Allelopathic Effect of Aqueous Extracts of Stinkwort (Dittrichia graveolens L.) on Germination and Growth of Some Weed Species

The experiment was implemented by CRD design with three replications and lasted for 40 days, from 5 October until 15 November 2020. Four extract concentrations of D. graveolens 0, 2, 6, and 10% were used. The concentration of 0% was considered as control. The allelopathic effect has been studied on five weed species; Amaranthus retroflexus L., Portulaca oleracea L., Lolium multiflorum Lam., Sorghum halepense L., and Cuscuta campestris Yunck. The research also aimed to determine the effect of Stinkwort extract on the growth of tomato seedlings. All concentrations affected seed germination for all studied weeds. The concentration of 10% was more influential in growth-related indicators compared to other concentrations. The seeds of L. multiflorum and rhizomes of S. halepense were more tolerant to D. graveolens allelochemicals in germination rate than A. retroflexus, P. oleracea, and C. campestris. All concentrations led to a reduction in the weed heights and the wet and dry weights compared with the controls. The effect of the extract with various concentrations was catalytic for the growth of tomato seedlings, as the average height of tomato seedlings was in direct proportion to the concentration.

Allelopathic Effect of Aqueous Extracts of Stinkwort (Dittrichia graveolens L.) on Germination and Growth of Some Weed Species

The experiment was implemented by CRD design with three replications and lasted for 40 days, from 5 October until 15 November 2020. Four extract concentrations of D. graveolens 0, 2, 6, and 10% were used. The concentration of 0% was considered as control. The allelopathic effect has been studied on five weed species; Amaranthus retroflexus L., Portulaca oleracea L., Lolium multiflorum Lam., Sorghum halepense L., and Cuscuta campestris Yunck. The research also aimed to determine the effect of Stinkwort extract on the growth of tomato seedlings. All concentrations affected seed germination for all studied weeds. The concentration of 10% was more influential in growth-related indicators compared to other concentrations. The seeds of L. multiflorum and rhizomes of S. halepense were more tolerant to D. graveolens allelochemicals in germination rate than A. retroflexus, P. oleracea, and C. campestris. All concentrations led to a reduction in the weed heights and the wet and dry weights compared with the controls. The effect of the extract with various concentrations was catalytic for the growth of tomato seedlings, as the average height of tomato seedlings was in direct proportion to the concentration.

Nowe stanowiska roślin naczyniowych Polski, 2

Streszczenie W pracy przedstawiono nowe stanowiska 12 rzadkich (lub regionalnie rzadkich) roślin naczyniowych w Polsce, tj. Cochlearia danica , Colchicum autumnale , Cuscuta campestris , Lythrum hyssopifolia , Ostericum palustre , Pedicularis sylvatica , Plantago coronopus , Ranunculus arvensis , Rosa gallica , Sesleria uliginosa , Succisella inflexa oraz Veronica prostrata .

IMPACT OF THE INVASIVE CUSCUTA CAMPESTRIS ON VEGETATIVE COVER AND PLANT BIODIVERSITY IN HOMA- BAY COUNTY

Purpose: This research paper focused on the impact of Cuscuta campestris on vegetative cover and plant biodiversity in Homa-Bay County. The specific objective was to investigate the impact on plant growth and development with indicator as photosynthetic capacity of preferred host plants and chlorophyll content and leaf weight as the parameters. Methodology: The study was conducted in hot-spot areas of invasion, Rachuonyo North, Homa Bay town and Suba North using Completely Randomized Experimental Block Design. The data was collected through field observation and laboratory analysis. The study used descriptive and correlation data analysis procedures to show the impact on photosynthetic capacity, ANOVA to determine statistical significant difference among the obtained results for each parameter of the infected and uninfected samples. Variance analysis were conducted using SPSS 20 (IBM Corp. Armonk, NY, USA) and differences between means tested by ANOVA. Values of P ≤ 0.05 were considered significantly different. Findings: The results showed that the invasion was more intense in Theveta peruvinia and Euphorbia tirucalli species. Mean leaf amounts of chlorophyll were observed to decline with chlorophyll a from 3.97 to 1.59 mg/g and chlorophyll b from 2.65 to 1.18 mg/g and total chlorophyll value from 6.62 to 2.76 mg/g on infection resulting to reduced photosynthetic efficiency and low organic material formation. Leaf wet and dry weight significantly decreased in both infected varieties. The mean wet weight of 17.61g in infected was significantly different, F (1, 4) = 235.74, p< .05, from the mean wet weight of 24.23g in the uninfected Yellow Oleander while the mean dry weight of 5.55g in infected was significantly different, F (1, 4) = 159.72, p< .05, from mean dry weight of 7.87g in uninfected Yellow Oleander. Similarly, significant difference, F (1, 4) = 714.64, p< .05, was observed in Calliandra calothyrsus variety. These demonstrated how C. campestris is detrimental causing ecological impacts with direct effects on plant biodiversity by reducing growth and development of infected host plant and even leading to death. Unique Contributions to Theory, Practice and Policy: The paper recommends intense sensitization of the community on the impacts of dodder from the findings for an enhanced understanding and need for management and control. The findings to be disseminated through workshops involving farmers, NGOs and community based organisations, academic conferences and publications to help create awareness on the impacts and mobilize the entire public on management and possible total eradication. Further research to investigate on nutrients of attraction in the preferred host plants with an aim of permanent solution for total eradication in order to restore the vegetative cover and plant biodiversity.

The Effect of a Host on the Primary Metabolic Profiling of Cuscuta Campestris’ Main Organs, Haustoria, Stem and Flower

Cuscuta campestris (dodder) is a stem holoparasitic plant without leaves or roots that parasitizes various types of host plants and causes damage to certain crops worldwide. This study aimed at gaining more knowledge about the effect of the hosts on the parasite’s levels of primary metabolites. To this end, metabolic profiling analyses were performed on the parasite’s three main organs, haustoria, stem and flowers, which developed on three hosts, Heliotropium hirsutissimum, Polygonum equisetiforme and Amaranthus viridis. The results showed significant differences in the metabolic profiles of C. campestris that developed on the different hosts, suggesting that the parasites rely highly on the host’s metabolites. However, changes in the metabolites’ contents between the organs that developed on the same host suggest that the parasite can also self-regulate its metabolites. Flowers, for example, have significantly higher levels of most of the amino acids and sugar acids, while haustoria and stem have higher levels of several sugars and polyols. Determination of total soluble proteins and phenolic compounds showed that the same pattern is detected in the organs unrelated to the hosts. This study contributes to our knowledge about the metabolic behavior of this parasite.

The features of xylem tracheary elements in some herbaceous members of the family Convolvulaceae Horan.

Numerous narrow xylem tracheary elements (tracheids and vessels) are present in liana stems, along with a few wide vessels that perform the main water-conducting function. This trait, known as “vessel dimorphism”, has been identified in studies on water-conducting tissue in autotrophic plants, including a large number of perennial climbing plants and a number of annual vines. Information is lacking on the presence of vessel dimorphism in parasitic plants of the lianescent habit. In this study, we performed a structural analysis of stems in the autotrophic herbaceous vines of Convolvulus arvensis L. and Calystegia sepium (L.) R. Br., as well as in the parasitic vines of Cuscuta monogyna Vahl, Cuscuta planiflora Ten., Cuscuta approximata Bab., and Cuscuta campestris Yunck., of the family of Convolvulaceae Horan. The xylem of C. arvensis and C. sepium contains a few wide conductive elements and many narrow ones. This feature is typical of autotrophic climbing plants. Only narrow tracheary elements are present in the xylem of the parasitic vines of the genus of Cuscuta L. (dodders). The total number of the tracheary elements is an order of magnitude less in the dodders than it is in the autotrophic vines. It is possible that the autotrophic ancestor of dodders lost the characteristic feature of the xylem of climbing plants, known as vessel dimorphism, during its transition to the parasitic lifestyle.

Parasitism-evoked horizontal gene transfer between plants as a novel trigger for specialized metabolism evolution

Recent genomic studies of parasitic plants have revealed that there are numerous footprints indicative of horizontal gene transfer (HGT) to the parasites from their host plants. However, the molecular mechanisms and biological impacts of this phenomenon have remained largely unknown. Here, we made the striking observation that two parasitic dodders, Cuscuta campestris and C. australis, have functional homologues of Si_CYP81Q1, which encodes piperitol/sesamin synthase (PSS) in the phylogenetically remote plant Sesamum indicum (sesame). The apparent lack of sequence similarity between the regions flanking PSS in Sesamum and Cuscuta spp. suggests the occurrence of HGT tightly associated with the PSS gene. Upon parasitism, C. campestris induced expression of the host Si_CYP81Q1 at the parasitic interface and mature and intron-retained Si_CYP81Q1 mRNA was transferred to C. campestris, suggesting that CYP81Q1 was translocated via RNA-mediated HGT. Thus, parasitism-evoked HGT might have had an unexpected role in the metabolic evolution of plants.