Genetic Variability of Acetolactate Synthase (ALS) Sequence in Centaurea cyanus Plants Resistant and Susceptible to Tribenuron-Methyl

Centaurea cyanus, belonging to the Asteraceae family, is an arable weed species encountered mainly in fields with cereals, sugar beet, and maize. The high genetic variability of C. cyanus has been recently reported; however, little is known about its sequence variability in the context of its herbicide resistance. C. cyanus resistance was found mainly against acetolactate synthase (ALS) inhibitors, but no ALS sequence information concerning the herbicide resistance mechanism has been published yet. The aim of this study was to determine the ALS sequences for biotypes susceptible and resistant to tribenuron-methyl in order to identify mutations that may be associated with the resistance emergence. DNA isolation from susceptible and resistant plants was followed by PCR amplification and ALS sequencing. As a result, different lengths of DNA products were obtained. Moreover, both nucleotide and amino acid sequence analysis revealed high sequence variability within one plant as well as between plants from the same biotype. In a few resistant plants, four changes in the amino acid sequence were identified in comparison to those in the susceptible ones. However, these preliminary studies require further investigation toward confirming the significance of these mutations in herbicide resistance development. This study provides preliminary information contributing to the research on the C. cyanus target-site resistance mechanism.

Plant-based nanoparticles prepared from protein containing tribenuron-methyl: fabrication, characterization, and application

Background Tribenuron-methyl is a registered herbicide for broad-leaf weed control in wheat, however, low solubility in water and reacting with hard water's ions could substantially decrease its efficacy. The present work aimed to enhance the dispersing and bioactivity of this herbicide by developing nanoparticles using zein as a promising nano-delivery system and to assess the effects of nanoparticles on the efficacy of tribenuron-methyl in the suppression of Convolvulus arvensis as a problematic weed in wheat fields. Results Based on SEM analyses nanoparticles sizes were 80–120 nm. DLS results showed an average size of 170 nm for tribenuron-methyl zein-based nanoparticles (TMZNP-5). The entrapment efficiency (EE%) of tribenuron-methyl inside the zein nanoparticles was ca. 81% ± 3. Five-week after application of tribenuron-methyl nanoparticles on C. arvensis, it was able to reduce the dry weight (53%), acetolactate synthase (ALS) enzyme activity (82%), and plant height (77%) of C. arvensis as compared with untreated plants. Additionally, tribenuron-methyl used in nanoparticles at the half rate of the recommended dose had the same efficacy as commercial tribenuron-methyl. Conclusion Based on these results, zein nanoparticles can be potentially utilized as nanocarriers for enhancing the solubility of tribenuron-methyl to further enhance its bioavailability and performance on sensitive weeds. Graphic abstract

Efficiency of selection–biotechnological system of selection for creation of breeding source material of sunflower resistant to herbicides and broomrape

The sunflower is a strategically important oil crop. Every year the area under this crop grows, and the rapid returning of sunflowers back to the fields provokes the formation of new more aggressive races of broomrape (Orobanche cumana Wallr.). Broomrape is a parasite that interferes with the normal development of sunflower and can lead to significant crop losses. For creating a sunflower hybrid (F1) it is needed to cross the parental components, which have a complex of important traits, among which there is a resistance to the herbicides and a broomrape. Considering that the creation of each of the components of the hybrid involves many years of painstaking work in the breeding process, modern approaches and methods are used to accelerate the creation of a new source material. Thus, using the technology of cultivating immature embryos in vitro culture, it is possible to reduce the time to create lines resistant to herbicides, for example. And during selection for resistance to pathogenic organisms, testing is most often used against an artificial infectious background, both in the field and in laboratory conditions, in order to differentiate the material on this basis. The aim of this work was to establish the effectiveness system when creating an initial breeding material resistant to herbicides and broomrape. As a result of testing the lines on an artificial infectious background, was identified plants which have high resistance to the G-race broomrape and were isolated from hybrid combinations resistant to tribenuron-methyl and imidazolinones. Thus, among the analyzed plants which are resistant to tribenuron‐methyl, four lines were isolated, which are highly resistant to the G-race broomrape from a hybrid combinations BH0118/SURES–2 (101/1, 101/4, 101/6, 101/7), and BH0318/SURES–2 (101/21, 101/24, 101/28, 101/30), and five lines (101/11, 101/12, 101/16, 101/17, 101/18) from a hybrid combination BH0218/SURES–2. Among imidazolinone-resistant sunflower lines – line 3 was isolated as highly resistant to the G-race broomrape.

Genetic Variability of Acetolactate Synthase (ALS) Sequence in Centaurea Cyanus Plants Resistant and Susceptible to Tribenuron-methyl

Centaurea cyanus, belonging to the Asteraceae family, is an arable weed species being encountered mainly in the fields with cereals, sugar beet, and corn. C. cyanus high genetic variability has recently been reported, however, little is known about sequence variability in the context of herbicide resistance. C. cyanus resistance was found mainly against acetolactate inhibitors (ALS) inhibitors, but no ALS sequence information concerning herbicide resistance mechanism has been published yet. Therefore, the aim of this study was to determine ALS sequences for biotypes susceptible and resistant to tribenuron-methyl in order to identify possible mutations conferring the resistance. DNA isolation from susceptible and resistant plants was followed by PCR amplification and sequencing of ALS sequence. As a result different lengths of DNA products were obtained. Moreover, both nucleotide and amino acid sequence analysis revealed high sequence variability within one plant as well as between plants from the same biotype. In a few resistant plants, six changes in amino acid sequence were identified in comparison to susceptible ones. However, these preliminary studies require further investigation toward confirming the significance of these mutations in herbicide resistance development. This study provides the first attempt in the research on C. cyanus target-site resistance mechanism.

Characterization of resistance and fitness cost of Descurainia sophia L. populations from Henan and Xinjiang, China

Descurainia sophia L. is a notorious weed in winter wheat field and has serious resistance to tribenuron-methyl. Xinjiang is a main wheat production region in China with no information on D. sophia resistance to tribenuron-methyl. Here, resistance levels of D. sophia populations to tribenuron-methyl from Xinjiang and Henan were investigated. In addition, homozygous mutation subpopulations of high resistant D. sophia populations from Xinjiang and Henan were generated and then cross-resistance and fitness cost were determined. Results showed that 5 out of 31 populations from Xinjiang developed resistance to tribenuron-methyl, including two high resistant populations (X30 and X31). While 10 out of 11 populations from Henan showed resistance to tribenuron-methyl, including three high resistant populations (H5, H6 and H7). X30 and X31 shared the same mutation type of Pro197Thr in ALS1, while the mutation type of ALS1 in H5, H6 and H7 were Pro197Ser, Pro197His and Pro197Ala, respectively. The homozygous mutation subpopulations (SX30, SX31, SH5, SH6, SH7) showed cross-resistance to flucarbazone-sodium, bensulfuron methyl and flumetsulam. Under monoculture condition, relative growth rates of SX30, SX31 were higher than susceptible population (SX13), while that in SH5, SH6, SH7 were almost same with SX13. When mix planted with SX13, SX30 and SX31 displayed weaker competitiveness than SX13, while SH5, SH6, SH7 showed stronger competitiveness than SX13. The results suggested that D. sophia from Xinjiang had low resistance frequency to tribenuron-methyl and the high resistant populations had fitness costs.