Volume 39, Issue 65 -

Genetic resources are the biological basis of global food security. Collection and preservation of wild relatives of important crop species such as sunflower provide the basic foundation to improve and sustain the crop. Acquisition through exploration is the initial step in the germplasm conservation process. There are 53 species of wild Helianthus (39 perennial and 14 annual) native to North America. An exploration covering 3,700 km to the desert southwest United States in mid-June of 2015 led to the collection of five populations of H. deserticola (desert sunflower) and 10 H. anomalus (sand sunflower) accessions. All populations were collected throughout the broad distributional range of the species. Based on sand sunflower’s occurrence in desert sand dune habitats of Utah and Arizona, it frequently has been recognized as drought tolerant, with the largest achenes of any wild species and relatively high oil concentration potential, and thus is a candidate for improving cultivated sunflower. Desert sunflower is a xerophytic annual species found in sandy soils underlain with clay soils on the floor of the Great Basin Desert in small populations in western Nevada, west central Utah, and along the border of Utah and Arizona. Population size, habitat, soil type, seed set, the presence of diseases and insects, and other wild sunflower species located near the collection sites were recorded for each population. This germplasm will be important now and in the future as a genetic resource for the global sunflower crop and at the same time conserve it for future generations.

Secondary metabolites serve multiple functions in plants, and play a key role in many ecological processes. Accordingly, the quantification of such compounds is central to addressing many questions in plant science. Alongside precision analytical methods like gas and liquid chromatography-mass spectrometry, there exists a substantial niche for inexpensive and rapid spectrophotometric approaches if their usefulness in a system can be demonstrated. This study seeks to examine the utility of two commonly used colorimetric methods – the Folin-Ciocalteu assay and the aluminum complexation assay – for quantifying variation in leaf phenolic and flavonoid content among members of the genus Helianthus , the sunflowers. Among species known a priori to vary substantially in both the diversity and relative concentrations of secondary metabolites, both assays detect substantial variation among species. Moreover, total phenolic content as assessed by the Folin-Ciocalteu assay correlates positively with concentrations of multiple individual phenolic compounds as quantified by high performance liquid chromatography-mass spectrometry, indicating that the Folin-Ciocalteu describes variation in sunflower phenolic content. Additionally, the diversity of flavonoids known from Helianthus include a number of those known to be sensitive to the aluminum complexation assay, indicating that this assay may also be a useful descriptor of relative variation in sunflower flavonoid content. In total, both the Folin-Ciocalteu and aluminum complexation assays appear to capture useful, if coarse, variation in secondary metabolites among Helianthus species, and seem useful as rapid low-cost methods for exploratory research, preliminary analyses, and potentially useful for high-throughput phenotyping within wild or cultivated sunflower with proper calibration.

Sunflower line with resistance for downy mildew (Ha-26R) and susceptible line (Ha-26S) were inoculated with the suspension of Plasmopara halstedii zoosporangia, race 730, in the phase of first pair of leaves. The expression of defense related genes was investigated in the time period of 2 to 96 h after treatment. Several categories of defense-related genes: signalization (EDS1 and EDR1); H 2 O 2 producing (Hacaox and Haoxox); antioxidative response (SODc and SODp), pathogenesis related (chi, PAL, PR5) were examined. Most examined defense related genes were constitutive with higher expression in resistant line. However, in response to secondary downy mildew infection six genes were upregulated. Upregulation of HaEDS1 signaling gene 2 h after infection indicates that SA mediated response is activated. Pathogenesis related genes: chitinase and PR5, were also upregulated in the earliest time point. Other defense related genes: SODp, Caox and OxOx were sequentially upregulated from 4 to 48 h after infection in resistant line. Our results indicate that the early response of defense related genes to secondary downy mildew infection, resembles to hypersensitive-like reaction and is connected with resistance conferred by Pl6 gene. According to our results resistance to secondary infection is characterized with earlier upregulation of PR5 in comparison to primary infection.

The genetic stocks of SURES-1 and SURES-2 showed complete tolerance to tribenuron-methyl. No resistance were obtained after observation on 200,000 plants of four VNIIMK breeding lines grown on an experimental field with total area of 5 ha treated with Express at 1x rate. Potential frequency of a dominant gene for tolerance to tribenuron-methyl was estimated less than 5×10 −6 . Moreover screening both of 700 plants of 39 inbred lines of the genetic collection and 800 plants of M 2 four breeding lines did not reveal any resistance. Tolerance to tribenuron-methyl in F 1 and F 2 in the crosses of SURES-1 and SURES-2 with VNIIMK breeding lines was controlled by one dominant gene. All recessive homozygous hybrid plants of sur sur genotype in the cross were dead with phytotoxicity index of 9 after Express treatment at any rate of tribenuron-methyl from 0.5x to 4x. Heterozygous hybrid plants of Sur sur genotype showed no injury symptoms at 0.5x rate and increasing level of phytotoxicity index of 4, 6 and 7 for 1x, 2x and 4x rates correspondingly. Dominant homozygous hybrid plants of Sur Sur genotype possessed no injury symptoms from 0.5x to 2x rates whereas the phytotoxicity index of 4 was observed at the 4x rate. Consequently there was no difference between dominant homozygote Sur Sur and heterozygote Sur sur with phytotoxicity index of 0 at 0.5x rate. Allelic interaction in a heterozygote Sur sur can vary from complete to partial dominance in accordance with increasing rate of tribenuron-methyl treatment estimating with the phenotypic scale of phytotoxicity index.

Broomrape (Orobanche cumana Wallr.) is an important parasite in sunflower crop in Europe, some Asian countries and Australia. The parasite has spread in sunflower crop from south Russia and Ukraine. In Romania this was identified for the first time in 1940–1941 year, the most infested area being in central and south Moldavia, south Dobrogea and eastern Baragan. The negative impact of broomrape on sunflower could be found on the cultivated as well as on wild sunflower. For broomrape controlling there have been created resistant sunflower hybrids to different races of the parasite. This paper presents the results obtained by testing sunflower differential set for broomrape races A to F as well as some commercial hybrids for races more virulent than F. Using this differential set and hybrids it has been done testing in different locations from Braila county, in 2014 and 2015 years. We found that in Braila area there are present all races of the parasite which have been identified up to now in sunflower crop in Romania, having important differences between different locations. So, in some locations there is present, as the most virulent, race E, in other locations race F, in some other locations having the most virulent races, more than F. In some locations the parasite is very aggressive, having around one hundred broomrapes per one sunflower plant. We have identified the new races of the parasite in areas were one year before these have not been present.

Based on the biological characteristics of sunflower, Krasnodar region is the most favorable area for high and stable yields of this crop in the Russian Federation. However, there is a manifestation of the drought in the summer time that adversely affects the productivity and quality of sunflower seeds. Increased resistance to adverse weather conditions is possible only on the basis of deep studying of the physiological features of formation of productivity and quality of seeds, which is a very urgent task The effect of plant growth regulator furolan on growth, productivity and the formation of physical and chemical indicators of quality of sunflower seeds of the P-453 varieties, the SEC and the RMS selection by VNIIMK were investigated. The treatment of vegetative plants by furolan has activated the growth and biomass accumulation in the stems, improved the photosynthetic activity of plants, leaf area increased, thereby increasing their life expectancy and productivity of photosynthesis. Increased plants productivity reduced their empty grain, increasing the geometric dimensions of the seeds and sunflower kernels, reduced seed husk content, oil content and increased oleic acid content in the oil.

Based on long-term work on induced mutations using dimethyl sulfate (DMS) at medium doses (concentrations) a large number of mutagenic lines was obtained. The source cultivar for obtaining the mutants was VNIIMK 8931. The mutations were obtained by changing the growth period, plant height, stem form, changes of the head (size, form, and shape), changes of the leaves (color, size, form, serratedness, petiole length), and changes of the size, shape, color and levels of oil and protein and their quality. The most important mutations presented in this paper pertain to resistance to low temperatures (up to –30 °C) in what can be termed winter sunflower (M-2002-Morzh and M-1701-Ice King). Of great value is also the mutant M-1880-Udochka (aphylla leafless) with its small leaves and short petioles, which enables the increase in plant population of up to 500,000 plants/ha.