Disease Tolerance in Helianthus petiolaris : A Genetic Resource for Sunflower Breeding

Abstract

Argentina is a major sunflower producer in the world, with crop acreage of 2?2.7 million ha in the last four years. Sunflower crop yield is often influenced by sanitary constraints, mainly fungal pathogens. Helianthus petiolaris is a wild species native to North America established in central Argentina displays a high tolerance to a number of fungal diseases and insects. Controlled crosses of this species with sunflower demonstrated that H. petiolaris constitutes a valuable genetic variability source for sunflower breeding to improve tolerance to rust (Puccinia helianthi), white rust (Albugo tragopogonis), verticillium wilt (Verticillium dahliae), powdery mildew (Erisiphe sp.) and the sunflower moth (Rachiplusia nu). This places H. petiolaris in an outstanding position as a genetic resource since different important traits could be transferred to the crop through interspecific hybridization.     

Wild annual Helianthus anomalus and H. deserticola for improving oil content and quality in sunflower

Within the past decade, the desire for alternative sources of fuels, chemicals, and other industrial materials has received increased attention. Sunflower (Helianthus annuus L.) oil has the potential to be improved for nutritional and industrial purposes through selection and breeding. The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from wild species, resulting in a continuous improvement in agronomic traits. The genus Helianthus is comprised of 51 species and 19 subspecies with 14 annual and 37 perennial species. Interest in using wild species in breeding programs has increased, but concerns about the introduction of low oil concentration and quality from the wild species persist. Two annual desert species, Helianthus anomalus Blake and H. deserticola Heiser, are excellent candidates for increasing oil concentration and enhancing quality based on their adaptation to desert environments. The objective of this study was to collect achenes of H. anomalus and H. deserticola from the desert southwest USA and assess their potential for improving oil concentration and quality in cultivated sunflower. The sunflower collection took place from 16 to 23 September 2000 and covered a distance of 4100 km in three states: Utah, Arizona, and Nevada. The only H. deserticola population collected had an average oil concentration of 330 g/kg, whereas the two populations of H. anomalus had an oil concentration of 430 and 460 g/kg, the highest concentration recorded in any wild sunflower species. The linoleic fatty acid concentration in the oil of H. anomalus populations was uncharacteristically high for a desert environment, approaching 700 g/kg. A linoleic acid concentration of 540 g/kg in H. deserticola was more typical for a desert environment. H. anomalus has the largest achenes and the highest oil concentration of any wild sunflower species, and the same chromosome number (n = 17) as cultivated sunflower. These features will facilitate the introduction of genes from this wild annual progenitor into cultivated sunflower. The lower saturated fatty acid profile in this species is also a desirable trait offering the potential to reduce saturated fatty acids in cultivated sunflower. Further research will be needed to determine the inheritance of the fatty acids and oil concentration. Other agronomic traits will need to be maintained during the introgression of these traits into cultivated sunflower oil.     

Simulation for response of crop yield to soil moisture and salinity with artificial neural network

In saline fields, irrigation management often requires understanding crop responses to soil moisture and salt content. Developing models for evaluating the effects of soil moisture and salinity on crop yield is important to the application of irrigation practices in saline soil. Artificial neural network (ANN) and multi-linear regression (MLR) models respectively with 10 (ANN-10, MLR-10) and 6 (ANN-6, MLR-6) input variables, including soil moisture and salinity at crop different growth stages, were developed to simulate the response of sunflower yield to soil moisture and salinity. A connection weight method is used to understand crop sensitivity to soil moisture and salt stress of different growth stages. Compared with MLRs, both ANN models have higher precision with RMSEs of 1.1 and 1.6 t ha⁻¹, REs of 12.0% and 17.3%, and R² of 0.84 and 0.80, for ANN-10 and ANN-6, respectively. The sunflower sensitivity to soil salinity varied with the different soil salinity ranges. For low and medium saline soils, sunflower yield was more sensitive at crop squaring stage, but for high saline soil at seedling stage. High soil moisture content could compensate the yield decrease resulting from salt stress regardless of salt levels at the crop sowing stage. The response of sunflower yield to soil moisture at different stages in saline soils can be understood through the simulated results of ANN-6. Overall, the ANN models are useful for investigating and understanding the relationship between crop yield and soil moisture and salinity at different crop growth stages.     

Occurrence of Alternaria leaf blight of sunflower caused by two closely related species Alternaria solani and A. tomatophila in Inner Mongolia

Sunflower (Helianthus annuus L.) is an important oilseed crop in China and is grown in rotation with potato in the northern parts of China, including Inner Mongolia, Hebei, Shaanxi, Shanxi, Gansu, Jilin, Liaoning and Heilongjiang provinces. In 2014, diseased samples of sunflower (variety 3638C) with black sunken lesions on bracts and stems of sunflower were collected in Wuchuan, Hohhot (41°05′ N, 111°27′ E) and Chahaeryouyihouqi, Wulanchabu (41°52′ N, 113°0′ E), Inner Mongolia, China. We used morphological and molecular techniques to identify the causal agent of Alternaria leaf blight. Phylogenetic analysis based on a combined phylogenetic dataset using the glyceraldehyde-3-phosphate dehydrogenase (gpd) and Alternaria major allergen gene (Alt a1) was done to support the morphological identification. In addition, PCR was performed with specific primers targeted on Alt a1 and calmodulin genes of A. solani and A. tomatophila. The results showed that HaAs7 gave an amplicon of the expected size (164 bp) with A. solani-specific primers, however, no band was observed with the A. tomatophila-specific primers. The opposite pattern of PCR result (483 bp) was obtained with DNA of HaAt4 as template, indicating that HaAs7 is A. solani and HaAt4 is A. tomatophila. Furthermore, evaluation the pathogenicity of the recovered Alternaria isolates and their potential as causal agents of Alternaria leaf blight of sunflower was done. Pathogenicity tests showed that A. solani and A. tomatophila tested could be capable of causing Alternaria leaf blight of sunflower. Till now, nine species of Alternaria have been reported causing Alternaria leaf blight of sunflower, this is the first report that A. solani and A. tomatophila as causal pathogens for Alternaria leaf blight on sunflower.     

Increasing Crop Competitiveness to Weeds Through Crop Breeding

Abstract

Increasing the ability of crops to compete against weeds, through either enhancing crop tolerance or crop interference to weeds, provides an attractive addition to current weed control practices and could be an integral component of weed management systems. Research has shown that considerable variability exists among crop culti-vars with respect to their ability to compete with weeds. Despite this evidence, directed research on competitive crops has been minimal. Reasons for this lack of emphasis in plant breeding programs include the effectiveness of current weed management with tillage and herbicides, and the lack of easily identifiable crop characteristics that are indicative of weed competitiveness. Expanded knowledge of specific crop-weed interactions would facilitate crop competitiveness to weeds through either crop management practices or plant breeding. Plant breeders need basic and applied information to identify favorable crop-weed competitive traits in order to enhance or incorporate those traits into crop cultivars. Accelerated research on weed competitive crops should lead to more economical, effective, and feasible integrated weed management programs for all crops.     

Agronomic performance of rice breeding lines selected based on plant traits or grain yield

Selection for yield per se has greatly contributed to yield improvement in many crops. It is expected that selection based on plant traits is more effective in increasing crop yield potential. This study was conducted to compare the effectiveness of trait-based and yield-based selection in increasing rice yield and to determine whether lines with ideotype traits have the potential to express higher yield under optimal crop management conditions. Lines were selected based on plant traits or on grain yield measured in a breeder's replicated yield trial. The main target traits for selection were plant height, leaf and panicle morphology, grain size, total dry weight, and grain-filling percentage. Yield performance of trait-based selection was compared with that of yield-based selection in an agronomic trial with optimum crop management for three seasons. Trait-based selection increased leaf area index and total dry weight but reduced spikelet number per m² and harvest index compared with yield-based selection. Consequently, selection based on plant traits did not increase grain yield compared with selection based on yield per se. In one of the three seasons, yield of trait-based selection was significantly lower than that of yield-based selection. Among all tested breeding lines, maximum yield was produced by yield-based selection and minimum yield came from trait-based selection. These results suggest that lines with ideotype traits did not express higher grain yield than lines selected based on yield per se under optimal crop management conditions, and yield-based selection was as effective in increasing rice grain yield as trait-based selection in the late generations of the breeding cycle.     

Lesquerella: New crop development and commercialization in the U.S.

While Lesquerella fendleri Gray (Wats.) is not yet a commercial crop, its history serves as a model for new crop development. The most important characteristic is the absence of any significant biological barriers to commercialization. Other potential crops may have valuable, high-demand products but possess traits difficult to overcome such as seed shattering or poor yield capacity. Lesquerella has a distinctive plant architecture that is conducive to seed productivity under a variety of conditions, and the trait could be further exploited. The plant also has high amounts of within-species and interspecific genetic diversity allowing breeding improvements in traits including oil quantity and quality. The unique seed oil is predominately composed of a hydroxy fatty acid, lesquerolic acid (C20:1OH), that is similar to ricinoleic acid (C18:1OH) found in castor oil. Improvements in agronomics will help increase seed yields, water use efficiency, while reducing crop production costs. New tools offered by remote sensing will help plant breeders and growers assess crop development. Defining herbicides and obtaining registrations for use in lesquerella appears to be the biggest obstacle for commercialization of this crop. The improvements in agronomics, breeding, genetics, and the expansion of new markets started in the 1980's, and has made lesquerella a viable potential crop that could utilize thousands of hectares in arid climates of the world provided research continues.     

Root lodging in sunflower. Variations in anchorage strength across genotypes,soil types,crop population densities and crop developmental stages

Root lodging is an important adversity affecting sunflower (Helianthus annuus L.) production in Argentina under current husbandry practices, and may limit progress towards the achievement of higher yields via increased plant population density. Although there are perceptions that lodging susceptibility varies across developmental stages, crop population densities, genotypes and soil types, these perceptions have not been tested for sunflower using a standardized experimental protocol. This study aimed at: (1) identifying the sources of the variation in root lodging susceptibility in response to variations in crop population density in two genotypes of reputedly different susceptibility; (2) detecting the crop developmental stages most susceptible to root lodging; and (3) examining the relationships between root failure moment, root plate diameter and soil shear strength. We mechanically induced lodging at three developmental stages in plants rooted in pre-wetted plots. The crops were grown at 5.6 plants m⁻² over 3 years on either Typic Argiudoll or Typic Hapludoll soils and at 3, 5.6, 10 and 16 plants m⁻² on a Typic Argiudoll. The force needed to induce root lodging (root failure moment) and root plate diameter varied across genotypes, plant densities and developmental stages. Root failure moment and root plate diameters were greater (p < 0.05 for both variables) in the resistant hybrid across the three development stages and almost all crop population densities. For both hybrids, the most susceptible development stage was R2, and root failure moment and root plate diameter diminished (p < 0.05) as crop population density increased. Although root failure moment did not differ between soil types, root plate diameter was greater (p < 0.0001) in the coarser soil. The relationship between root failure moment and the product of root plate diameter cubed by soil shear strength (a measure of plant anchorage strength) for both hybrids, both soil types, and all crop population densities could be described by a single linear relationship (y = 0.2382x; R² = 0.812; p < 0.025).     

Comparison of the potential of organophosphorous insecticides and soaps in conifer aphid control

A comparison of the toxicity to two aphids, Elatobium abietinum and Adelges cooleyi, and a coccinellid predator, A. obliterata, of dimethoate, fenitrothion and malathion with Safer's insecticidal soap (SIS) and saponified corn oil and sunflower oil confirmed that the organophosphates were more toxic. This did not detract from the effectiveness of the soaps under field conditions provided that appropriately higher concentrations were applied. SIS was not more toxic to the insects than the saponified oils with corn oil soap, which is rich in oleic and linoleic acid, frequently producing higher insect mortality levels. In E. abietinum a linear relationship was demonstrated between insecticide susceptibility and aphid instar, with late instars apparently becoming progressively more susceptible. This relationship disappeared when LC₅₀ values were corrected for size differences. Larval Aphidecta obliterata were more susceptible than adults and field applications of these chemicals should be timed to avoid the larval feeding period. Phytotoxic symptoms appeared on Sitka spruce needles after application of sunflower oil soap, current year needles being particularly susceptible to damage. Corn oil soap or SIS could be substituted during this susceptible period.     

Wheat transformation: current technology and applications to grain development and composition

Transgenesis is a powerful research tool that can be adapted to investigate many aspects of gene function. It has been used widely in model plants such as Arabidopsis, tobacco and rice but until recently, bottlenecks in DNA-delivery and tissue culture meant that it could not be used routinely for wheat research. However, many aspects of grain development and composition are unique to wheat and cannot be easily investigated in model species. Over the last decade, progress in biolistic- and Agrobacterium-mediated DNA delivery, reduction in genotype-dependency in wheat tissue culture and in the development of a range of supplementary technologies has enabled its application in this traditionally recalcitrant crop. The use of genetic modification has already made a significant impact on our understanding of interactions between high molecular weight glutenin subunits and their individual contribution to dough strength. As candidate genes become available the application of genetic transformation is set to play a major part in the elucidation of their function in determining other important grain traits such as starch and lipid composition, dietary fibre composition and grain texture.     

Morphological traits and allocation patterns related to stress-tolerance and seed-yield in wild and domesticated evening primrose (Oenothera L. Onagraceae)

Wild evening primrose species (Oenothera spp.) native to Argentina, have been suggested as a new crop for irrigated valleys of semi-arid Patagonia. This paper describes patterns of biomass allocation, morphological traits related to stress-tolerance and seed-yield in four species of Oenothera grown in a common garden at three plant densities. Wild and domesticated species are compared. The effect of resource availability on those traits during three phenological stages (vegetative, reproductive and maturity) is described. Native species were characterized by traits related to stress-tolerance (high root allocation and low specific leaf area) during the vegetative stage. This suite of traits resulted in low biomass accumulation and low seed-yield. The domesticated O. biennis was characterized by a combination of traits related to stress-tolerance (low specific leaf area) and high productivity (high leaf allocation and leaf area ratio and low root allocation). Domesticated species accumulated more biomass than natives. Total biomass and total non-structural carbohydrates present in roots were positively correlated to seed-yield.Oenothera biennis showed the highest seed-yield, although this species showed yield instability in response to changes in the environmental quality. No changes in seed-yield in response to plant density were recorded for either O. lamarckiana or native species. Oenothera biennis showed an optimum density of 20 plants m⁻² and yielded 260 g m⁻², a seed-yield similar to that reported in other countries. Low seed-yield of native species is major drawback that must be overcome. Improving seed-yield in these species could be possible by selection oriented to increase total biomass. Since no detrimental effect of density was found in O. lamarckiana and natives, a higher plant density might increase yield production per unit area.     

不同品种酿酒高粱在盐碱地种植的适应性研究

盐碱地适盐种植是目前发展盐碱地产业的重要模式。以3个酿酒高粱品种为研究对象,通过测定并分析酿酒高粱的农艺性状、产量及籽粒品质等指标,筛选出耐盐、优质高产的酿酒高粱品种以丰富河套灌区作物的种植结构,降低因长年种植葵花引起各种病虫害的发生,并提供优质酿酒原料。研究结果表明:1)吉杂127的产量最高,为10 832.0 kg/hm^2,其次是辽杂19的10 429.8 kg/hm^2;2)辽杂19农艺性状、产量及籽粒淀粉、蛋白质含量和容重等指标优于其他品种,为最佳酿酒高粱品种;3)相比于种植葵花,种植高粱具有机械化程度高、便于轮作倒茬等优点,提高种植户的净收入约5070元/hm^2,并能提供优质酿酒原材料。     

Economic considerations of mouse-plague control in irrigated sunflower crops

During a localized plague of the house mouse (Mus musculus) the population within an irrigated sunflower crop was estimated to be 2716 mice/ha 7 weeks before harvest. These mice were estimated to have caused a reduction of 12·4% of the expected yield up to that time. The crop was then subjected to a variety of control techniques, the most successful of which resulted in a reduction of 90% in the mouse population. Using 3·4 g/day as the amount of sunflower seed each mouse would consume or damage it was estimated that a 90% effective control programme would result in an increase of 20·4% in the harvested yield. Similar estimates for other irrigated grain crops indicate that mouse-plague control is an economically sound proposition.     

Responses to short-term waterlogging during grain filling in sunflower

Higher than normal rainfall during grain filling of sunflower (Helianthus annuus L.) has been shown to be associated with reductions in grain yield. This yield loss has been variously attributed to low radiation (cloudy weather) or to the increased incidence of diseases. Impaired physiological processes directly linked to transient waterlogging arising from excess rainfall could also reduce yield. The aim of this work was to evaluate the existence and nature of physiological responses to waterlogging in sunflower.     

Short internode,double podding and early flowering effects on maturity and other agronomic characters in chickpea

Chickpea is an indeterminate species, which continues to flower and set new pods over a long period under wet and cool growing conditions, resulting in excessive canopy development and delayed maturity. We hypothesized that the chickpea's long season requirement could be reduced through introgression of short internode, double podding and early flowering. Four populations E100Ym/CDC Anna, 272-2/CDC Anna, 298T-9/CDC Anna, and 298T-9/CDC Frontier were developed to test this hypothesis with the first parents of each cross being the donor of the short internode, double podding and early flowering traits, respectively. Also, the donor parents E100Ym, 272-2 and 298T-9 were intercrossed. Segregating populations of F₂ to F_3:6 generations were then evaluated under greenhouse and field conditions. When expressed well, double podding significantly reduced time to maturity as compared to the single podding counterparts. The best double podding lines were about 1 week earlier maturing than the early parent and standard checks. Days to flowering (DF) was positively associated with days to maturity (DM) (r = 0.44, P < 0.001), and partial path analysis revealed that DF contributed to DM mainly via days to first pod maturity (DFPM). In the two early flowering populations 298T-9/CDC Anna and 298T-9/CDC Frontier, DF determined about 32% of the variation in DFPM. Conversely, the short internode trait had an undesirable effect, in that all the short internode segregants were too late to mature. In conclusion, the alleles for double podding and early flowering may be used to improve early maturity in chickpea and subsequently minimize the risks associated with the production of this crop in environments where the growing conditions allow excessive crop canopy development, as in the Canadian prairies.     

油料作物品质相关性状全基因组关联分析研究进展

油料作物是人们日常生活中必不可少的食用油及营养来源之一。随着人们对食用油品质要求的提高，品质性状成为近年来油料作物品种选育的重要育种目标之一。品质性状是一种复杂的数量性状，所以传统育种选育效率低，周期长。然而，基于连锁不平衡原理的全基因组关联分析为挖掘多基因控制的数量性状候选基因提供了新的途径。目前由于其定位精度高、广度大、周期短等优点已经在许多作物上得到了应用。本文对全基因组关联分析在揭示大豆、油菜、花生、芝麻、胡麻、向日葵等几种重要油料作物的含油率、脂肪酸、蛋白质含量等品质相关性状中的研究进行了总结，并对目前研究存在的不足进行了剖析，最后对未来发展趋势进行了展望，旨在为今后利用GWAS解析各种油料作物品质相关性状的遗传基础及选育高品质油料作物材料提供理论依据和参考。     

Relations between summer crops and ground cover legumes in a subtropical environment 3. Soil water use under sorghum and sunflower

Vigna trilobata (L.) Verdc. and Medicago scutellata L. are short herbaceous legumes that help to reduce soil erosion when grown in association with row crops in the sub-humid/semi-arid subtropics. Soil water use and root distribution beneath sorghum (Sorghum bicolor (L.) Moench) and sunflower (Helianthus annuus L.) with and without V. trilobata were measured on a vertisol in South East Queensland. Sorghum was sown in October and January at densities of 10 and 5 plants m⁻² and sunflower at densities of 5 and 2.5 plants m⁻². V. trilobata seed was broadcast at 150 seeds m⁻². Pure stands of V. trilobata and M. scutellata were also sown.Soil profiles were uniformly wet to at least 2 m depth at each sowing date and remained so for the first 40 days of each growth cycle. Thereafter profiles dried rapidly over the next 40 days, providing opportunities for assessing soil water use. Subsequent rain restored and sustained profile water content until crop maturity.Undersown V. trilobata hastened soil drying, resulting in the extraction of 21 mm more water by maturity of the October sown crops. In pure stands, V. trilobata extracted water at the same rate as sunflower from the top 1.0 m of the soil profile, but not from the deeper layers. However, pure stands of M. scutellata extracted much less soil water than V. trilobata, with negligible extraction from below 0.8 m. Sunflower extracted 48 mm more water than sorghum in the January sowing because it had more roots and extracted more water from below 1.4 m.The capacity of V. trilobata to grow deep roots allows it to compete strongly for soil water and decrease yield of the main crop. Thus, a shallow-rooting plant would be preferred as a ground cover.     

Effect of crop management on epidemics of phomopsis stem canker (Diaporthe helianthi) for susceptible and tolerant sunflower cultivars

Phomopsis stem canker (Diaporthe helianthi) is a worldwide fungal disease which is responsible for high yield losses in sunflower crop in the main regions of production. Field data on the influence of crop management on the incidence and severity of stem canker were reported by Debaeke et al. (2003) but a more thorough study was required to analyse step-by-step the spread of the fungus within the canopy from spore deposition on leaves to stem injury.In a 2-year study (2000–2001), the effects of crop management (plant density, N fertilization, and irrigation) and genotypic tolerance (susceptible vs tolerant cultivars) on the epidemics of Diaporthe helianthi were monitored under conditions of reinforced inoculum. The incidence and severity of leaf and stem symptoms were closely related to canopy development (leaf area index) and microclimatic conditions (relative humidity) resulting from different crop management options. Increasing plant density resulted in a greater proportion of girdling stem lesions, detrimental to yield, because of earlier infection under dense canopies. The number of girdling lesions per plant was maximal with high N fertilization but more leaves were infected without N fertilization.The field data were used to evaluate satisfactorily the epidemiological Asphodel model regarding the main periods of leaf infection. The relative humidity within the canopy (observed), the number of leaf infection events (simulated by Asphodel) and the final proportion of stem lesions (observed) were positively related which clearly demonstrated the key role of crop management in the development of stem canker in sunflower.     

Model legumes contribute to faba bean breeding

Faba bean is an excellent candidate crop to provide nitrogen input into temperate agricultural systems. However, its growth is hampered by several factors including environmental stresses and the presence of anti-nutritional factors. To solve these limitations, breeding programs have been initiated that were successful for monogenic traits but not so for multigenic traits. The large genome size of faba bean has slowed down breeding processes. Several other legumes have emerged as model legumes including Medicago truncatula, Lotus japonicus, Glycine max and Pisum sativum. The establishment of these models has already boosted our understanding of important processes such as the nitrogen-fixing symbiotic interaction. The high level of synteny and collinearity existing between legumes makes possible the transfer of key knowledge from model legumes to faba bean. Here we review the most recent knowledge gained from model legumes on grain quality, resistance to biotic and abiotic stresses, nitrogen-fixing symbiosis and how this knowledge can be employed for faba bean breeding.