Variation in Trichome Types and Density Mediates Plant-Herbivore Interactions in Two Cucurbitaceae Members

Plant structural defenses such as trichomes and spines exert a significant selection pressure on insect herbivores. However, how species variation affects structural defense trait expression in closely related species is less understood. Through our studies, we tried to dissect the role of trichomes in mediating plant-insect interactions, in two non-model cultivated species in Cucurbitaceae: Lageneria siceraria, and Cucumis sativa family, and Trichoplusia ni as our major herbivore of interest. We observed that species differed in their attractiveness to different herbivores and their feeding behavior in common garden experiment. To tease apart structural and chemical defenses and their independent roles in these interactions, we first used a desktop electron microscope (SNE-4500 Plus Tabletop), to identify, quantify and measure trichome related traits including their morphology and density. We found that C. sativa has significantly lower number of trichomes as compared to L. siceraria, regardless of trichome type and leaf surface. We then followed this with manipulated diet experiments and found that trichomes from these two species differentially affected growth and development of T.ni, and also confirmed that trichomes from L. siceraria were also effective in repelling T.ni, a behavior we observed in common garden experiments. Taken together, we show that trichome variation is an effective defense strategy in L. siceraria against herbivores with consequences for their survival

Impact of Incident Cancer on Coronary Artery Disease-Related Concomitant Medication Adherence, Short-Term Health and Economic Outcomes Among Elderly Medicare Beneficiaries with Coronary Artery Diseas

Coronary artery disease (CAD) is one of the most burdensome chronic conditions in the elderly. The two key goals of long-term management of CAD are (i) to reduce symptoms and ischemia and (ii) prevent myocardial infarction and death, by lowering lipids and blood pressure. Of all the risk reduction strategies, use and adherence to concomitant pharmacotherapy with statins and beta-blockers, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) have been shown to be highly effective and has become the cornerstone of CAD management. However, adherence to concomitant pharmacotherapy can be influenced by many factors including the development of other life-threatening conditions such as cancer. To date, no real-world study has assessed how incident cancer can affect adherence to concomitant pharmacotherapy and whether concomitant pharmacotherapy can minimize the negative effects of some cancer treatments on CAD-related morbidity and expenditures among individuals with CAD and incident cancer. To fill the knowledge gap, the three related aims of this dissertation were to analyze: 1) the association between incident breast, colorectal, and prostate cancer diagnosis and adherence to statins and/or ACEIs/ARBs/beta-blockers among elderly fee-for-service (FFS) Medicare beneficiaries with pre-existing CAD; 2) the impact of non-adherence to these medication classes on short-term CAD-related hospitalizations in patients with incident cancer diagnosis; and 3) the impact of incident cancer diagnosis on short-term CAD-related inpatient and outpatient healthcare expenditures. The study used a retrospective observational longitudinal cohort study design was conducted among elderly Medicare FFS beneficiaries with pre-existing CAD and those with incident breast cancer (BC), colorectal cancer (CC), or prostate cancer (PC), using multiple years (2005--2012). The study data was derived from the cancer registry data from Surveillance, Epidemiology and End Results (SEER) program linked with the Medicare claims data, the American community survey census-tract files and Area Health Resource Files. Aim 1 and Aim 3 also included 5% non-cancer random sample of Medicare beneficiaries, residing in SEER regions, with pre-existing CAD. Each individual was observed for 48 months with 24-month baseline (for identification of CAD and baseline characteristics) period, 12-month pre-index, and 12-month post-index periods. In the first aim, only 28.9% of the elderly with CAD were adherent to both statins and ACEIs/ARBs/beta-blockers. In the adjusted analyses, women [AOR = 0.70; 95% CI = 0.58, 0.81; P \u3c 0.0001] and men [AOR = 0.63; 95% CI = 0.51, 0.75; P \u3c 0.0001] with CC and men with PC [AOR = 0.92; 95% CI = 0.85, 0.99; P = 0.022] were significantly less likely to be adherent to both medication classes compared to women and men with NC, respectively. No significant differences in adherence to medications were observed among women with BC compared to women with NC. Even among those using single medication class, women [AOR = 0.64; 95% CI = 0.50, 0.79; P \u3c 0.0001] and men with CC [AOR = 0.59; 95% CI = 0.42, 0.76; P \u3c 0.0001] were significantly less likely to be adherent to that medication class compared to women and men with NC. In the second aim, adherence to both statins and ACEIs/ARBs/beta-blockers was estimated at 31.2% during the 120-day period immediately after cancer diagnosis; 13.7% were not adherent to both medication classes during the same period; 27.4% had CAD-related hospitalizations immediately after cancer diagnosis and this percentage declined to 10.6% during the last four months of the post-cancer period. In the adjusted analyses, those not adherent to both statins and ACEIs/ARBs/beta-blockers were more likely to have CAD-related hospitalization compared to those who were adherent to both medication classes [AOR = 1.82; 95% CI = 1.72, 1.92; P \u3c 0.0001]. In the third aim, overall, CAD-related mean healthcare expenditures at pre-index period accounted for about 32.6%--39.5% of total expenditures among women and 41.5% - 46.8% among men. In the adjusted GLMM, all cancer groups had significantly higher CAD-related healthcare expenditures compared to the non-cancer groups. Women with CC 153% higher expenditures compared to women with no cancer [beta = 0.93, P \u3c 0.0001]. Men with CC had 166% higher expenditures compared to men with NC [beta = 0.98, P \u3c 0.0001]. Further, men and women with CC had 57% and 55% higher expenditures compared to men with PC and women with BC, respectively. In summary, the study findings, collectively, suggest that cancer diagnosis negatively impacts adherence to CAD pharmacotherapy. Reduction in adherence was associated with increase in CAD-related hospitalizations and subsequent increase in CAD-related expenditures. This warrants the integration of cardiovascular care in the elderly diagnosed with cancer. Future studies need to explore whether the emerging collaborative care models, such as medical homes, can reduce inpatient use, and consequently, CAD-related expenditures

Design and Synthesis of CDK-5 and MEK-5 Inhibitors and Synthesis towards Tubulysin Analogs

CDK-5 is associated with hyperphosphorylation of the microtubule-associated protein tau, formation of neurofibrillary tangles, and possibly an acceleration of the neurodegenerative progression of Alzheimer\u27s disease. C6-O linked benzimidazoles and C-4 benzamide and phenylacetamide benzimidazoles based on (R)-Roscovitine, a non-selective inhibitor of CDK-5 were designed and synthesized. MEK-5, a member of the MAPK family, phosphorylates ERK-5 permitting cells to survive oxidative stress. MEK-5 is upregulated in tumor cells and activated by mitogens; inhibition of this enzyme is a potential anti-cancer strategy. Scaffolds from the following classes--benzimidazole, diphenylamine, flavones, and ortho-carboxyamide were examined for their capacity to be developed into potent and selective MEK-5 inhibitors. Tubulysin is a natural product that disrupts microtubule dynamics, blocks mitosis, and induces cell death. It has been examined as a potential anti-cancer agent in hollow fiber assays. Simple and reliable procedures were developed for the gram-scale synthesis of Mep-Ile dipeptide and Tup fragments of tubulysin

The Multifunctional Roles of Polyphenols in Plant-Herbivore Interactions

There is no argument to the fact that insect herbivores cause significant losses to plant productivity in both natural and agricultural ecosystems. To counter this continuous onslaught, plants have evolved a suite of direct and indirect, constitutive and induced, chemical and physical defenses, and secondary metabolites are a key group that facilitates these defenses. Polyphenols—widely distributed in flowering plants—are the major group of such biologically active secondary metabolites. Recent advances in analytical chemistry and metabolomics have provided an opportunity to dig deep into extraction and quantification of plant-based natural products with insecticidal/insect deterrent activity, a potential sustainable pest management strategy. However, we currently lack an updated review of their multifunctional roles in insect-plant interactions, especially focusing on their insect deterrent or antifeedant properties. This review focuses on the role of polyphenols in plant-insect interactions and plant defenses including their structure, induction, regulation, and their anti-feeding and toxicity effects. Details on mechanisms underlying these interactions and localization of these compounds are discussed in the context of insect-plant interactions, current findings, and potential avenues for future research in this area

Desktop scanning electron microscopy in plant-insect interactions research: A fast and effective way to capture electron micrographs with minimal sample preparation

The ability to visualize cell and tissue morphology at a high magnification using scanning electron microscopy (SEM) has revolutionized plant sciences research. In plant-insect interactions studies, SEM based imaging has been of immense assistance to understand plant surface morphology including trichomes (plant hairs; physical defense structures against herbivores (Kaur and Kariyat, 2020a, 2020b; Watts and Kariyat, 2021), spines, waxes, and insect morphological characteristics such as mouth parts, antennae, and legs, that they interact with. While SEM provides finer details of samples, and the imaging process is simpler now with advanced image acquisition and processing, sample preparation methodology has lagged. The need to undergo elaborate sample preparation with cryogenic freezing, multiple alcohol washes and sputter coating makes SEM imaging expensive, time consuming, and warrants skilled professionals, making it inaccessible to majority of scientists. Here, using a desktop version of Scanning Electron Microscope (SNE- 4500 Plus Tabletop), we show that the “plug and play” method can efficiently produce SEM images with sufficient details for most morphological studies in plant-insect interactions. We used leaf trichomes of Solanum genus as our primary model, and oviposition by tobacco hornworm (Manduca sexta; Lepidoptera: Sphingidae) and fall armyworm (Spodoptera frugiperda; Lepidoptera: Noctuidae), and leaf surface wax imaging as additional examples to show the effectiveness of this instrument and present a detailed methodology to produce the best results with this instrument. While traditional sample preparation can still produce better resolved images with less distortion, we show that even at a higher magnification, the desktop SEM can deliver quality images. Overall, this study provides detailed methodology with a simpler “no sample preparation” technique for scanning fresh biological samples without the use of any additional chemicals and machinery

Sex and stress modulate pupal defense response in tobacco hornworm

In insects, larval and adult defenses against predators have been well studied. However, pupal (also known as resting stage) defenses have been overlooked and not examined thoroughly. Although some pupa possess antipredator strategies such as hairs, spines, cryptic coloration, and exudation of chemicals, few studies have tested these responses and the factors affecting them. Here, we investigated the behavioral responses in tobacco hornworm Manduca sexta that pupates in soil by introducing an external stimulus using vibrations from an electric toothbrush to mimic predation. We observed that M. sexta made violent wriggling (twitching), followed by pulsating movements in response to the vibrational stimulus. Detailed examination showed that these twitches and pulsating events occurred more frequently and for longer periods of time in male pupa and were dependent on the magnitude of the stress (high and low frequency). However, when we estimated the angular force exerted by pupa using radian and angular momentum of twitches, it was found to be independent of pupal sex. A follow-up experiment on possible cascading effects of stress exposure on eclosion success revealed that low- and high-frequency stress exposure didn’t cause any of the common defects in eclosed adults. Our study clearly demonstrates that the so-called defenseless pupal stage uses a wide range of measurable defense behaviors that can actively defend against predators and should be examined further-linking observed behavior with underlying mechanisms

Trichomes mediate plant–herbivore interactions in two Cucurbitaceae species through pre- and post-ingestive ways

Plant structural defenses such as trichomes exert a significant selection pressure on insect herbivores. However, whether variation in structural defense traits affects common herbivores in related plant species is less understood. Here, we examined the role of trichomes in plant–herbivore interactions in two commonly cultivated members in Cucurbitaceae: bottle gourd (Lagenaria siceraria) and cucumber (Cucumis sativa). In common garden experiments when the two species were grown together, we observed that they differed in their attractiveness to four major herbivore species (Trichoplusia ni, Acalymma vittatum, Diaphania indica, and Anasa tristis) and, consequently, their feeding behavior. We found that L. siceraria consistently harbored less herbivores, and the two lepidopteran herbivores (T. ni and D. indica) were found to take significantly longer time to commence feeding on them, a primary mode of pre-ingestive defense function of trichomes. To tease apart structural and chemical modes of defenses, we first used scanning electron microscopy to identify, quantify, and measure trichome traits including their morphology and density. We found that C. sativa has significantly lower number of trichomes compared to L. siceraria, regardless of trichome type and leaf surface. We then used artificial diet enriched with trichomes as caterpillar food and found that trichomes from these two species differentially affected growth and development of T. ni showing cascading effects of trichomes. Taken together, we show that trichomes, independent of chemical defenses, are an effective pre- and post-ingestive defense strategy against herbivores with negative consequences for their feeding, growth, and development

The Multifunctional Roles of Polyphenols in Plant-Herbivore Interactions

There is no argument to the fact that insect herbivores cause significant losses to plant productivity in both natural and agricultural ecosystems. To counter this continuous onslaught, plants have evolved a suite of direct and indirect, constitutive and induced, chemical and physical defenses, and secondary metabolites are a key group that facilitates these defenses. Polyphenols—widely distributed in flowering plants—are the major group of such biologically active secondary metabolites. Recent advances in analytical chemistry and metabolomics have provided an opportunity to dig deep into extraction and quantification of plant-based natural products with insecticidal/insect deterrent activity, a potential sustainable pest management strategy. However, we currently lack an updated review of their multifunctional roles in insect-plant interactions, especially focusing on their insect deterrent or antifeedant properties. This review focuses on the role of polyphenols in plant-insect interactions and plant defenses including their structure, induction, regulation, and their anti-feeding and toxicity effects. Details on mechanisms underlying these interactions and localization of these compounds are discussed in the context of insect-plant interactions, current findings, and potential avenues for future research in this area

Revisiting the Genomic Approaches in the Cereals and the Path Forward

The important difficulties confronting humanity in the current era include combating global climate change, meeting human nutritional demands, and ensuring adequate energy sources. Cereal crops, which are grasses cultivated for their edible grains, are the primary dietary energy sources for humans and livestock and are produced in greater quantities than any other crop types. This chapter discusses the advancement and potential of various genomic tools for five main kinds of cereal: rice, maize, wheat, barley, and sorghum. We have discussed and speculated the advancements of genomics in plant improvement varying from transgenic cultivars, molecular markers and next-generation sequencing, linkage and association mapping, genome editing, pan-genome and super pan-genome sequencing, haplotype and optimal contribution selection, genomic and phenomics-assisted breeding, and finally merger of the domain of data science with plant genomics and breeding. The main success of each of these genomic tools is discussed for each crop, and why certain of them failed for specific crops is discussed with potential aspects to strengthen them with new tools. The chapter is divided into two sections. First, we have covered the traditionally used genomics. The other half shows the potential of novel genomic tools with the integration of data science. This chapter allows the reader to learn from the past inventions and failures to implement the new genomic tools with high precision and efficacy

Surface Warfare: Plant Structural Defenses Challenge Caterpillar Feeding

Herbivorous insects, especially caterpillars, exert significant selection pressure on their host plants, as they exclusively depend on them for their growth and development. To counter this extensive loss of plant biomass that significantly affects their growth, development, and fitness, plants have evolved a suite of structural and chemical defenses. Structural defenses, including surface waxes and trichomes, are primarily present at the leaf surface where caterpillars tend to initiate their feeding after hatching. In this chapter, we argue that these structural defenses play an equally important role to their counterpart, chemical defenses, which have traditionally received disproportionately more attention. We discuss various roles played by waxes and trichomes as examples of surface structural defenses, their chemical composition, and morphological features that assist in combating herbivory in various caterpillar-host plant systems. We then use trichomes as a model to discuss the specificity and diversity of plant-herbivore interactions and to examine the counter defense strategies employed by caterpillars to thwart these defenses. Finally, we discuss current developments and future avenues bridging natural history and mechanistic underpinnings in our understanding of structural defenses and their ongoing surface war against caterpillars