, cmsDw 89 (mean plant height of 47.4 cm) were crossed with plants of the restorer line RHA 271 (mean of 120.9 cm). F₁ plants averaged 120.4 cm, which indicated dominance of standard over reduced plant height. F₂ plants followed a segregation pattern of 1 : 15 (reduced : normal height), suggesting that reduced plant height in Dw 89 is controlled by alleles at two loci, designated Dw1 and Dw2. Class assignment in the F₂ was confirmed through the evaluation of the F₃ generation. Backcrosses to Dw 89 segregated with 1 : 3 (reduced : normal height) ratios, which confirmed the digenic inheritance of the trait. The evaluation of plant height distributions in F₃ families suggested possible genetic interaction between the Dw1 and Dw2 loci.     

Genetic analysis of gene‐specific resistance to mungbean yellow mosaic virus in mungbean (Vigna radiata)

Six intervarietal crosses involving two resistant and three susceptible genotypes of mungbean were attempted with the objectives to determine the mode of inheritance of gene‐specific Mungbean Yellow Mosaic Virus (MYMV) resistance. An infector row technique along with artificial inoculation was used for evaluating parents, F₁, F₂ and F₃ plants for MYMV resistance. Disease scoring for MYMV indicated that F₁s were highly susceptible as were the susceptible parents while resistant parent exhibited resistant reaction. The F₂ progeny segregated in the ratio of 9 S:3 MS:3 MR:1 R suggesting that the resistance was governed by digenic recessive genes (r_m1 and r_m2). When one gene (r_m1) was present in the homozygous recessive condition in different plants, it conferred moderately susceptible (MS) reaction, whereas when other gene (r_m2) was in homozygous condition, moderately resistant (MR) reaction was obvious. When both genes (r_m1 and r_m2) were present together in the homozygous recessive condition, resistant reaction (R) was observed. The F₂ segregation explained on the basis of phenotypic expression was further confirmed by F₃ segregation.     

R-41, a sunflower restorer inbred line, carrying two genes for resistance against a highly virulent Spanish population of Orobanche cernua

The inheritance of resistance to a highly virulent population of sunflower broomrape (Orobanche cernua) has been studied in R-41, a Spanish sunflower restorer inbred line. Using the cytoplasmic male-sterile inbred line HA-89 (cms; very susceptible to this population of broomrape) as a female parent, progenies of the cross with R-41, i.e. Fl, F2 and BC1 to both parents, as well as the parental lines, were analysed for their reaction to the broomrape population EC-94. The goodness of fit of the observed vs expected segregation ratios indicated that the inheritance of resistance to broomrape in line R-41 is conferred by two independent dominant genes.     

Inheritance of Dry Root Rot (Rhizoctonia bataticola) Resistance in Chickpea (Cicer arietinum)

The inheritance of resistance to dry root rot of chickpea caused by Rhizoctonia bataticola was studied. Parental F₁ and F₂ populations of two resistant and two susceptible parents, along with 49 F₁ progenies of one of the resistant × susceptible crosses were rested for their reaction to dry root rot using the blotting-paper technique. All F, plants of the resistant × susceptible crosses were resistant; the F₂ generation fitted a 3 resistant: 1 susceptible ratio indicating monogenic inheritance, with resistance dominant over susceptibility. F³ family segregation data confirmed the results. No segregation occurred among the progeny of resistant × resistant and susceptible × susceptible crosses.     

Two genes and linked RAPD markers involved in resistance to Fusarium oxysporum f. sp. Ciceris race 0 in chickpea

The inheritance of resistance to fusarium wilt race 0 of chickpea and linked random amplified polymorphic DNA (RAPD) markers were studied in two F₆:₇ recombinant inbred line (RIL) populations. These RILs were developed from the crosses CA2156 × JG62 (susceptible × resistant) and CA2139 × JG62 (resistant × resistant), and were sown in a field infected with fusarium wilt race 0 in Beja (Tunisia) over 2 years. A1:1 resistant to susceptible ratio was found in the RIL population from the CA2156 × JG62 cross, indicating that a single gene with two alleles controlled resistance. In the second RIL population (CA2139 × JG62) a 3:1 resistant to susceptible ratio indicated that two genes were present and that either gene was sufficient to confer resistance. Linkage analysis showed a RAPD marker, OPJ20600, linked to resistance in both RIL populations, which is present in the resistant parent JG62.     

Inheritance of resistance to race 330 of Plasmopara halstedii in three sunflower lines

Sunflower lines RHA‐274, HA‐61 and RHA‐325 were studied for their resistance to race 330 of downy mildew (Plasmopara halstedii). The same inbred line, with normal (HA‐89) or sterile cytoplasm (cmsHA‐89) was used in all the crosses as susceptible parent, and, in each cross, only one genotype of the resistant parent was studied. The resistant‐to‐susceptible ratios obtained in the BC₁ and F₂ progenies from the crosses of the lines RHA‐274 and HA‐61 to cmsHA‐89 and HA‐89, respectively, suggested that, in each resistant line, two dominant genes are responsible for resistance to this downy mildew race. One of the genes (A) is epistatic to the other (B), and the recessive allele b in homozygosity is also epistatic to aa, with plants carrying aabb genotypes being resistant. Resistance to race 330 seemed to be controlled by two complementary genes in the sunflower inbred line RHA‐325, the dominant allele of one of them being present in cmsHA‐89. In the genotypes HA‐89 or cmsHA‐89, the existence of genes that modify the expected segregations following the crosses with resistant parents is proposed. It is concluded that, although major genes have been described as responsible for monogenic resistance to downy mildew, other types of regulation of this character, such as complementarity and epistatic relationships, do occur.     

Resistance to Sunflower Rust and its Inheritance in Wild Sunflower Species

Resistance to the prevailing races of sunflower rust, Puccinia hehanthi Schw., is lacking in the commercial hybrids (Helianthus annuus L.). The objective of this study was to identify new sources of resistance to the four North American rust races in wild Helianthus species, and to determine their mode of inheritance. Seventy-eight accessions of H. annuus L., H. argophyllus Torrey and Gray, and H. petiolans Nutt. were evaluated in the greenhouse. Resistance to races 1, 2, 3, and 4 was observed in 25, 28, 15, and 26% of the plants, respectively, and 10% of the plants were resistant to all four races. Seven accessions that had a high percentage of resistant plants to all the four races were selected and one resistant plant from each accession was crossed with susceptible inbred line HA89. Three to four F₁ plants resistant to all four races from each cross were backcrossed with HA89. F₁ plants from PI-413118 × HA89 and PI 413175 × HA89 were resistant to all four races. The PI 413023 × HA89 F₁ plants were 100 % resistant to races 3 and 4 and segregated in a 3: 1 resistant (R) to susceptible (S) ratio to races 1 and 2. The other four F₁ combinations segregated 3R: IS ratios to all four races. Bc₁F₁ progenies revealed that plants from PI 413048, PI 413037, PI 413038, and PI 413171 used in the crosses possessed two dominant genes in heterozygous condition for resistance to each of the four races, whereas plants from PI 413023 possessed two dominant genes in heterozygous condition for resistance to each of races 1 and 2, and one dominant resistance gene in homozygous condition for each of races 3 and 4. Plants from PI 413118 and PI 413175 carried a single dominant gene in homozygous condition for resistance against each of the four races.     

Genetics of host reactions to three races of the bacterial pustule pathogen in cowpea

Summary Inheritance of the brown hypersensitive resistant (BHR), non-hypersensitive resistant (R) and susceptible (S) host reactions produced by three races of the bacterial pustule pathogen (Xanthomonas campestris pv. vignaeunguiculatae) was studied in 45 F₁, F₂ and testcross progenies, using the infiltration inoculation method BHR reaction was dominant over R and S reactions, and R was recessive to S reaction. Two genes appeared to be involved in BHR reaction; one governing BHR reaction to race 1 and the other to races 1 and 2. Both were ineffective against race 3. R reaction, effective against all the races, appeared to be controlled by one, two or three recessive genes. One cowpea line had one BHR gene and two duplicate recessive R genes. Reaction expression in the segregants was clear and as expected with races 2 and 3 but was modified with race 1, possibly due to interactions between dominant or recessive alleles of the BHR genes and the homozygous recessive allele of the R genes. Gene symbols Bp-1 and Bp-2 are proposed for the BHR genes and bp-3, bp-4 and bp-5 for the recessive R genes. The genes present in each of the differential cowpea line are suggested.Contribution from the International Institute of Tropical Agriculture, Ibadan, Nigeria and Crop Development Division, Ministry of Agriculture, P.O. Box 9071, Dar es Salaam Tanzania.     

Inheritance of resistance to Verticillium wilt (Verticillium dahliae) in cotton (Gossypium hirsutum L.)

Verticillium wilt, caused by Verticillium dahliae Kleb., is a major constraint to cotton production in almost all countries where cotton is cultivated. Developing new cotton cultivars resistant to Verticillium wilt is the most effective and feasible way to combat the problem. Little is known about the inheritance of resistance to Verticillium wilt of cotton, especially that caused by the defoliating (D) and nondefoliating (ND) pathotypes of the soil‐borne fungus V. dahliae. The objective of this study was to determine the inheritance of resistance in cotton against both pathotypes of V. dahliae. Crosses were made between the susceptible parent ‘Cukurova 1518’ and each of four resistant parents PAUM 401, PAUM 403, PAUM 405 and PAUM 406 to produce F₂ generations in 2002 and F_2:3 families in 2003. Disease responses of parent and progeny populations to the D and ND pathotypes were scored based on a scale of 0‐4 (0, resistant; 4, susceptible). F₂ populations inoculated with the D pathotype showed a 3 : 1 (resistant : susceptible) plant segregation ratio. Tests of F_2:3 families confirmed that resistance was controlled by a single dominant gene. In contrast, analysis of data from F₂‐ and F₂‐derived F₃ families suggested that resistance to the ND pathotype is controlled by dominant alleles at two loci.     

Screening for resistance to broomrape (Orobanche cernua) in cultivated sunflower

Racial evolution of sunflower broomrape (Orobanche cernua) has been very rapid in Spain during recent years, in which resistance has been overcome several times and there has been an important increase in areas infested with this parasitic angiosperm. In order to find resistance to a highly virulent population of sunflower broomrape that could be used directly in breeding programmes, three different sets of cultivated plant material composed of 429 entries were tested by artificial inoculation. All evaluated inbred lines from Moden, Canada, were fully susceptible. Out of the 240 P.I. accessions tested, only 10 segregated for resistance to broomrape, the rest being susceptible. From the 160 USDA breeding lines evaluated, 5% were resistant and 19% segregated for resistance to O. cernua. These lines traced back mainly to crosses of RHA 274 and RHA 801 with Russian, Turkish and Romanian hybrids. The origin of P.I. accessions that segregated for resistance were primarily derived from the former USSR and from Romania.     

新疆阿勒泰地区和内蒙古乌拉特前旗抗列当向日葵品种(系)的鉴定

向日葵列当是向日葵生产中重要的寄生性杂草。新疆阿勒泰地区和内蒙古乌拉特前旗是国内向日葵列当发生的重灾区。为筛选并为抗列当育种工作提供优质抗性材料,从根本上防治向日葵列当,利用田间自然发生向日葵列当的田块,采用随机区组设计设置小区试验;通过寄生率、寄生程度2 个指标判定对列当的抗感性。于2012 年在新疆阿勒泰对56 个向日葵品种（系）,2013—2014 年在内蒙古乌拉特前旗分别对22 个品种（系）和20 个品种（系）,进行抗列当鉴定。结果表明：在新疆22 个油葵品（系）中‘陇葵杂1 号’、‘F08-1’、‘辽丰F53’、‘赤CY101’、‘S26’、‘MGS’、‘S31’等16 个品种,34 个食葵品种（系）中‘JK106’品种,表现为免疫;在内蒙古乌拉特前旗2013—2014 年24 个油葵品种（系）中,‘赤CY102’、‘F08-1’等2 个品种表现为免疫,‘MSG’、‘新葵杂5 号’、‘赤029×115R’、‘赤128A×116R’等4个品种（系）表现为高抗,而18 个食葵品种（系）中,没有免疫品种,只有‘JK103’和‘JK106’表现为抗列当,其余16 个品种（系）均表现为感病和高度感列当。其中油葵品种‘赤CY102’在新疆和内蒙古抗列当鉴定中均表现免疫。在2 个不同地区进行向日葵品种抗列当鉴定,新疆地区表现免疫和高抗的品种较内蒙古地区多,说明内蒙古乌拉特前旗列当生理小种级别高于新疆阿勒泰地区列当生理小种。另外,油葵品种对列当的抗性较食葵高。     

Inheritance of the Powdery Mildew Resistance Mlk in Wheat

The inheritance of the Mlk powdery mildew resistance originating from ‘Heine 2174.50’ was analyzed by crossing the Mlk resistant cultivar ‘Ralle’× cv. ‘Amor’ (highly susceptible) and vice versa and by observing the reactions of F₁- and F₂-plants after inoculation with two different Mlk avirulent powdery mildew isolates. In all cases, a 3 (resistant): I (susceptible) segregation was found in F₂. The reactions of the F₂plants against the two powdery mildew isolates were identical in each case. Therefore, it is supposed that one dominant resistant gene is responsible for the resistant reactions against these two isolates. These results support the earlier assumption of Heun and Fischbeck (1987b) that the whole Mlk resistance pattern is controlled by a single gene.     

A second gene for resistance to race 4 of Fusarium wilt in chickpea and linkage with a RAPD marker

Fusarium wilt caused by Fusarium oxysporum Schlechtend.: Fr f. sp. ciceris (Padwick) Matuo & Sato is a devastating disease of chickpea. The current study was conducted to determine the inheritance of the gene(s) for resistance to race 4 of fusarium wilt and to identify linked RAPD markers using an early wilting line, JG-62, as a susceptible parent. Genetic analysis was performed on the F₁s, F₂s and F₃ families from the cross of JG-62 × Surutato-77. The F₃ families were inoculated with a spore suspension of the race 4 wilt pathogen and the results were used to infer the genotypes of the parent F₂ plants. Results indicated that two independent genes controlled resistance to race 4. Linkage analysis of candidate RAPD marker, CS-27₇₀₀, and the inferred F₂ phenotypic data showed that this marker locus is linked to one of the resistance genes. Allelism indicated that the two resistance sources, Surutato-77 and WR-315, shared common alleles for resistance and the two susceptible genotypes, C-104 and JG-62, carried alleles for susceptibility. The PCR-based marker, CS-27₇₀₀, was previously reported to be linked to the gene for resistance to race 1 in a different population which suggested that the genes for resistance to races 1 and 4 are in close proximity in the Cicer genome. This revised version was published online in August 2006 with corrections to the Cover Date.     

Inheritance of resistance to Fusarium wilt (race 2) in chickpea

The inheritance of resistance to Fusarium wilt (race 2) of chickpea was studied in a set of three crosses, i.e. ‘WR315’בC104’ (resistant × susceptible), ‘WR315’בK850’ (resistant × tolerant) and ‘K850’בGW5/7’ (tolerant × tolerant) in order to investigate the number of genes involved, their complementation and to find out whether resistant segregants are possible in a cross between two tolerant cultivars. Tests of F₁, F₂ and F₃ generations of these crosses under controlled conditions at ICRISAT, Patancheru, India, indicated involvement of three loci (two recessive and one dominant alleles). The homozygous recessive form at the first two loci conferred resistance whereas susceptibility occurred when the first two loci were in the dominant form. A dominant allele at the third locus can complement the dominant alleles at the other two loci to confer tolerance. Occurrence of resistant segregants in a cross between two tolerant cultivars was observed.     

Identification of alleles at two loci controlling resistance to Phomopsis stem blight in narrow-leafed lupin (Lupinus angustifolius L.)

The genetics of resistance to Phomopsis stem blight caused by Diaporthe toxica Will., Highet, Gams & Sivasith. in narrow-leafed lupin (Lupinus angustifolius L.) was studied in crosses between resistant cv. Merrit, very resistant breeding line 75A:258 and susceptible cv. Unicrop. A non-destructive glasshouse infection test was developed to assess resistance in the F₁, F₂, selected F₂-derived F₃ (F_2:3) families, and in selfed parent plants. The F₁ of Unicrop × 75A:258 (and reciprocal cross) was very resistant, and the F₂ segregated in a ratio of 3:1 (resistant: susceptible), which suggested the presence of a single dominant allele for resistance in 75A:258. In Merrit × Unicrop (and reciprocal), the F₁ was moderately resistant, and the F₂ segregated in a ratio of 3:1 (resistant: susceptible). Thus Merrit appeared to carry an incompletely dominant resistance allele for resistance. The F₁ of Merrit × 75A:258 (and reciprocal) was very resistant and the F₂ segregated in a ratio of 15:1 (resistant: susceptible), which supported the existence of independently segregating resistance alleles for resistance in 75A:258 and Merrit. Alleles at loci for early flowering (Ku) and speckled seeds (for which we propose the symbol Spk) segregated normally and independently of the resistance alleles. Resistant F₂ plants gave rise to uniformly resistant or segregating F_2:3 families, whereas susceptible F₂ plants gave rise only to susceptible F_2:3 families. However, the variation in resistance in the F₂ and some F_2:3 families of crosses involving 75A:258, from moderately to extremely resistant, was greater than that expected by chance or environmental variation. We propose the symbols Phr1 to describe the dominant resistance allele in 75A:258, and Phr2 for the incompletely dominant resistance allele in Merrit. Phr1 appears to be epistatic to Phr2, and expression of Phr1 may be altered by independently segregating modifier allele(s). This revised version was published online in July 2006 with corrections to the Cover Date.     

Dominant gene for common bean resistance to common bacterial blight caused by <Emphasis Type="Italic">Xanthomonas</Emphasis><Emphasis Type="Italic">axonopodis</Emphasis> pv. <Emphasis Type="Italic">phaseoli</Emphasis>

The common bacterial blight pathogen [Xanthomonas axonopodis pv. phaseoli (Xap)] is a limiting factor for common bean (Phaseolus vulgaris L.) production worldwide and resistance to the pathogen in most commercial cultivars is inadequate. Variability in virulence of the bacterial pathogen has been observed in strains isolated from Puerto Rico and Central America. A few common bean lines show a differential reaction when inoculated with different Xap strains, indicating the presence of pathogenic races. In order to study the inheritance of resistance to common bacterial blight in common bean, a breeding line that showed a differential foliar reaction to Xap strains was selected and was crossed with a susceptible parent. The inheritance of resistance to one of the selected Xap races was determined by analysis of segregation patterns in the F₁, F₂, F₃ and F₄ generations from the cross between the resistant parent PR0313-58 and the susceptible parent ‘Rosada Nativa’. The F₁, F₂ and F₃ generations were tested under greenhouse conditions. Resistant and susceptible F_3:4 sister lines were tested in the field. The statistical analysis of all generations followed the model for a dominant resistance gene. The resistant phenotype was found to co-segregate with the SCAR SAP6 marker, located on LG 10. These results fit the hypothesis that resistance is controlled by a single dominant gene. The symbol proposed for the resistance gene is Xap-1 and for the bacterial race, XapV1.