Morphological and Biochemical Changes in the Mediterranean Cereal Cyst Nematode (Heterodera latipons) during Diapause.

The cereal cyst nematode (Heterodera latipons) is becoming an economically important species in global cereal production as it is being identified in many new cereal cultivated areas and causes significant losses. Consequently, understanding its biology becomes crucial for researchers in identifying its vulnerabilities and implementing effective control measures. In the current study, different morphological and biochemical changes of H. latipons cysts containing eggs with infective juveniles from a barley field in Jordan were studied during the summer of 2021, at two sample dates. The first, at the harvest of the cereal crop (June 2021), when the infective second-stage juveniles (J2s) were initiating diapause, and the second, before planting the sequent cereal crop (late October 2021), when the J2s were ending diapause. The studied population was characterized morphologically and molecularly, showing 98.4% molecular similarity to both JOD from Jordan and Syrian "300" isolates of H. latipons. The obtained results and observations revealed that there were dramatic changes in all the investigated features of the cysts and eggs they contained. Morphological changes such as cyst color, sub-crystalline layer, and thickness of the rigid eggshell wall were observed. A slight change in the emergence time of J2s from cysts was observed without any difference in the number of emerged J2s. The results of biochemical changes showed that the total contents of carbohydrates, glycogen, trehalose, glycerol, and protein were higher in cysts collected in October when compared to those cysts collected in June. The SDS-PAGE pattern indicated the presence of a protein with the size of ca. 100 kDa in both sampling dates, whereas another protein (ca. 20 kDa) was present only in the cysts of October. Furthermore, the expression of trehalase (tre) gene was detected only in H. latipons collected in October. The outcomes of this study provide new helpful information that elucidates diapause in H. latipons and may be used for the implementation of new management strategies of cyst nematodes.

Bioinformatics analysis of ubiquitin expression protein gene from Heterodera latipons.

Ubiquitin expression protein DNA clone (Hl-UBI) was isolated from Heterodera latipons collected from North Jordan. Its sequence of 285 nucleotides was also determined and deposited in the GeneBank. The 285-bp open reading frame coded for 76-amino acid protein having two domains; the ubiquitin domain and the C terminal extension. The first 59 amino acids were predicted with the ubiquitin domain with identity percentages of 78% to ubiquitin of H. schachtii, 77% to polyubiquitin of Globodera pallida, 74% to ubiquitin of Globodera rostochiensis and 72% to ubiquitin of Heterodera glycines. The other domain at the C-terminus, containing 17 amino acids, showed no homology to any known protein. Sequence analysis showed a calculated encoding amino acids molecular weight of 8.77 kDa, theoretical isoelectric point = 4.76, negatively charged residues = 12, positively charged residues = 9, extinction coefficient = 1490, estimated half-life = 30 h, instability index = 32.51 and grand average of hydropathicity = -0.537. The demonstrated subcellular localization analysis of cytoplasm, cell nucleus, mitochondrion, cell skeleton and plasma membrane of Hl-UBI protein occupied about 52.20, 21.70, 17.40, 4.30 and 4.30%, respectively. Sequence, homology and structural analysis confirmed that Hl-UBI gene was highly conserved during evolution and belonged to ubiquitin gene family.

Draft Genome Sequence of the Plant Growth-Promoting Pseudomonas punonensis Strain D1-6 Isolated from the Desert Plant Erodium hirtum in Jordan.

Pseudomonas punonensis strain D1-6 was isolated from roots of the desert plant Erodium hirtum, near the Dead Sea in Jordan. The genome of strain D1-6 reveals several key plant growth-promoting and herbicide-resistance genes, indicating a possible specialized role for this endophyte.

Morphological and morphometrical analysis of Heterodera spp. populations in Jordan.

Phenotypic diversity of five Jordanian populations of cyst nematodes, Heterodera spp. collected from five regions from Jordan (Ar-Ramtha, Madaba, Dana, Al-Karak, and Jerash) was investigated. Soil samples were collected from one representative field in each region. Morphological and morphometrical characteristics revealed that Heterodera latipons is dominated in cereal fields at Ar-Ramtha, Madaba, Dana and Al-Karak regions and Heterodera schachtii in Jerash. Cysts populations from all cereal fields had bifenestrate vulval cone and a strong underbridge. Wherever, cysts of the cabbage population had ambifenestrate vulval cone with long vulval slit. The bullae were absent in Ar-Ramtha, Madaba and Dana populations, but present in Al-Karak and Jerash. Based on 12 morphometrical characters, the first three functions in canonical discriminant analysis accounted 99.3% of the total variation. Distance from dorsal gland duct opening to stylet base, underbridge length, a = L/W (body length/midbody width) and length of hyaline tail tip had strong and significant contributions in the first function. While the second function was strongly influenced by length of hyaline tail, fenestral length, fenestral width and tail length. However, the third canonical discriminate function was found to be influenced by stylet length, fenestral length, a = L/W (body length/midbody width) and underbridge width. The graphical representation of the distribution of the samples showed that the first canonical discriminant function clearly separated H. schachtii from Jerash from other populations. Whereas, H. latipons collected from Madaba and Dana were clearly separated in the second function. The results indicated that differences at morphological and morphometrical levels revealed diverse populations of Heterodera spp. in Jordan.

Phosphonate fertilizers suppressed root knot nematodes Meloidogyne javanica and M. incognita.

The efficacy of the phosphonate fertilizers, Calphos(®) (a.i. calcium phosphonate), Magphos(®) (a.i. magnesium phosphonate and potassium phosphonate) and Phosphoros(®) (a.i. potassium phosphonate) against two species of root knot nematodes (RKN), Meloidogyne javanica and M. incognita is evaluated. Laboratory experiments showed that Calphos(®), Magphos(®) and their main components inhibited egg hatching and caused 100% mortality of the second stage juveniles (J2s) of the two RKN species; the hatching inhibition effects persisted after transferring the egg masses of both species to water. However, Phosphoros(®) (0.5%) did not suppress egg hatching or the survival of J2s of both RKN species. No hatching occurred when egg masses were treated for one week with the nematicide Vydate L(®) (2 ml/l), however, J2s hatched when the Vydate L(®) treated egg masses were moved to water. The glasshouse study indicated that Magphos(®), Calphos(®) and Phosphoros(®) reduced root galling caused by M. javanica by 98, 66 and 47%, respectively, in comparison to the untreated controls. Magphos(®) resulted in the lowest number of root galls formed by M. incognita, the reduction was 84%. In contrast, Calphos(®) and Phosphoros(®) reduced galling by 47 and 39%, respectively. The Magphos(®) treatment resulted in the lowest numbers of egg masses and the lowest reproductive factor (RF) of both nematode species. However, plants treated with Phosphoros(®) resulted in higher foliage weights compared with the application of the other two fertilizers and the untreated plants.

Diversity and distribution of entomopathogenic nematodes (Nematoda: Steinernematidae, Heterorhabditidae) and their bacterial symbionts (gamma-Proteobacteria: Enterobacteriaceae) in Jordan.

Until now, only a few systematic surveys of entomopathogenic nematodes (EPN) have been conducted in Middle Eastern countries. Many of the recovered EPN species in this region have shown to own distinctive qualities that enable their survival in unique environments, such as high temperatures and low moisture levels tolerance. These new species and strains, with unique environmental tolerances, are more suitable for their consideration in pest management programs in xerophytic regions. With this background in mind, we recently conducted a survey of EPN in Jordan. This study records for the first time the diversity and distribution of these nematodes and their bacterial symbionts in this country. Jordan's three geographic regions: (1) the highlands, (2) Jordan valley and (3) the desert region were sampled. Within each region, natural habitats and agricultural regions characteristic to each region were considered for sampling purposes. Four EPN species including three Steinernema and one Heterorhabditis were recovered. Nematodes were identified using a combination of molecular markers and classic morphological diagnostic tools. Bacterial symbionts were identified by analysis of 16S rRNA sequences. Abiotic characteristics such as soil type, soil pH, and elevation were also recorded. We herein report the diversity of EPN species in Jordan and discuss their potential in Biocontrol and IPM programs for this country.