Category Archives: Annals of Applied Biology

Spatiotemporal dynamics of a palm weevils’ outbreak and susceptibility of peach palm (Bactris gasipaes Kunth) landraces in a germplasm bank in southwestern Colombia

Posted on 7 August 2023 by

This study investigated the population dynamics of the palm weevils Rhynchophorus palmarum and Dynamis borassi in a peach palm plantation in southwestern Colombia. We used pheromone traps and conducted palm censuses to analyse temporal and spatial patterns of the weevils. We found that R. palmarum outnumbered D. borassi during periods of high insect populations and observed synchronized population peaks related to the phenological stage of the peach palm. This study also highlighted the need for complementary control strategies and suggested a breeding programme based on identified genotypes for integrated pest management of palm weevils.

Abstract

The palm weevils Rhynchophorus palmarum and Dynamis borassi are prominent pest species in peach palms and coconut in Colombia. Nevertheless, knowledge of the population dynamics of these weevil species in the neotropical region is still scarce. In this study, we systematically sampled these weevils over 2 years using pheromone traps (1 trap ha⁻¹) in an experimental peach palm plantation under heavy weevil infestation in southwestern Colombia. Additionally, we censused the palms in a portion of the plantation (a peach palm germplasm bank) before and after the weevil monitoring. We analysed the data to elucidate sex-specific temporal and spatial patterns of both R. palmarum and D. borassi in a 19.13 ha area. Furthermore, we sought to detect peach palm landraces within the germplasm bank susceptible and resistant/tolerant to the weevil attack. During periods when insect populations were high, we observed that R. palmarum consistently outnumbered D. borassi. Specifically, we found that R. palmarum reached up to 80 insects trap⁻¹ month⁻¹, while D. borassi only reached around 30 insects trap⁻¹ month⁻¹ during the peak months. However, both species exhibited synchronous population peaks, which were not related to rainfall or temperature but rather to the phenological stage of the peach palm. Furthermore, the weevils had a highly aggregated spatial pattern; insect catchments were more prolific in areas where the landraces Nariño and Risaralda were sown. Moreover, the census evidenced that these two landraces were the most affected. Contrarily, weevil capture was overall low around the Guaviare landrace, this was the only landrace that exhibited an increase in stipes between census years. Our results highlight that complementary control strategies are needed to counteract sudden weevil population outbreaks, as pheromone traps are a good tool for monitoring but not for effective control. Furthermore, more importantly, a peach palm breeding programme based on the identified genotypes should be the basis for the integrated pest management of palm weevils.

Response to water‐deficit following waterlogging varies among ecotypes of subterranean clover (Trifolium subterraneum ssp. yanninicum), a waterlogging‐tolerant annual pasture legume

Posted on 3 August 2023 by

The annual pasture legume Trifolium subterraneum ssp. yanninicum exhibits high waterlogging tolerance. However, the ability of ssp. yanninicum genotypes to alter phenotype under soil moisture fluctuation (SMF) from waterlogged (WL) to water-deficit (WD), relative to a well-watered (WW) control, has not previously been evaluated. This study evaluated phenotypic plasticity under SMF for shoot and root relative growth rates (RGR) and its effects on other traits, including rhizobia nodulation, root morphology and leaf phyto-oestrogen content, in three contrasting ecotypes of ssp. yanninicum. The scientific strength of this paper arises from the imposition of SMF on a WL tolerant legume and the finding that stable shoot growth throughout SMF was attributable to a highly plastic response with capacity for rapid shoot and root growth to post-WL stress in a drying soil profile.

Abstract

The pasture legume Trifolium subterraneum ssp. yanninicum L. is waterlogging tolerant, but water-deficit (WD) susceptible. The interactive effect of waterlogged (WL) and WD (soil moisture fluctuation [SMF]) results in a severe stress impact. We studied three diverse ecotypes to identify traits associated with adaptation to SMF. Ecotypes were established in a glasshouse with two treatments imposed at 21 days: well-watered (WW–WW; 80% field capacity [FC]) and WL to WD (WL–WD). For WL–WD, pots were WL for 28 days (Harvest I), and then transitioned to WD (drained to 40% FC) and maintained for 10 days (Harvest II). For shoot relative growth rates (RGR) at Harvest I, WL had relatively little impact, although there was a greater reduction for Ecotype A (80% of WW) than Ecotypes B (92%) and C (87%). However, between Harvests I and II, the impact of WL–WD varied among ecotypes with Ecotype A being less affected (75% of WW–WW) than Ecotypes B (57%) and C (63%). For root RGR at Harvest I, WL resulted in a greater reduction for Ecotype A (52% of WW) than Ecotypes B (77%) and C (74%), while for WL–WD between Harvests I and II, Ecotype A showed a large increase (117% of WW–WW) compared to Ecotypes B (95%) and C (87%). In conclusion, the response to WD following WL varied among ecotypes, which demonstrates contrasting adaptation responses to SMF unrelated to WL tolerance. High yield under WL together with capacity for rapid growth post-WL in a drying soil profile could enhance adaptation to SMF.

Meiotic abnormalities in sugarcane (Saccharum spp.) and parental species: Evidence for peri‐ and paracentric inversions

Posted on 1 August 2023 by

Modern cultivars of sugarcane have a genome of interspecific constitution (polyploid and aneuploid) produced by human intervention. We have investigated the meiotic behaviour of representatives of the parental species (Saccharum officinarum and Saccharum spontaneum) and the SP80-3280 modern cultivar. Although bivalent associations were prevalent at diakinesis (together with 2–4 univalents), there was a clear evidence of meiotic irregularities incidence, including peri- and paracentric inversions in the modern cultivar.

Abstract

The modern cultivars of sugarcane (Saccharum spp.) are highly polyploid and accumulate aneuploidies due to their history of domestication, genetic improvement and interspecific hybrid origin involving the domesticated sweet species Saccharum officinarum (‘noble cane’) and the wild Saccharum spontaneum, both with an evolutionary history of polyploidy. The first hybrids were backcrossed with S. officinarum, and selection from progenies in subsequent generations established the genetic basis of modern cultivars. Saccharum genome complexity has inspired several molecular studies that have elucidated aspects of sugarcane genome constitution, architecture and cytogenetics. Herein, we conducted a comparative analysis of the meiotic behaviour of representatives of the parentals S. officinarum and S. spontaneum, and the commercial variety, SP80-3280. S. officinarum, an octoploid species, exhibited regular meiotic behaviour. In contrast, S. spontaneum and SP80-3280 exhibited several abnormalities from metaphase I to the end of division. We reported and typified, for the first time, the occurrence of peri- and paracentric inversions. Using in-situ hybridisation techniques, we were able to determine how pairing association occurred at diakinesis, the origin of lagging chromosomes and, in particular, the mitotic chromosome composition of SP80-3280. Interestingly, S. spontaneum and recombinant chromosomes showed the most marked tendency to produce laggards in both divisions. Future attempts to advance knowledge on sugarcane genetics and genomics should take meiotic chromosome behaviour information into account.

The effect of silicon on the antioxidant system of tomato seedlings exposed to individual and combined nitrogen and water deficit

Posted on 24 July 2023 by

This paper shows that silicon mitigated some of the adverse effects of combined water and nitrogen deficit, increasing several traits related to plant growth. The combined deficit, silicon-treated plants could efficiently modulate their antioxidant system. Better performance seems to be related to the root's antioxidant system.

Abstract

Exploring sustainable strategies for improving crop water and nitrogen use efficiency is essential. Silicon (Si) has been reported as a beneficial metalloid for plants since it alleviates several abiotic stresses (including drought) by triggering the plants' antioxidant system. However, its role in mitigating the negative impact of nitrogen (N) deficit alone or when combined with water (W) deficit is not well studied. This study applied 0 or 2 mM of Na₂SiO₃ to 3-week-old tomato cv. Micro-Tom seedlings that were grown under the following conditions: control (CTR; 100%N + 100% Field Capacity), N deficit (N; 50% N + 100% Field Capacity), water deficit (W; 100% N + 50% Field Capacity) or combined stress (N + W; 50% N + 50% Field Capacity). The Si effect on tomato plant growth depended on the type of stress. Si could only alleviate stress caused by N + W deficit resulting in a higher root dry weight (by 28%), total dry weight (by 23%) and root length (by 37%). Alongside this, there was an increase in the antioxidant (AOX) system activity with the root activity of ascorbate peroxidase and catalase enzymes being enhanced by 48% and by 263%, respectively. Si application also enhanced AOX enzyme activity when tomato plants were subjected to individual deficits but to a lesser extent. In conclusion, Si-treated tomato plants could efficiently modulate their AOX networks in a situation of combined N and water limitation, thus mitigating some of the adverse effects of this combined stress.

Molecular identification of ‘Candidatus Phytoplasma palmicola’ associated with coconut lethal yellowing in Equatorial Guinea

Posted on 14 July 2023 by

A high mortality of coconut palms was observed in the coastal areas of Equatorial Guinea. Molecular analyses on 16S rRNA and secA genes detected ‘Candidatus Phytoplasma palmicola’ subgroup 16SrXXII-A. Strict monitoring and surveillance procedures for early detection of the pathogen are strongly recommended to reduce its impact and further spread in the country.

Abstract

During the past two decades, a high mortality of coconut palms was observed in the coastal areas of Equatorial Guinea. Reportedly, the palm population has been reduced by 60%–70%, and coconut production has decreased accordingly. To identify the cause of the mortality, a survey was carried out in April 2021 in various localities of the coconut belt. Molecular analyses carried out on 16S rRNA and secA genes detected phytoplasma presence in the majority of the samples. Sequencing and BLAST search of the 16S rRNA gene sequences showed >99% identity of the detected phytoplasmas to ‘Candidatus Phytoplasma palmicola’. The RFLP analyses of 16S ribosomal gene using Tru1I and TaqI enzymes led to assign these phytoplasmas to subgroup 16SrXXII-A. In all samples that tested positive, including one from a hybrid coconut palm and two from oil palm the same phytoplasma was identified. The phylogenetic analyses of 16S rRNA and secA genes confirmed respectively 99.98%–100% and 97.94%–100% identity to ‘Ca. P. palmicola’. RFLP analyses using MboII enzyme on the secA gene amplicon differentiated the phytoplasma found in Equatorial Guinea from those present in Ghana and Ivory Coast. The Equatorial Guinean phytoplasma strain resulted to be identical to the strains from Mozambique, confirming the presence of a geographic differentiation among phytoplasma strains in the coastal areas of Western and Central Africa. The identified phytoplasma is different from the ‘Ca. P. palmicola’ strains found in Ghana and Ivory Coast and represents the first identification a 16SrXXII-A strain in Equatorial Guinea and in Central Africa. Strict monitoring and surveillance procedures for early detection of the pathogen are strongly recommended to reduce its impact and further spread in the country and permit the recovery of coconut plantations.

Silicon dioxide in the defence induction of soybean against Spodoptera frugiperda

Posted on 14 July 2023 by

Silicon dioxide applied via foliar on soybean plants increases larval and pupal phase of Spodoptera frugiperda. The increase in the concentration of silicon dioxide applied increases the wear of the mandible of the caterpillar making it difficult to feed.

Abstract

Silicon can increase the natural defence of plants against stresses including herbivorous insects. Silicon dioxide (SiO₂) is one of the forms of silicon, and despite its wide use in the industrial sector, its use in agriculture is still poorly adopted. The aim of this study was to evaluate the effectiveness of foliar application of SiO₂ in inducing defence against Spodoptera frugiperda in soybean. The experiments were conducted in a completely randomised design with four treatments (0%, 1%, 2.5%, and 5% of SiO₂). The effect on cannibalism, biological parameters (mortality, duration of the larval stage, duration of the pupal stage and pupal weight) and wear on the mandible of S. frugiperda were evaluated. The foliar silicon content was also determined. The supply of SiO₂ prolonged the duration of the larval and pupal stages of the S. frugiperda by 0.56 and 0.17 days for each 1% of SiO₂ applied, respectively. The use of SiO₂ at 5% increased the mortality rate of caterpillars in the larval stage by approximately 25%. There was no effect of SiO₂ application on cannibalism and weight of S. frugiperda pupae. There was wear on the caterpillars' jaws in the third and fourth instar at the highest SiO₂ concentration. The application of SiO₂ promoted greater accumulation of silicon in soybean leaves. It is concluded that the foliar application of SiO₂ affects the biological performance of S. frugiperda through the induction of defence in the soybean crop and presents itself as a promising strategy in integrated pest management programmes.

Nematicidal effect of an Amaranthus hypochondriacus L. cystatin (AhCPI) on the root‐knot nematode Meloidogyne incognita (Kofoid and White) Chitwood

Posted on 10 July 2023 by

Nematicidal effect of an Amaranthus hypochondriacus L. cystatin (AhCPI) on the root-knot nematode Meloidogyne incognita.

Abstract

The root-knot nematode Meloidogyne incognita is one of the most damaging plant parasitic nematodes in the world. In this study, the effect of cystatin from Amaranthus hypochondriacus (AhCPI) as a potential control agent for M. incognita was explored. In vitro bioassays demonstrated that AhCPI affects the growth and development of eggs and the infectivity of juveniles (J2) of M. incognita, such as mortality and slower development, showing characteristic tissue damage. Mortality levels were quantified by Probit analysis, estimating LC₅₀s of 1.4 mg/mL for eggs and 0.028 mg/mL for J2. In planta bioassays showed that infected tomato seedlings treated with 0.056 mg/mL of AhCPI showed a 60% reduction in the number of galls, as compared with untreated J2-inoculated seedlings. Under greenhouse conditions, three applications of 10 mL of AhCPI (1.4 mg/mL) in the soil around the stem of M. incognita-infected tomato plants, reduced the number of galls by 93 ± 8%, as compared to the control M. incognita-infected plants. The application of AhCPI to the infected plants increased the yield (10.7%) of harvested tomato fruits, as compared to infected plants. These results show the potential of AhCPI for the control of M. incognita in tomato plants.

Boron foliar supplementation as a strategy to attenuate drought stress in soybean

Posted on 26 June 2023 by

Extra boron alleviates the effects of drought stress in soybean.

Abstract

Drought is the major abiotic stress that limits growth, development and yield of crops worldwide. In this scenario, mineral nutrients, such as boron (B), have been promising for increasing the tolerance of plants to abiotic stresses because of their physiological roles in plants. We aimed to evaluate the benefits of foliar supplementation of B in either relieving or reducing the physiological damages caused by water stress in soybean (Glycine max L.). A greenhouse trial was carried out in a 2 × 3 factorial scheme, with two water conditions (well-watered and drought stress) and three doses of B (0, 150 and 300 mg B L⁻¹). Foliar application of B was before inducing the water stress, which remained for 20 days during vegetative stage. Plants were evaluated at three moments, according to the water conditions: maximum stress, rehydration and just before harvesting. The levels of hydrogen peroxide and lipid peroxidation increased in soybean leaves and roots under water stress, resulting in impaired plant growth. However, the foliar supplementation with B before the stress increased activities of the antioxidant enzymes and reduced the levels of stress markers. Furthermore, B applied foliar increased the nutrient concentration in the leaves of plants and stimulated root growth, which resulted in higher harvest index related to yield. The foliar application of B has shown as an alternative management to mitigate the damages caused by drought stress in soybean.

Incidence and genetic diversity of raspberry bushy dwarf virus (RBDV) in Rubus spp. in Turkey

Posted on 22 June 2023 by

Raspberry bushy dwarf virus (RBDV), recently renamed to Idaeovirus rubi, is one of the most common viruses infecting Rubus species worldwide but there is still a limited number of genome sequences available in the GenBank database and the majority of the sequences include partial sequences of RNA-1 and RNA-2. The distribution and incidence of RBDV in main raspberry and blackberry growing provinces in Turkey were monitored during 2015–2019 and 537 Rubus spp. samples were tested by both DAS-ELISA and RT-PCR. Among the tested samples, 36 samples tested positive for RBDV by DAS-ELISA and 67 samples by RT-PCR. There was relatively low nucleotide diversity among the Turkish isolates. Turkish isolates shared 93%–97.7%, 84.3%–98.9%, and 85%–99.2% nucleotide sequence identities with available sequences in the GenBank, in partial RNA-1, movement protein (MP) and coat protein (CP) genes, respectively. In the phylogenetic tree constructed for RNA-1, MP, and CP sequences, all Turkish raspberry isolates were clustered in a distinct clade. However, the blackberry isolates showed considerable variation in nucleotide sequences and were placed in three distinct groups. The divergent blackberry isolates showed high variability in MP (84.5%–89.3%) and CP (85.5%–89.7%) regions and were placed in a distinct group. The rest of the blackberry isolates clustered together with sweet cherry RBDV isolates adjacent to the grapevine clade or together with raspberry isolates. The comparative analysis conducted on three RNA segments of RBDV highlighted the high sequence diversity of Turkish RBDV isolates.

Abstract

Raspberry bushy dwarf virus (RBDV), recently renamed to Idaeovirus rubi, is one of the most common viruses infecting Rubus species worldwide but there is still a limited number of genome sequences available in the GenBank database and the majority of the sequences include partial sequences of RNA-1 and RNA-2. The distribution and incidence of RBDV in main raspberry and blackberry growing provinces in Turkey were monitored during 2015–2019 and 537 Rubus spp. samples were tested by both DAS-ELISA and RT-PCR. Among the tested samples, 36 samples tested positive for RBDV by DAS-ELISA and 67 samples by RT-PCR. There was relatively low nucleotide diversity among the Turkish isolates. Turkish isolates shared 93%–97.7%, 84.3%–98.9%, and 85%–99.2% nucleotide sequence identities with available sequences in the GenBank, in partial RNA-1, movement protein (MP) and coat protein (CP) genes, respectively. In the phylogenetic tree constructed for RNA-1, MP, and CP sequences, all Turkish raspberry isolates were clustered in a distinct clade. However, the blackberry isolates showed considerable variation in nucleotide sequences and were placed in three distinct groups. The divergent blackberry isolates showed high variability in MP (84.5%–89.3%) and CP (85.5%–89.7%) regions and were placed in a distinct group. The rest of blackberry isolates clustered together with sweet cherry RBDV isolates adjacent to the grapevine clade or together with raspberry isolates. The comparative analysis conducted on three RNA segments of RBDV highlighted the high sequence diversity of Turkish RBDV isolates. This study also emphasizes the importance of regular monitoring of RBDV infections in Turkey, with special regard to those Rubus spp. and grapevine accessions employed in conservation and selection programmes. In particular, the presence of new RBDV genetic variants and infection of Rubus species must be taken into account to choose a correct detection protocol and management strategy.

Begomovirus diversity in tomato crops in Costa Rica

Posted on 21 June 2023 by

Begomoviruses, including PepGMV, ToYMoV, ToLCSiV and TYLCV, were detected in Costa Rica, presenting challenges due to their recombination and wide host range. However, understanding of TYLCV's spread and the distribution of other bipartite begomoviruses in the country remains limited. In a study analyzing 429 georeferenced tomato samples, TYLCV was found in all six provinces, with varying prevalence. Alajuela, Cartago, and Heredia were the most affected regions. The presence of TYLCV correlated with the presence of the B. tabaci MED whitefly, offering valuable insights for disease management and crop enhancement strategies.

Abstract

Begomoviruses (Geminiviridae family) are characterized by their high recombination rate and a wide range of hosts, making their control difficult. In Costa Rica, various species of bipartite begomoviruses have been reported, which are Pepper golden mosaic virus (PepGMV), Tomato yellow mottle virus (ToYMoV), Tomato leaf curl Sinaloa virus (ToLCSiV) and the monopartite begomovirus Tomato yellow leaf curl virus (TYLCV). Since the TYLCV first report in Costa Rica, neither additional knowledge has been produced on how this begomovirus has spread in the country's territory nor on the distribution of the other bipartite species. A total of 429 tomato samples collected during the years 2015–2016 were used to study these aspects. Each sample was georeferenced and analysed with various techniques such as nucleic acid hybridization, polymerase chain reaction (PCR) and sequencing for the begomoviruses previously reported in Costa Rica. It was found that the presence/absence of the different species can vary, depending on the province. TYLCV is present in the six provinces analysed in this work, with a proportion from 3.7 to 86.6 per cent. Alajuela, Cartago, and Heredia are the provinces most affected by tomato-infecting begomoviruses. Fourteen different haplotypes of TYLCV were detected, but all were identified as TYLCV-IL. The distribution of TYLCV was related to the presence of the whitefly Bemisia tabaci MED, especially in the country's main tomato production areas. This information allows the phytosanitary surveillance services to develop strategies for the integrated management of the disease and to contribute data to the genetic improvement programmes of the crop.