Evaluation of Differential Lines and a Collection of Sunflower Parental Lines for Resistance to Broomrape (Orobanche cernua) in Spain

Broomrape (Orobanche cernua Loelf.) is a sunflower parasite which has become a potential threat to this crop in Spam with an increasing incidence in recent last years. In order to investigate the racial situation of the parasite in Spam and to evaluate the resistance of differentials and inbred lines currently used in breeding programmes, two experiments were carried out. In the first, two sets of European sunflower differentials were inoculated with three broomrape populations from different geographical origin. The second experiment studied the reaction to the parasite of 38 inbred lines in comparison with resistant and susceptible checks. Reactions of differential lines resistant to known European broomrape races ranged from complete immunity of lines P-1380-2A and ‘Jdanovski 8281’ to complete susceptibility of ‘Record’ and the universal suscepts. These results confirmed the existence of several physiological races of broomrape in Spain and a different racial composition from that of Eastern Europe. Results from the second experiment showed good resistance of half the restorer lines tested and 36 % of the maintainers and cms lines. This material together with the resistant differential lines constitutes good starting material to be used in developing cultivars resistant to broomrape populations in Spain.     

Inheritance of resistance to phomopsis (Diaporthe helianthi) in sunflower

The inheritance of resistance of sunflower to phomopsis (Diaporthe helianthi) was studied on 10 inbred lines representing a range of resistance and susceptibility levels, and 25 hybrids from a factorial cross of these lines. Analyses of observations over a 3-year period, of semi-natural infection (presence of stem lesions greater than 5 cm) on the hybrids indicated that additive gene control was predominant, with no significant interactions between parental effects. Correlations between infection of parental lines and the mean of their hybrids were not always significant, with certain inbreds which appeared quite susceptible giving hybrids with good levels of resistance. In order to predict hybrid values, it appears necessary to determine the general combining abilities of parental lines. Some inbreds gave very high levels of resistance, others gave very high levels of susceptibility. A test measuring the rate of extension of D. helianthi mycelium on leaves was significantly correlated with the results of natural infections. In particular, it permitted distinction of the most susceptible genotypes, and thus could be used in first generations of breeding to eliminate the most susceptible plants.     

Resistance in the leaf and stem of sunflower after infection with two isolates of Phomopsis

Phomopsis helianthi (sexual stage Diaporthe helianthi) is a major disease in most sunflower growing countries. The objectives of this study were (1) to investigate whether resistance to Phomopsis differs between the leaf and stem tissue and (2) to examine the genetic variation for resistance to Phomopsis in sunflower inbreds. A set of 16 inbred lines was tested using artificial leaf infection with mycelial explants. The lines were screened for their reaction on leaf and stem in four environments to a French Phomopsis isolate and in two environments to a Yugoslavian isolate. Significant genetic variance and mostly high genetic ratios (analogous to heritability) were found for all resistance traits. While fungal growth reflected resistance to Phomopsis in the leaf, petiole score was associated with leaf length. Stem lesion proved to be the most suitable trait for evaluating resistance in the petiole-stem passage. No correlation existed between resistance in the leaf and stem, suggesting that both resistance factors are inherited independently. Both isolates resulted in similar resistance rankings of the inbreds and no difference in their aggressiveness was detected with regard to leaf resistance. Screening for Phomopsis consisting of several steps is recommended, beginning with petiole score or fungal growth to select the most susceptible plants in the early testing, and measuring stem lesion in further generations of breeding.     

A Greenhouse Method to Assess Sunflower Resistance to Sclerotinia Root and Basal Stem Infections

A method was developed to assess sunflower resistance to sclerotinia root infections in greenhouses. Some of the genotypes were also tested in the field to validate the greenhouse testing method. Efficiency of this method was also tested in a diallel cross. The susceptibility could be assessed by the final percentage of dead plants or by the time required to reach a given threshold of attack (threshold latency parameter). The correlation coefficients between susceptibility assessed in the field and with the greenhouse method were significant. The diallel cross analysis indicated that only additive effects are important. Correlation for susceptibility to sclerotinia wilt, between parental lines and the mean of their hybrids, was significant. It is concluded that breeding programmes for increase of resistance to sclerotinia root and basal stem attacks, using the described testing method, should be effective.     

Inheritance of White Rust Resistance in Brassica juncea

Inheritance of white rust resistance was studied in two crosses between resistant (R) and sensitive (S) types of Brassica juncea, namely EC 12749 בParkash’ (R × S) and EC 12749 בVaruna’ (R × S) under conditions of normal and late sowing. Analysis of six generations revealed the importance of additive, dominant and epistatic effects. Disease was more prevalent under late sowing due to favourable environment. Reciprocal recurrent selection is advocated for exploiting the additive and non-additive gene effects for resistance to white rust.     

Association between sporophytic reaction to Alternaria helianthi and gametophytic tolerance to pathogen culture filtrate in sunflower (Helianthus annuus L.)

Seven sunflower genotypes comprising of populations and hybrids showing differential sporophytic reaction to Alternaria leaf and stem blight were studied for their gametophytic reaction to pathogen culture filtrate. The sunflower pollen grains germinate well in the liquid medium and give good pollen tube growth in the absence of the culture filtrate. The addition of increasing concentrations of culture filtrate to medium significantly reduced the pollen germination and tube growth in all the genotypes. The reduction in pollen germination and tube growth in vitro due to culture filtrate was more in highly susceptible genotypes L-101 and Morden than the moderately resistant genotypes Acc. nos. 1229, 180 and ISFH-306. Pretreating the stigma and style with the culture filtrate before pollination reduced the number of pollen grains germinating compared to untreated control suggesting toxin stress can be created on the stigmatic surface before pollination. There was correspondence between pollen germination on stressed stigma (in vitro) and sporophytic reaction of the genotype suggesting pollen grain having resistance would germinate on the stressed stigma and fertilise the ovule achieving selective fertilisation. The correlation analysis indicated that there is a negative relation between sporophytic per cent disease index value and gametophytic parameters such as in vitro and in vivo pollen germination, culture filtrate required to inhibit 50% pollen germination and pollen tube growth. The association between pollen and the sporophytic reaction to the disease indicate the possibility of rapid screening of a large number of genotypes by means of pollen assay as an alternate technique with regard to sporophytic disease index in sunflower. The study also indicate the possibility of pollen selection before fertilisation to achieve rapid improvement in disease resistance. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.     

陕农78抗条锈性遗传规律分析

通过对抗条锈病品种陕农78与感病品种铭贤169 杂交获得的F1代、F1代自交获得的F2代、及F1与铭贤169回交获得的BC1代植株,在人工控制条件下,利用条锈病菌优势生理小种条中31、条中32对苗期进行人工接种后的反应型分析认为：陕农78对条中31的抗性是由1对隐性基因所控制;陕农78对条中32的抗性是由2对隐性基因互作所控制。     

甘蔗(Saccharum species hybrid)种质资源褐锈病和黄锈病抗性位点分子检测

开展种质资源抗锈病分子检测,对甘蔗筛选抗性资源和抗锈病育种具有重要意义。本研究利用已报道的褐锈病抗性位点Bru1和黄锈病抗性位点G1对中国甘蔗育种中的亲本资源和创新材料进行分析。在164份材料中共检测到‘粤糖07-913’、‘桂糖02-281’、‘赣南05-352’等23份带有Bru1抗性标记的材料,占参试材料的14%。在180份材料中共检测到‘粤糖96-86’、‘桂糖03-8’、‘赣南81-1035’等10份带有黄锈病抗性位点G1的材料,占参试材料的5.56%。‘粤糖96-86’、‘ROC16’、‘ROC22’等6份材料同时带有Bru1和G1位点,可能兼具褐锈病和黄锈病两种抗性。本研究结果可为选择优异抗锈病基因资源,开展杂交育种提供科学依据。     

小麦抗源兴资9104抗条锈性遗传研究初报

采用常规杂交和基因推导法相结合,在苗期和成株期对小麦优良抗病种质兴资9104进行抗条锈性遗传研究。结果表明,兴资9104至少含有1对显性全生育期抗条锈病基因和1对成株抗条锈病基因,分别控制对条锈菌生理小种条中17号的全生育期抗性和对条中32号的成株期抗性。兴资9104可能携带有YrSK基因。建议在小麦抗病育种中     

Inheritance of resistance to sunflower downy mildew races 1, 2 and 3 in cultivated sunflower

Sunflower downy mildew (SDM) caused by Plasmopara halstedii, is a major disease of sunflower. Eleven resistance genes have been identified, but allelic relationships among these genes are not clear. This study examined the inheritance and allelic relationships of genes conferring resistance to SDM races 1, 2 and 3 (virulence phenotypes 100, 300 and 700, respectively) and confirmed a twelfth resistance gene. Three USDA Plant Introductions, AMES 3235, PI 497250, and PI 497938, and three released lines, RHA 266, RHA 274 and DM‐2 were studied. RHA 266 has only the Pl₁ gene for race 1 resistance. Digenic inheritance of resistance was found in AMES 3235, PI 497250, and RHA 274. These lines have the Pl₁ and Pl₁₂ genes, conferring resistance to race 1, and the Pl₂ and Pl₁₁ genes, conferring resistance to race 2. DM‐2 and PI 497938 have Pl₁₂ (but not Pl₁ for resistance to race 1, the Pl₁₂ gene (but not the Pl₂) for resistance to race 2, and Pl₅ for resistance to race 3. These resistance genes will serve as a foundation for future gene designations and genetic diversity studies of resistance to SDM.     

Genes for Resistance to Yellow Rust in Seedlings of Wheat Cultivars from Pakistan Tested with British Isolates of Puccinia striiformis

Seedlings of 26 wheat caltivars from Pakistan were tested with 18 British races of P. striiformis. It is postulated that the race-specific genes Yr6, Yr7, Yr9 and perhaps Yr2 were present among the cultivars, and that there was other resistance not controlled by these genes.     

菊花白锈病抗性标准及人工离体接种鉴定方法的优化

为使菊花白锈病的抗性鉴定在可控条件下进行,本文将目测观察与显微镜检方法相结合,制定了菊花白锈病6级抗性鉴定标准,并优化了人工离体接种方法。结果表明,培养瓶内茎段扦插法、培养皿内平铺叶片法均可用于菊花白锈病的离体鉴定;培养瓶内茎段扦插法优于培养皿内平铺叶片法,是最佳的人工离体接种鉴定方法。该优化方法是评价菊花白锈病抗性的既安全又简单的接种方法。     

Influence of Sowing Dates on Yield and Oil Quality in Sunflower

Effect of sowing dates (temperature regimes) on growth, yield oil content and quality in sunflower ( Helianthus annuus L. ) was studied. Plants of early sowings which had received low temperature during 0–45 days of growth grew very poorly in height. Plant height significantly correlated with temperature at all the three growth stages. Plants sown in March produced highest yield and January sown plants recorded lowest yield. Protein content of seeds decreased where as the oil content increased with delay in sowing dates. Oil content in the seeds collected from different sowing dates showed significant differences. However, oil content was not significantly correlated with temperatures at any growth stages. Incorporation of ¹⁴C-acetate into lipids of developing seeds was increased as the sowing was delayed. Early sown plants had higher percentage of oleic acid and late sown plants had higher percentage of linoleic acid. Effect sowing dates on oil content and oil quality were discussed on the basis of temperature variation during different growth stages.     

基于转录组测序的向日葵对干旱胁迫及复水差异表达分析

为研究向日葵在不同程度干旱胁迫下基因的表达调控模式,对抗旱自交系(17062)和非抗旱自交系(167072)分别进行干旱胁迫0、4、8、12、16 d以及复水处理,本研究设置干旱胁迫第8天、第16天以及复水处理与各梯度的对照组进行转录组测序分析。共设有6个差异分组,经过测序共得到277.31G的Clean data,Q30碱基>91%,平均GC含量为45.37%。样品间进行差异基因筛选,得到的DEG数量分别为2365、2571、3149、2692、4593、4980。对各差异基因进行GO和KEGG功能注释,GO分析表明,6个比较组参与生物过程差异基因较多,参与细胞组分的次之,参与分子功能的较少;KEGG分析表明干旱胁迫对向日葵的植物激素信号转导、蔗糖与淀粉代谢、氨基酸代谢有较大的影响,对生理特性的测定显示可溶性糖和可溶性蛋白与正常供水相比具有上升趋势,表明在逆境胁迫下,植物会通过对基因的表达调控的调节来改变相关生理生化代谢途径。本研究通过对向日葵叶片进行转录组分析,对揭示抗旱分子机制及相关代谢途径具有重要意义。     

Inheritance of resistance to anthracnose caused by Colletotrichum capsici in Capsicum

Inheritance of resistance to anthracnose caused by Colletotrichum capsici (Syd.) Butler & Bisby was studied in interspecific Capsicum populations derived from a cross between a Thai elite cultivar Capsicum annuum L.‘Bangchang’ and a resistant line C. chinense Jacq.‘PBC932′. The resistance was assessed by measuring lesion area per fruit area (LFA) on detached chili fruits, using a laboratory‐based injection inoculation. Nil symptoms resembling the resistant parent ‘PBC932’ were also identified in the progeny F₂ and BC1 populations. Segregation of resistance (nil LFA) and susceptibility in the F₂ fitted a 1: 3 Mendelian ratio, indicating that resistance was responsible by a single recessive gene. The segregation of the trait in the testcrosses in both BC1s also confirmed the 1: 3 gene segregating model as found in the F₂.     

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.     

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.     

Inheritance of high palmitic acid content in the sunflower mutant CAS-12 and its relationship with high oleic content

CAS‐12 is a sunflower mutant with increased levels of palmitic (C16: 0 = 30%) and oleic (C18: 1 = 55%) acids in its seed oil, hence it has a reduced linoleic acid content (C18: 2 < 5%). This study was conducted to determine the inheritance of high C16: 0 content and its relationship with high C18: 1 content in CAS‐12. Reciprocal crosses involving CAS‐12, CAS‐5 (high C16: 0 content), HAOL‐9 (high C18: 1 content) and HA‐89 (standard fatty acid profile) were made. The F₁, F₂ and BC₁F₁ generations were obtained. The genetic control of the high C16: 0 trait in CAS‐12 was partially recessive and gametophytic. In all cases, this character segregated in the ratio 19: 38: 7 (low: intermediate: high C16: 0 content) in the F₂ generation. These results, together with the lack of segregation for C16: 0 content in crosses between CAS‐12 and CAS‐5, indicated that the genetic control of the high C16: 0 trait in CAS‐12 was similar to that in CAS‐5 in being controlled by partially recessive alleles (p1, p2, and p3) at three loci. Crosses between HA‐89 and CAS‐12, and HAOL‐9 and CAS‐5 (segregating for C16: 0 and C18: 1) demonstrated that the high C16: 0 and the high C18: 1 traits were independently inherited. However, C18: 1 segregation in these crosses exhibited reversal of dominance. Apparently, the low C18: 1 parental lines carried modifier genes causing the deviation.