Mycorrhization in trees: ecology, physiology, emerging technologies and beyond

Mycorrhization has been an integral part of plants since colonization by the early land plants. Over decades, substantial research has highlighted its potential role in improving nutritional efficiency and growth, development and survival of crop plants. However, the focus of this review is trees. Evidence have been provided to explain ecological and physiological significance of mycorrhization in trees. Advances in recent technologies (e.g., metagenomics, artificial intelligence, machine learning, agricultural drones) may open new windows to apply this knowledge in promoting tree growth in forest ecosystems. Dual mycorrhization relationships in trees and even triple relationships among trees, mycorrhizal fungi and bacteria offer an interesting physiological system to understand how plants interact with other organisms for better survival. Besides, studies indicate additional roles of mycorrhization in learning, memorizing and communication between host trees through a common mycorrhizal network (CMN). Recent observations in trees suggest that mycorrhization may even promote tolerance to multiple abiotic (e.g., drought, salt, heavy metal stress) and biotic (e.g. fungi) stresses. Due to the extent of physiological reliance, local adaptation of trees is heavily impacted by the mycorrhizal community. This knowledge opens the possibility of a non-GMO avenue to promote tree growth and development. Indeed, mycorrhization could impact growth of trees in nurserys and subsequent survival of the inoculated trees in field conditions. Future studies might integrate hyperspectral imaging and drone technologies to identify tree communities that are deficient in nitrogen and spray mycorrhizal spore formulations on them.

Comparative cryopreservation of indian wild orange (Citrus indica Tanaka) embryonic axes

BACKGROUND

Indian Wild Orange (Citrus indica Tanaka) is an endangered and endemic species from northeast India for which effective ex situ conservation strategies, including embryo cryopreservation, are urgently needed.

MATERIALS AND METHODS

Desiccation tolerance and cryopreservation ability for embryonic axes of Citrus indica was determined using three techniques (air desiccation-freezing, PVS2 vitrification-freezing and encapsulation-dehydration-freezing). Success was assessed as survival and recovery in vitro.

RESULTS

Successful cryopreservation of embryonic axes was achieved using all three methods, with the highest survival achieved when using air desiccation-freezing (90%) followed by encapsulation-dehydration (85%) and PVS2 vitrification cryopreservation (80%). Regeneration levels were lower than survival levels for all three proceedures. Post-cryo regeneration success was: encapsulation-dehydration (64%) > air desiccation-freezing (55%) > PVS2 vitrification (52%).

CONCLUSION

Although there was relatively high post-cryopreservation recovery growth obtained using all the three techniques, the air desiccation-freezing technique is preferred, as it is a simple, practical and reproducible technique for the long-term cryobanking of this important wild species. Doi: 10.54680/fr23310110512.

Challenges in bioinformatics approaches to tumor mutation burden analysis

Several immune checkpoint inhibitors (ICIs) have already been introduced into clinical practice or are in advanced phases of clinical experimentation. Extensive efforts are being made to identify robust biomarkers to select patients who may benefit from treatment with ICIs. Tumor mutation burden (TMB) may be a relevant biomarker of response to ICIs in different tumor types; however, its clinical use is challenged by the analytical methods required for its evaluation. The possibility of using targeted next-generation sequencing panels has been investigated as an alternative to the standard whole exome sequencing approach. However, no standardization exists in terms of genes covered, types of mutations included in the estimation of TMB, bioinformatics pipelines for data analysis, and cut-offs used to discriminate samples with high, intermediate or low TMB. Bioinformatics serve a relevant role in the analysis of targeted sequencing data and its standardization is essential to deliver a reliable test in clinical practice. In the present study, cultured and formalin-fixed, paraffin-embedded cell lines were analyzed using a commercial panel for TMB testing; the results were compared with data from the literature and public databases, demonstrating a good correlation. Additionally, the correlation between high tumor mutation burden and microsatellite instability was confirmed. The bioinformatics analyses were conducted using two different pipelines to highlight the challenges associated with the development of an appropriate analytical workflow.

Storage Behavior and Cryopreservation of Citrus cavaleriei, an Endangered, Cold-resistant Species of Northeast India with Exceptionally Large Seeds

BACKGROUND

Ichang Papeda (Citrus cavaleriei H.Lév. ex Cavalerie) is a wild and endangered species of NE India that requires urgent preservation of its genetic resources.

OBJECTIVE

To characterize the storage physiology of the seeds and to cryopreserve the embryo and embryonic axis (EA).

MATERIALS AND METHODS

The morphology and storage physiology of the seeds were determined, and the cryopreservation of embryos and EA attempted using various techniques (viz., air desiccation-freezing, vitrification and encapsulation-dehydration).

RESULTS

Weighing up to 4 g, seeds of Citrus cavaleriei are the largest known in the genus. Based on estimates using the seed coat ratio - seed mass (SCR-SM) model there was a very high probability of seed desiccation intolerance, which was validated physiologically; seeds lost vigour on drying below 30% moisture content (MC) and no seeds germinating after drying to <12% MC. Embryos and EAs could be air dried to 25-30% MC and cryopreserved with c. 50% survival. In contrast, EA optimally exposed to PVS2 (20 min) or encapsulated, sucrose pretreated (0.5 M, 24 h) and dehydrated (6 h) had c. 40% survival after cryopreservation.

CONCLUSION

Citrus cavaleriei produces large, recalcitrant seeds that can, nevertheless, be cryopreserved as embryos or isolated EA after air drying to c. 25-30% MC; encapsulation-dehydration and vitrification provide alternative options for the cryopreservation of EA.

Long-term, large scale banking of citrus species embryos: comparisons between cryopreservation and other seed banking temperatures

The long-term, large scale application of embryo cryopreservation has been assessed rarely and comparisons of viability loss for partially dried material with conventional seed bank storage conditions infrequently made. Five citrus species were cryopreserved following air drying of embryos (seed minus the testa) and embryonic axes: rough lemon (Citrus jambhiri), pommelo (C. grandis), mandarin (C. reticulata), citron (C. medica) and kagzi lime (C. aurantifolia). Although drying rates to c. 10 percent moisture content (MC) were approximately 10-times faster for isolated axes compared to embryos, the optimum MCs for cryopreservation were generally similar within a species, varying from c. 10 percent (C. jambhiri) to c. 20 percent (C. medica). Nonetheless, the hydration window for cryopreservation of the axis was usually wider than for the embryo. For all species, embryo or axis survival after cryopreservation ranged from 65 to 96 percent (C. medica axes), producing normal healthy seedlings from embryos and plantlets from axes without intervening callus growth in vitro. Whilst partially dried embryos of all five species survived fully liquid nitrogen vapour storage for 120 days, viability loss was rapid at -20 degree C, 5 degree C and ambient temperature, with a maximum interpolated half-life across these temperatures of c. 80 days for C. grandis at 5 degree C. The developed cryopreservation protocols were applied routinely to cryobank 377 accessions of Citrus germplasm from field genebanks, farmer's orchards, semi-wild and wild sources. After an average of 6.3 to 8.4 years cryo-storage, between 69 and 81 percent of accessions per species retained > 70 percent of the viability after desiccation. The results provide irrevocable evidence for the importance of cryopreservation for the banking of seeds of higher plants.

Addiction severity index composite scores as predictors for sexual-risk behaviors and drug-use behaviors in drug-using pregnant patients

BACKGROUND

HIV sexual-risk and drug-use behavior predictors have been studied in non-pregnant but not pregnant drug-dependent populations.

OBJECTIVE

Examine the ability of the ASI composite scores to predict HIV sexual- and drug-risk scores as well as the individual items of a modified version of the Risk Assessment Battery in drug-using pregnant women.

METHODS

Pregnant women (N = 76) completing pretreatment ASI and HIV-risk questionnaires.

RESULTS

The Legal composite score was the sole significant predictor of the sexual-risk score, with a 1 SD increase in the Legal composite score resulting in a 24% increase in sexual-risk, p < .001. The Medical, Drug, and Legal composite scores were each significant predictors of the drug-risk score, with a 1 SD increase resulting in a 31% decrease, and 121% and 73% increases, respectively, in drug-risk, all ps < .05.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Drug-using pregnant women and their fetuses are vulnerable to the consequences of both sexual-risk behaviors and drug-use. The ASI may help screen such patients for HIV sexual-risk and drug-use behaviors as a first step in tailoring treatment to address these issues.

Two mouse retinal degenerations caused by missense mutations in the beta-subunit of rod cGMP phosphodiesterase gene

We report the chromosomal localization, mutant gene identification, ophthalmic appearance, histology, and functional analysis of two new hereditary mouse models of retinal degeneration not having the Pde6brd1("r", "rd", or "rodless") mutation. One strain harbors an autosomal recessive mutation that maps to mouse chromosome 5. Sequence analysis showed that the retinal degeneration is caused by a missense point mutation in exon 13 of the beta-subunit of the rod cGMP phosphodiesterase (beta-PDE) gene (Pde6b). The gene symbol for this strain was set as Pde6brd10, abbreviated rd10 hereafter. Mice homozygous for the rd10 mutation showed histological changes at postnatal day 16 (P16) of age and sclerotic retinal vessels at four weeks of age, consistent with retinal degeneration. Retinal sections were highly positive for TUNEL and activated caspase-3 immunoreactivity, specifically in the outer nuclear layer (ONL). ERGs were never normal, but rod and cone ERG a- and b-waves were easily measured at P18 and steadily declined over 90% by two months of age. Protein extracts from rd10 retinas were positive for beta-PDE immunoreactivity starting at about the same time as wild-type (P10), though signal averaged less than 40% of wild-type. Interestingly, rearing rd10 mice in total darkness delayed degeneration for at least a week, after which morphological and functional loss progressed irregularly. With the second strain, a complementation test with rd1 mice revealed that the retinal degeneration phenotype observed represents a possible new allele of Pde6b. Sequencing demonstrated a missense point mutation in exon 16 of the beta-subunit of rod phosphodiesterase gene, different from the point mutations in rd1 and rd10. The gene symbol for this strain was set as Pde6bnmf137, abbreviated nmf137 hereafter. Mice homozygous for this mutation showed retinal degeneration with a mottled retina and white retinal vessels at three weeks of age. The exon 13 missense mutation (rd10) is the first known occurrence of a second mutant allele spontaneously arising in the Pde6b gene in mice and may provide a model for studying the pathogenesis of autosomal recessive retinitis pigmentosa (arRP) in humans. It may also provide a better model for experimental pharmaceutical-based therapy for RP because of its later onset and milder retinal degeneration than rd1 and nmf137.

Gastric acid study in patients operated on for perforated duodenal ulcer

OBJECTIVES

To determine the acid secretory status of patients operated on for perforated duodenal ulcer, with or without prior history suggestive of acid-peptic disease.

METHOD

Basal and peak acid output were measured in 48 patients with perforated duodenal ulcer who were treated by simple closure alone, 10 patients with uncomplicated chronic duodenal ulcer and 30 normal controls. Patients operated on for perforated duodenal ulcer were analyzed according to presence (or absence) and duration of prior history of acid-peptic disease.

RESULTS

Peak acid output was similar in controls and patients with perforated duodenal ulcer with no prior symptoms. However, patients with prior symptoms had significantly higher peak acid output, similar to those with uncomplicated duodenal ulcer.

CONCLUSION

Patients with perforated duodenal ulcer with no antecedent history of acid-peptic disease have normal gastric acid output. These patients may therefore have other etiological factors for their ulcers.