Helianthus Mollis Research Articles

White-tailed deer (Odocoileus virginianus) and fire effects on flowering diversity of tallgrass prairie forbs

We studied the effect of white-tailed deer (Odocoileus virginianus Zimmermann) browsing and fire on diversity and number of prairie-forb flowering stems in a remnant tallgrass prairie in northern Illinois. Our study included two plots protected from deer browsing since 1992 and two unprotected plots. All plots were burned twice in late April of 1990 and 1991. Deer densities of 32–50 km−2 (1992–96) declined to 7–9 km−2 in 1998 and 1999 after controlled hunting. Similarity between protected and unprotected plots was initially 82%, declined to 49% during the period of high deer density, and increased to 68% in 2001 with managed hunting. Flowering stems for all forbs were tallied in 1998–2001. Diversity (Shannon index [H′] and effective number of stems [HO]) of flowering stems was higher on protected than on unprotected plots for all study years. Differences in composition and diversity between protected and unprotected plots were associated with interactions between fire and protection from deer browsing as measured by total number of flowering stems, which was significantly higher on protected than on unprotected plots in nonburn years (3.4–3.5-fold) but not in burn years (1.0–1.2-fold). The two leading species on protected plots (ashy sunflower [Helianthus mollis Lam.] and Culver's root [Veronicastrum virginicum (L.) Farw.]) tended to have fewer flowering stems in burn years and always had them in protected plots (54-fold and 70-fold higher in protected plots for the two species, respectively). For the second leading species on unprotected sites (wild quinine [Parthenium integrifolium L.]), the number of flowering stems was significantly higher in burn years (27-fold); however, there was no significant difference in the number of stems between protected and unprotected plots. These results show strong interactions between fire and deer-browsing disturbances in communities recovering from deer overabundance.

Genetic diversity of wild sunflower (Helianthus sp.) accessions with different tolerance to mid-stalk white rot

Random amplified polymorphic DNA (RAPD) markers were used to detect polymorphism among accessions of wild sunflower species H?lianthus maximiliani, Helianthus tuberosus, Helianthus mollis and Helianthus rigidus with different tolerance to mid-stalk white rot and selection of potential markers for different levels of tolerance to this disease. Estimates of genetic variation showed that genetic diversity was equally distributed between Helianthus species and within them. Cluster analysis corresponded to the phylogenetic relations within the genus Helianthus. The results obtained by principal coordinates analysis (PCoA), where the first two principal coordinates accounted for 83.7% of total variation, perfectly coincided with the results of cluster analysis. Contingency coefficient significance test showed that most of the used primers generated bands associated with some level of tolerance or susceptibility to mid- stalk white rot. Furthermore, contingency analysis showed that primer C12 generated bands associated with resistance (100%) to mid-stalk white rot both in H. mollis and in all accessions, while primer X18 generated bands significantly associated with high tolerance (75%) in H. rigidus, H. mollis as well as in all tested accessions. The C15-600 bp locus was found to be significantly associated with high tolerance (75%) in all accessions, and medium tolerance (50%) in H. mollis.

Ontogeny strongly and differentially alters leaf economic and other key traits in three diverse Helianthus species

The leaf economics spectrum (LES) describes large cross-species variation in suites of leaf functional traits ranging from resource-acquisitive to resource-conservative strategies. Such strategies have been integral in explaining plant adaptation to diverse environments, and have been linked to numerous ecosystem processes. The LES has previously been found to be significantly modulated by climate, soil fertility, biogeography, growth form, and life history. One largely unexplored aspect of LES variation, whole-plant ontogeny, is investigated here using multiple populations of three very different species of sunflower: Helianthus annuus, Helianthus mollis, and Helianthus radula. Plants were grown under environmentally controlled conditions and assessed for LES and related traits at four key developmental stages, using recently matured leaves to standardize for leaf age. Nearly every trait exhibited a significant ontogenetic shift in one or more species, with trait patterns differing among populations and species. Photosynthetic rate, leaf nitrogen concentration, and leaf mass per area exhibited surprisingly large changes, spanning over two-thirds of the original cross-species LES variation and shifting from resource-acquisitive to resource-conservative strategies as the plants matured. Other traits being investigated in relation to the LES, such as leaf water content, pH, and vein density, also showed large changes. The finding that ontogenetic variation in LES strategy can be substantial leads to a recommendation of standardization by developmental stage when assessing 'species values' of labile traits for comparative approaches. Additionally, the substantial ontogenetic trait shifts seen within single individuals provide an opportunity to uncover the contribution of gene regulatory changes to variation in LES traits.

Transfer of architectural traits from perennial Helianthus mollis Lam. to sunflower (H. annuus L.) and localisation of introgression

Common sunflower (i.e., Helianthus annuus) is occasionally crossed with other Helianthus species to gain favourable agronomic traits. An interspecific cross between H. annuus and Helianthus mollis was used to examine events that occurred during the five first generations. First generation hybrid plants were verified using GISH, and F1 hybrid (#17) was back-crossed to common sunflower to obtain BC1 (#4) and BC2 (#21). Some BC2 progeny possessed new traits, i.e., compact (Compact plant architecture is due to short inter-node length, short petiole length and short leaf lamina length) architecture without and with corrugated leaves, which were not observed in the parents. These traits were selected for and fixed after the BC2-S3 (#18) to produce a H. mollis introgression line (namely HM374). Although the size of the population was small, we tentatively construct a genetic map using data from the BC2 generation. Two linkage groups were identified carrying H. mollis specific AFLP markers that were associated with compact plant architecture, and one unlinked marker was shown to explain variation for the corrugated leaves. Introgression line HM374 was used to test the inheritance of compact plant architecture in a cross with an elite high oleic line, OL75HO. Microsatellite (SSR) markers were used to genotype F1 and F2 offspring’s. Our data suggested that the line HM374 was still heterozygous for introgression after eight generations. HM374 displays new architecture traits (i.e. compact architecture with or without corrugated leaves) and carries H. mollis fragments anchored on LG1 and LG11 of sunflower public map.

DNA polymorphism of wild sunflower accessions highly susceptible or highly tolerant to white rot on stalk

DNA polymorphism in accessions of Helianthus mollis, Helianthus rigidus and Helianthus tuberosus differing in level of resistance to stem white rot caused by Sclerotinia was evaluated in reactions with two RAPD primers, C04 and C15, selected for their potential linkage with resistance to Sclerotinia. In total, 36 fragments using both primers were generated. All fragments generated by C04 were polymorphic, while 5 fragments out of 11 generated by C15 were monomorphic. Two major clusters were identified on the phenogram generated by UPGMA analysis, one comprising plants of H. mollis 1298, and the other where all other accessions were grouped. In order to check and statistically confirm any significant association of specific fragments either with resistance or susceptibility, contingency coefficient test was done. Out of 36 fragments generated, 26 were significantly associated with resistance/susceptibility. Fragment C04-950 bp was found to be significantly associated to susceptibility, as it was generated only in susceptible accessions, while fragment C04- 1200 bp was found to be associated with the resistance, as it only occurred in H. mollis accessions. The selected markers should be checked and results verified in further studies including higher number of wild sunflower accessions differing in their reaction to stem white rot caused by Sclerotinia. [Projekat Ministarstva nauke Republike Srbije, br. TR 31025]

Photosynthetic and Respiratory Acclimation to Experimental Warming for Four Species in a Tallgrass Prairie Ecosystem

AbstractGlobal temperature has been increased by 0.6 °C over the past century and is predicted to increase by 1.4‐5.8 °C by the end of this century. It is unclear what impacts global warming will have on tallgrass species. In the present study, we examined leaf net photosynthetic rate (Pn) and leaf respiration rate in darkness (Rd) of Aster ericoides (L.) Nesom, Ambrosia psilostachya DC., Helianthus mollis Lam., and Sorghastrum nutans (L.) Nash in response to experimental warming in a tallgrass prairie ecosystem of the Great Plains, USA, in the autumn (fall) of 2000 and through 2001. Warming has been implemented with infrared heaters since 21 November 1999. The Pn increased significantly in spring, decreased in early fall, and did not change in summer and late fall in the four species under warming compared with control. The Rd of the four species increased significantly until mid‐summer and then did not change under warming. Measured temperature‐response curves of Pn showed that warming increased the optimum temperature of Pn (Topt) by 2.32 and 4.59 °C for H. mollis and S. nutans, respectively, in August, whereas there were no changes in May and September, and A. ericoides and A. psilostachya also showed no changes in any of the 3 months. However, Pn at optimum temperature (Popt) showed downregulation in September and no regulation in May and August for all four species. The temperature‐response curves of Rd illustrate that the temperature sensitivity of Rd, Q10, was lower in the warmed plots compared with the control plots, except for A. ericoides in August, whereas there were no changes in May and September for all four species. The results of the present study indicate that photosynthetic and respiratory acclimation varies with species and among seasons, occurring in the mid‐growing season and not in the early and late growing seasons.

The effect of UV light on division capacity of Helianthus mollisL. protoplasts

Cultivated sunflower (Helianthus annuus L.), together with soybean, oil seed rape and peanut is one of the four most important crops for oil production and has a cultivated area that range from Russia, Eastern and Central Europe to Central America. Wild sunflower species served as genetic base for the modern sunflower. Cultivated sunflower was selected from a very narrow genetic base. Enlarging the genetic base will allow it to be better adapted to environmental conditions. Many wild species are used to introduce useful traits, such as disease resistance (Phomopsis stem cancer, Sclerotinia wilt), cytoplasmic male sterility and increased oil content to the cultivated crop by introgression. Sexual hybridisation is limited in most cases to cultivars within a species or at best to a few wild species closely related to a cultivated crop. Species barrier thereby limits the genetic improvement by classic breeding. Somatic hybridisation, or somatic cell fusion technique, leading to the formation of viable cell hybrids is one of the methods used to overcome sexual incompatibility. In order to eliminate the unfavourable wild species traits in the somatic hybrids, a number of back crossings to the cultivated sunflower would be necessary. A method to reduce the backcrossings by reducing the amount of DNA from wild species in the hybrids, is the asymmetric fusion of the protoplasts. This technique is used to introduce fragments of the nuclear genome from the wild species into the complete genome of cultivated ones. A fragmentation of the donor genome can be induced by UV irradiation of the donor protoplasts prior to protoplast fusion. The effect of UV-light treatment was determined on the basis of Helianthus mollis protoplast viability and division capacity. The isolation and purificartion of protoplasts was according to Krasnyanski and Menczel [1] protocol. The suspension of purified protoplasts was placed under a UV lamp during 60 min (wavelength of UV irradiation was 254 nm). Irradiation intensity was 2 Mmol m-2 s-1. Protoplast viability was determined every 5 min, on 100 protoplasts, using FDA, under fluorescent microscope. The protoplasts were cultured in agarose droplets in VKM media. Plating efficiency (the number of cells dividing of total number of cells) was determined at 4 and 8 days in culture. We observed the UV irradiation affects both, viability and division capacity of H. mollis protoplasts. Efficiency of UV-light treatment depends on its intensity and duration, a treatment in our conditions of more than 10 min decreases significantly the viability of the tested cells.

Molecular mapping of the Rf1 gene restoring pollen fertility in PET1-based F1 hybrids in sunflower (Helianthus annuus L.).

Up to now a single cytoplasmic male sterility (CMS) source, PET1, is used worldwide for hybrid breeding in sunflower. Introgression of the restorer gene Rf1, responsible for fertility restoration, into new breeding material requires tightly linked markers to perform an efficient marker-assisted selection. A survey of 520 decamer primers by bulked segregant analyses identified five RAPD markers linked to the restorer gene Rf1. In a F(2) population of 183 individuals one of the RAPD markers, OPK13_454, mapped 0.8 cM from Rf1, followed by OPY10_740 with 2 cM. Bulked segregant analyses using 48 AFLP primer combinations identified 17 polymorphisms, which could be mapped in the same linkage group as Rf1. E33M61_136, and E41M48_113 were mapped 0.3 cM and 1.6 cM from the gene, respectively. Conversion of E41M48_113 into a sequence-specific marker resulted in a monomorphic pattern. However, two of the RAPD markers, OPK13_454 and OPY10_740, were successfully converted into SCAR markers, HRG01 and HRG02, which are now available for marker-assisted selection. To investigate the utility of these SCAR markers in other cross-combinations they were tested in a set of 20 lines. Comparison of the patterns of 11 restorer and nine maintainer lines of PET1 demonstrated that the markers OPK13_454/HRG01 and HRG02 were absent in all maintainer lines but present in all restorer lines, apart from the high oleic line RHA348 and the dwarf line Gio55. In addition, restorer lines developed from the interspecific hybrids Helianthus annuus x Helianthus mollis and H. annuus x Helianthus rigidus gave the same characteristic amplification products.

Occurrence of partial hybrids in wide crosses between sunflower (Helianthus annuus) and perennial species H. mollis and H. orgyalis

Hybridisation between the annual diploid sunflower ( Helianthus annuus)and the perennial diploid species Helianthus mollis and Helianthus orgyalis was obtained by means of a normal crossing procedure or embryo rescue. Hybridisation success was low. All plants examined cytologically appeared to be diploid. However, the phenotypes of these diploids were not intermediate between the parents and, despite great variation, they resembled the female parent-type predominantly. Thirty five percent of plants issued from sunflower pollinated with perennial Helianthus had a phenotype resembling the female sunflower parent. On average, only 5% of the minimum number of expected RAPD and RFLP bands from male parents were recovered in plants produced from mature seeds after pollination of sunflower by H. mollis. More hybrids were found among plants obtained from embryo rescue, with an average of 25% of the male parent bands recovered per plant. Analysis of individual plants indicated the occurrence of various levels of hybridisation. There was a significant positive correlation between the number of phenotype traits related to hybrid status and the number of bands derived from the male parent. A single hybrid plant might possibly represent the product of a 'normal' hybridisation event. The mechanisms behind these unusual events and the consequences for the breeder are discussed.

Partial hybridization in crosses between cultivated sunflower and the perennial Helianthus mollis: effect of in vitro culture compared to natural crosses

Eighty-four plants obtained from the pollination of the annual diploid cultivated sunflower, Helianthus annuus, by the perennial diploid species H. mollis were obtained naturally from mature seeds (62 plants) or following embryo rescue procedures (22 plants) and subsequently studied for phenotype traits and DNA markers. Twenty-two plants were obtained from the reverse cross as a result of natural seed development. The level of hybridization was determined using random amplified polymorphic DNA and restriction fragment length polymorphism markers. All of the resulting plants were found to be diploid 2n=34. Reciprocal crosses led to different progenies, with phenotypes that were predominantly similar to that of the female sunflower or the H. mollis type. The embryo rescue procedure enhanced the level of hybridization, whereas natural seed development led to fewer hybrids. Molecular markers unique to the female or the male parent indicated mechanisms leading to partial hybridization.

Genetic Variability as Identified by AP‐PCR and Reaction to Mid‐Stem Infection of Sclerotinia sclerotiorum among Interspecific Sunflower (Helianthus annuus L.) Hybrid Progenies

Various diseases limit productivity in the majority of sunflower (Helianthus annuus L.) growing areas. Sunflower cultivars lack acceptable levels of resistance to Sclerotinia sclerotiorum (Lib.) de Bary, which is a major pathogen in sunflower production. Several wild Helianthus species are potential sources of genes for disease resistance and can be used in interspecific crosses to increase the genetic variability of cultivated sunflower. Progenies of interspecific hybrids between cultivated sunflower lines and Helianthus mollis Lam., H. decapetalus L., H. maximiliani Schrader, H. giganteus L., H. tuberosus L., and H. pauciflorus Nutt were tested for their mid‐stem Sclerotinia reaction by an artificial infection method. Compared with the susceptible commercial hybrid check cv. Frankasol, interspecific hybrid progenies were selected that showed reduced Sclerotinia infection. It could be demonstrated by results of AP‐PCR fingerprinting that interspecific hybrids can be a valuable tool for broadening genetic variability in sunflower. In total, 20 AP‐PCR primers were used for the characterization of interspecific hybrid progenies. It was possible to discriminate between the H. annuus parents and their progenies, where an increased genetic variability resulting from the interspecific hybridizations was detectable. Results of an UPGMA cluster analysis showed that interspecific hybrid progenies which originate in the same cross combination share a common cluster. These lines exhibited a large genetic distance from the parental sunflower inbred lines and form their own distinct genetic pool.

Anther Culture Regeneration from Helianthus Mollis (M-020) and its Hybrid Combinations

ABSTRACTAnthers from the Helianthas mollis (M-020) species and from the hybrid combination H.mollis (M-020) x H.anmms and H.anmtus x H.mollis (M-020) were isolated. Different variants of nutrient media were tested. The most suitable medium for plant regeneration proved to be the B5 medium without hormones and with reduced sucrose content. Regeneration was obtained from the H.mollis (M-020) as well as from the hybrid combination H.mollis (M-020) x H.annuus. Only well formed embryos were obtained from the reciprocal crosses. Investigation on the ploidity level of the regenerants are still in progress.

Meiosis and pollen grain viability in Helianthus mollis, Helianthus salicifolius, Helianthus maximiliani and their F1 hybrids with cultivated sunflower

Three diploid perennial sunflower species are useful for variety improvement: Helianthus mollis, because of sessile leaves, H. salicifolius, because of a high oil concentration, and H. maximiliani, a potential source of resistance to Sclerotinia sclerotiorum. The crossability of these species to cultivated sunflower was examined.

Terpenes of Wild Sunflowers (Helianthus): An Effective Mechanism Against Seed Predation by Larvae of the Sunflower Moth, Homoeosoma electellum (Lepidoptera: Pyralidae)

Sunflower moth, Homoeosoma electellum (Hulst), is a major pest of cultivated sunflower, Helianthus annuus L., in North America. Thirty perennial and 11 annual species of Helianthus and several cultivars of sunflower were evaluated for resistance to H. electellum larvae. Larvae feeding on sunflower inflorescences in laboratory and greenhouse bioassays performed significantly poorer on 14 Helianthus species than on the cultivar hybrid ‘894’. In in vitro bioassays, nonpolar extracts from H. annuus, Helianthus argophyllus Torrey & Gray, Helianthus ciliaris DC, and Helianthus petiolaris ssp. petiolaris Nuttall caused significant lengthening of larval stadia and retarded larval growth. Larvae feeding on purified sesquiterpene lactones and diterpenes from H. argophyllus, H. ciliaris, Helianthus angustifolius L., and Helianthus mollis Lambert in a wheat-germ diet at 0.1–1.0% concentration experienced high mortality, retarded growth, and an extended developmental period. The sesquiterpene lactone 8 β-sarracinoyloxycumambranolide isolated from glandular trichomes on anthers of Helianthus maximiliani Schrader was toxic to young larvae in bioassays. Two mechanisms giving Helianthus resistance to seed injury by larvae of H. electellum are terpenes in the florets and phytomelanin in the pericarp of seeds.