Volume 38, Issue 62 -

Sunflower broomrape Orobanche cumana W allr . is a rapidly growing threat to the oil crop production in many countries. Fast adaptation to new environments and increasing host resistance suggests that phenotypically distinctive populations of the weed may have evolved. The classification of the species and the differentiation of such populations on the base of seed micromorphological characters were attempted. Morphometric measurements allowed the distinction of O. cumana from several other Orobanche and Phelipanche species. An irregularly thickened cell wall of the anticlinal testa cells differentiated O. cumana and O. cernua from O. caryophyllacea, O. crenata , O. minor , P. aegyptiaca , P. arenaria and P. ramosa . However, populations of sunflower broomrape from five European countries and China could not be separated from each other on the base of micromorphological seed characters. In contrast, length to width measurements indicated that the Asian samples had a slightly different seed shape which was less elongated than the European samples. However, this seemingly geographic effect may as well be a consequence of sampling which comprised a higher rate of the so-called modern races E-H in the European samples.

Due to their forms and colors, parasitic plants are most often considered to be botanical curiosities. However, in some cases, these are proved to be also deadly pests with the capacity to exploit other plants. Among the obligate root parasitic weeds, the holoparasites that are devoid of chlorophyll and thus unable to carry out photosynthesis totally rely on their hosts for their water, mineral, and carbohydrate supplies. Members of the genus Orobanche and Phelipanche , belonging to the Orobanchaceae family (the broomrape family), are thus the final result of this evolutionary transition from autotrophism to heterotrophism. The underlying process of this trophic exploitation, governed by a fine-tuned molecular dialogue between both partners, is an extraordinary example of adaptive plant biology operated by these parasitic organisms in the course of evolution. This transition is associated with remarkable morphological and physiological adaptations, such as the requirement for the seeds to germinate to perceive molecules produced by host roots, the development of a novel organ, the haustorium , which invades host tissues and establishes a physiological continuum between the parasite and the host, the establishment of a sink strength required for translocation of host resources, the loss of photosynthesis, and a reduced leaf and root architecture.

Determining the mode of action of allelochemicals is one of the challenging aspects in the allelopathic studies. In this research, the methanolic extracts of wild poinsettia ( Euphorbia heterophylla Linn.) at different concentrations (0, as untreated control, 8%, 12% and 16%) were tested for genotoxic and inhibitor activity on morphological, biochemical and molecular traits of sunflower ( Helianthus annuus L.). Seedling emergence was reduced with wild poinsettia leaf extracts in sunflower. Leaf extracts of wild poinsettia decreased chlorophyll a and b levels and consequently the soluble sugar content was proportional to the increase in the concentrations of the leaf leachates. Some changes occurred in random amplification of polymorphic DNA (RAPD) profiles, profiles of protein bands and total soluble protein of germinated treated seed. These included variation in band intensity, loss of bands and appearance of new bands compared with control. Increased concentration of extracts caused increasing the total soluble protein content, decreasing genome template stability (GTS) value and increasing polymorphism values, the results indicated that they were dose dependent. For instance, the highest and lowest amounts of GTS were observed in 8% and 16%, respectively. In a dendrogram constructed based on genetic similarity coefficients, the treatments were grouped into two main clusters: (a) 8%, 12% and 16% dose clustered together and (b) untreated control grouped alone. Also, we concluded that the basis of interaction between plants, like allelopathy, may be related with genotoxic effects.

To follow heat shock proteins (HSPs) expression in sunflower seeds as portion of total seed storage proteins (SSPs), we kept all agronomic factors constant except temperature. In this research, a drought-tolerant sunflower hybrid was planted under normal and drought stress conditions in order to investigate the effect of temperature on protein synthesis and accumulation during achene filling phase. The analyses of proteins were carried out by two-dimensional electrophoresis (2-DE), after total protein extraction from achene 25 days after pollination. In total, at least 542 protein spots were detected in seeds at normal growth condition versus 551 protein spots in seeds of stress condition. The presence of a polypeptide bond of 17.7 kDa as a small heat shock protein (SHSP) was only observed in seed grown in drought stress and the accuracy of identification was confirmed by micro-lab-on-chip capillary electrophoresis.

High temperature enhances the oleic acid content in the oil of normal cultivars but conflicting results are reported on temperature effects on oleic acid content in HO cultivars: either no effect or an increase in oleic acid content with temperature. To investigate the effects of temperature on HO genotypes under natural field conditions, a three-year field trial was conducted using two sowing dates and three HO genotypes (two inbred lines and one hybrid). To compare our results with previous works, growing degree-days (GDD) were computed (base temperature=6°C). GDD accumulated during the “flowering – 25 days after flowering” period influenced fatty acid composition of seed. Oleic and linoleic acid contents were affected by accumulated GDD in two HO genotypes (one inbred line and the hybrid). There was an increase of about 3% in oleic acid content as response to more high GDD accumulated. Their content was not modified by GDD in the other inbred line. There was a genotype×environment interaction that we suppose depending on modifier genes. These genetic factors affected oleic acid content. This indicated the importance of breeding targeted to select hybrids with a stable oleic acid content and higher than 90%. Saturated fatty acids (palmitic and stearic) were also influenced by temperature, and there was genetic variability among genotypes.

The first document that attests the cultivation of sunflower on the territory of the Republic of Moldova dates back to 1845. The first evidence of oil production from sunflower seeds has been identified in 1867. Since then, the area cultivated with sunflower has expanded exponentially. Sunflower has now become the third most produced crop, after corn and wheat. In the Republic of Moldova, sunflower research activities have been focused on genetics, breeding and improvement of crop cultivation technologies, with a special emphasis on resistance to disease and pests including broomrape, which can considerably diminish crop productivity. Significant efforts have been invested to identify solutions for fighting parasites, such as the investigation of morpho-physiological, biochemical and genetic aspects of the host–parasite interaction; the development of chemical and agro-technical methods to fight parasites; the evaluation of genetic resistance in artificial and natural conditions; the development of hybrids resistant to a number of Orobanche varieties; and the monitoring of broomrape impact on the production indices. The current paper examines the scientific information available, providing a comprehensive view on the management, breeding, resistance and economic impact of sunflower broomrape in the Republic of Moldova. The review aims to provide a perspective for future research strategies to further develop our understanding of the parasite–host interaction.

Hybrid Rada was developed with simple cross of Bulgarian line cms2607 and mutant line 12002 R. Mutant line was developed after treatment of immature sunflower ( Helianthus annuus L.) zygotic embryos of fertility restorer line R 2574 with gamma irradiation at dose of 8 Gy for 1 min. Hybrid Rada was tested for three years in testing plots of Dobroudja Agricultural Institute – General Toshevo and for two years at the seven locations of State Variety Testing Commission. The ANOVA procedure proves that the parents (2607 A and 12002 R) and the received hybrid Rada are with different genetic potential in the studied indices. In our study, all six characters recorded positive and significant heterosis in the direction of both relative to parental average (h1) and relative to better parent (h2). The correlations of the hybrid Rada with the mean values of the parental lines (h1) and with the mean value of the parent with higher indices (h2) were statistically significant. In h1, the variation was from 1.52% to 17.92%; in h2, the variation was within 1.49–12.81%. The highest positive heterotic effect (h1 = 17.92%) in the hybrid Rada was for trait seed yield per head relative to parental average h1. The model of inheritance of studied indices is additive dominant with partial or full dominance in relation to parent with the higher value. This was markedly expressed for indices seed yield per head.

Nine new cms analogues on the base of diversified cms sources were developed and evaluated for morphological, agronomic, physiological and biochemical traits, including the field resistance to the prevalent diseases of sunflower under Punjab conditions. As a result of this study, the most prospective cms analogues were designated for future use in hybrid breeding programme. The results revealed that selection for tall plants with large head size and high chlorophyll content may be associated with high grain yield as well as oil content and high oleic acid content in sunflower. Leaf dry weight, biological yield, harvest index, specific leaf weight and relative leaf water content had direct positive effect on grain yield. The harvest index, specific leaf weight/plant, leaf area index and leaf area had indirect effects (through leaf dry weight) on grain yield. These traits are advocated as selection criteria for grain yield improvement in sunflower.

The sunflower breeding carried out in Argentina constitutes a valuable contribution to the spreading of the crop both locally and internationally. Exchange among breeders at international level makes it possible to achieve objectives that would be restricted if only local germplasm were available (lack of variability). The National Institute of Agricultural Technology (INTA) has had a sunflower genetic breeding program at Pergamino Experimental Station (EEA) since 1939 and another program at Manfredi Experimental Station (EEA) since 1950 with the overall goal of contributing to increase the rate of genetic progress of the crop. At first the program development open pollination varieties using the populations which were introduced both by immigrants adapted to local conditions and by intercrossing them. With the development of cytoplasmic androsterility in the 1970s, the programs focused on producing inbred lines to develop hybrids. The varieties and lines were made available to other breeders in a scheme of exchange that allowed INTA, other national breeders and breeders from other countries to obtain new materials. In this way it became clear the great wealth of INTA germplasm for resistance to major crop diseases such as Verticillium wilt, rust and downy mildew. Other important traits improved were the increase of seed weight and tolerance to bird damage by adding striated seeds and decumbent heads. Also by its origin INTA germplasm enabled the increase of oil content, improvements in the quality and specialties (high oleic acid, confectionery) and tolerance to herbicides (imidazolinone), while maintaining the performance and health of the materials. This paper describes the origins and characteristics of INTA lines and also their use in other breeding programs for the creation of new cultivars.

The anatomy of involucral bracts (IB) of the capitulum was studied in two sunflower domesticated primitive genotypes ( Helianthus annuus L.), Havasupai and Hopi, HA89B line and DKOP3845 hybrid. Stomata and trichomes were counted on the adaxial and abaxial epidermis. In all cases the IB showed an one-layered adaxial and abaxial epidermis, secretory ducts and parenchymatic cells with abundant chloroplast. The vascular system was similar to that of the foliage leaves; however, their bundles were smaller, with an abaxial surface with higher abundance of glandular and non-glandular trichomes and with the presence of stomatas. IB of Havasupai and Hopi showed higher number of adaxial hypodermic strata than those of HA89B and DKOP3845 (4 vs. 1) and one mesophyllum with inverted polarity with respect to a foliage leaf: the presence of a spongy parenchyma on the adaxial side was observed with a rudimentary palisade parenchyma on the abaxial side. Stomatal density of the IB was significantly higher in Hopi and Havasupai than in HA89B and DKOP3845, with values ranging from 132 to 156 vs. 73 to 110 stomata/mm 2 respectively. It is concluded that from the functional point of view, sunflower breeding produced undesired changes in the IB anatomy.