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Evolution of defense against herbivores in plants: an optimal allocation model and field study

Goal: We study the cost of different sexual forms of Opuntia robusta and differences in their extent of defense against herbivores.

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Project log

Hector León-Solano
added 4 research items
The relationship between relative air humidity and air temperature (A) or sampling time (B), and between air temperature and sampling time (C). (PDF)
The Optimal Defense Hypothesis (ODH) predicts that younger, more valuable plant organs should be better defended. We tested this hypothesis in Opuntia robusta Wendl. since its sequential, hierarchical and segmented architecture permits the consideration of a possible reallocation of secondary metabolites among cladodes with different age. We performed a field study taking samples of vegetative tissues from cladodes of different orders during eight months, and a field experiment, by covering either apical or basal cladodes with a fabric. We determined the content of 4-hydroxybenzoic acid (4-HBA), chlorogenic acid (CGA), quercetin (QUE) and salicylic acid (SA). 4-HBA and CGA followed the predictions of ODH. QUE followed an inverse tendency. SA did not show any tendency related either with the position of the cladode or the treatment (light vs. shade) however, its concentration was positively correlated with the concentration of 4-HBA. As we detected SA only in a low proportion of cladodes and 4-HBA in all cladodes, we hypothesize the conversion of the latter metabolite to the former one. Contrary to ODH, CGA presented lower concentrations in apical than in basal cladodes when co-occurred with SAL, and QUE was transferred from apical (younger) to basal (older) cladodes. In this study, we found contradictions in the premises and outcomes of both the Resource Availability Hypothesis (RAH) and the ODH, suggesting that a new hypothesis concerning the plant defense against stress factors should be proposed.
Mariusz Janczur
added a research item
The optimal defence hypothesis predicts that increased plant defence capabilities, lower levels of damage, and lower investment in vegetative biomass will occur more frequently in sexual forms with higher resource-demanding tissue production and/or younger plant parts. We aimed to examine the effects of sexual form, cladode, and flower age on growth rate, herbivore damage, and 4-hydroxybenzoic acid (4-HBA), chlorogenic acid, and quercetin (QUE) concentrations in Opuntia robusta plants in central Mexico. Our findings demonstrated that hermaphrodite flowers showed faster growth and lesser damage than female flowers. The effect of cladode sexual forms on 4-HBA and QUE occurrence was consistent with the predictions of the optimal defence hypothesis. However, chlorogenic acid occurrences were not significantly affected by sexual forms. Old cladodes exhibited higher QUE and 4-HBA occurrences than young cladodes, and hermaphrodites exhibited higher 4-HBA concentrations than females. Resource allocation for reproduction and secondary metabolite production, and growth was higher and lower, respectively, in females, compared to hermaphrodites, indicating a trade-off between investment in reproduction, growth, and secondary metabolite production. Secondary metabolite concentrations in O. robusta plants were not negatively correlated with herbivore damage, and the two traits were not accurate predictors of plant reproductive output.
Hilda Araceli Zavaleta-Mancera
added a research item
The anatomical aspects of vascularization and distribution of starch during the morphogenesis of the floral bud are unknown for Prunus persica (L.), and this knowledge helps to predict the degree of vascularization and susceptibility of the bud to cold temperatures. The aim of the present study was to compare the differentiation of the xylem and the distribution of starch in flower buds, from the phenological stage (PS) “dormancy” to “visible stamens” in the Puebla, CP Precoz and Zacatecas cultivars (early, intermediate and late flowering). Sampling was carried out completely at random (two flower buds of the middle part of five mixed twigs (one year old), from 10 trees (per cultivar) from October 29th (autumn) to March 19th (winter), 2012. The tissues were fixed in a formaldehyde -alcohol-water (FAA) solution, and processed in Paraplast. Serial sections were stained using Safranin O and Fast green FCF. The anatomical changes observed were consistent for each PS studied, regardless of the cultivar and flowering date. At the start of the PS “dormancy” there was no vascular connection between the pedicel and the ovary. In the PS “swollen bud,” the xylem reached the base of the ovary and starch was found in the ovary and anthers. In the PS “buds with visible calyx,” the xylem reached the stigma and the starch remained in the ovary and anthers. In the PS “pink tip,” the anther matured and presented no starch. In the PS “visible stamens,” the stigma and the ovule matured and starch was almost absent. The presence of starch preceded the differentiation of the xylem. The vascularization in the vegetative whorls was delayed in the intermediate and late cultivars, in contrast with the early cultivar.
Hilda Araceli Zavaleta-Mancera
added an update
PLANT CELL STRUCTURE AN SENESCENCE
 
Hilda Araceli Zavaleta-Mancera
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PLANT CELL ULTRASTRUCTURE AND SENESCENCE
 
Hilda Araceli Zavaleta-Mancera
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CELL BIOLOGY OF PLANT SENESCENCE
 
Mario A. Sandoval-Molina
added 2 research items
Ants’ activity on cladode sprouts. Ants searched mainly the apical secretory cones of young spines in areoles. We observed the secretion of transparent liquid, which attracted and fed ants. (MP4)
The number of ants observed on sprouts with a given size (length, width, thickness), together with air temperature and humidity recorded at the moment of sampling. (XLSX)
Hilda Araceli Zavaleta-Mancera
added a research item
Estudio de la identificacion y caracterización de los agroecosistemas donde se producen algunas especies del genero Vainilla en la region del Totonacapan México
Mariusz Janczur
added 3 research items
To our knowledge, there are no studies about the structure and ecological function of extrafloral nectaries (EFNs) in Opuntia robusta. This is the first description of EFNs in O. robusta, where young spines have an interesting structure and a secreting function, which are different from EFNs described in other Cactaceae species. We used light, scanning-electron, and transmission-electron microscopy to examine morphology, anatomy, and ultrastructure of the secretory spines in areoles in female and hermaphrodite individuals of O. robusta. Young cladodes develop areoles with modified and secretory spines as EFNs only active during the early growth phase. EFNs are non-vascularized structures, with no stomata, that consist of a basal meristematic tissue, a middle elongation region, and an apical secretory cone formed by large globular epidermal cells, containing nectar and medullar elongated cells. We observed the presence of Golgi apparatus, vesicles and plastids in the medullar and sup-epidermal cells of the spine. We propose that the nectar is stored in the globular cells at the apex of the spine and secreted by breaking through the globular cells or by pores. We recorded a more frequent presence of ants on younger cladode sprouts producing young secreting spines: this result is parallel with the predictions of Optimal Defense Hypothesis, which states that younger plant organs should be better defended than older ones because their loss produces a higher fitness impairment. Although Diaz-Castelazo’s hypothesis states that a more complex structure of EFNs correlates with their lower among-organs dispersion, comparing to less complex EFNs, non-vascularized structure of EFNs in O. robusta is not associated with their higher among-organs dispersion likened to O. stricta, which produces vascularized EFNs. We provide evidence that this characteristic is not a good taxonomic feature of Opuntia genus. Moreover, the comparison of EFNs of O. robusta and O. stricta suggests that the hypothesis of Diaz-Castelazo should be revised: it is rather a rule but not a law.
Mariusz Janczur
added a research item
To our knowledge, there are no studies about the structure and ecological function of extra- floral nectaries (EFNs) in Opuntia robusta. This is the first description of EFNs in O. robusta, where young spines have an interesting structure and a secreting function, which are differ- ent from EFNs described in other Cactaceae species. We used light, scanning-electron, and transmission-electron microscopy to examine morphology, anatomy, and ultrastructure of the secretory spines in areoles in female and hermaphrodite individuals of O. robusta. Young cladodes develop areoles with modified and secretory spines as EFNs only active during the early growth phase. EFNs are non-vascularized structures, with no stomata, that consist of a basal meristematic tissue, a middle elongation region, and an apical secretory cone formed by large globular epidermal cells, containing nectar and medullar elongated cells. We observed the presence of Golgi apparatus, vesicles and plastids in the medullar and sup-epidermal cells of the spine. We propose that the nectar is stored in the globular cells at the apex of the spine and secreted by breaking through the globular cells or by pores. We recorded a more frequent presence of ants on younger cladode sprouts producing young secreting spines: this result is parallel with the predictions of Optimal Defense Hypothesis, which states that younger plant organs should be better defended than older ones because their loss produces a higher fitness impairment. Although Diaz-Castelazo’s hypothesis states that a more complex structure of EFNs correlates with their lower among-organs dispersion, comparing to less complex EFNs, non-vascularized structure of EFNs in O. robusta is not associated with their higher among-organs dispersion likened to O. stricta, which produces vascularized EFNs. We provide evidence that this characteristic is not a good taxonomic fea- ture of Opuntia genus. Moreover, the comparison of EFNs of O. robusta and O. stricta sug- gests that the hypothesis of Diaz-Castelazo should be revised: it is rather a rule but not a law.
Hector León-Solano
added 2 research items
Sexually dimorphic plants provide an excellent opportunity for examining the differences in the extent of their defense against herbivores because they exhibit sex-related differences in reproductive investment. Such differences enable comparison of the sex with high reproduction expenses with the sex that expends less. The more costly sex is usually also better defended against herbivores. Generally, females are considered more valuable than hermaphrodites in terms of fitness; however, hermaphrodites are more valuable if they can produce seed by autonomous selfing, provided that the inbreeding depression is low and pollen is limited. We studied a gynodioecious population of Opuntia robusta from Central-Eastern Mexico, which has been reported to be trioecious, dioecious, or hermaphrodite, and addressed the following questions: 1) Is the hermaphrodite's reproductive output higher than the female's, and are hermaphrodites thus better defended? 2) Are plant tissues differentially defended? 3) Do trade-offs exist among different physical defense traits? and 4) among physical and chemical defense traits? We found that 1) hermaphrodites had a higher seed output and more spines per areola than females and that their spines contained less moisture. Non-reproductive hermaphrodite cladodes contained more total phenolic compounds (TPCs) than female ones. In addition, 2) hermaphrodite reproductive cladodes bore more spines than female cladodes, and 3) and 4) we found a negative relationship between spine number per areola and areola number per cladode and a positive relationship between spine number per areola per plant and TPC concentration per plant. Non-reproductive hermaphrodite cladodes contained a higher concentration of TPCs than female cladodes, and parental cladodes contained fewer TPCs than both reproductive and empty cladodes.
We surveyed of 50 individuals of Heliconia uxpanapensis C. Gut. Báez, an understory herb common in the forest and trail sides of Los Tuxtlas Biological Station, a tropical rainforest. In these plants we found the presence of beetles of the genus Chelobasis in the Sierra de Los Tuxtlas, being the first record of the genus for Mexico. Los Tuxtlas is the northern limit of the tropical rainforest in the Americas and may be the northern limit for Ch. Bicolor. Thus, the new record expands the known latitudinal range of the genus Chelobasis by ca. 450 km to the north.
Mariusz Janczur
added a research item
During our previous study (Janczur et al. 2014), we saw adult Euphoria inside the flowers of Opuntia robusta (Wendland) (Fig. 1A) and Opuntia spinulifera (Scheinvar) (Fig. 1B). To ensure a correct identification, we collected one male and two females in San Nicolás Tecoaco, municipality of Singuilucan, Hidalgo on 15 April 2014. These were identified as E. basalis by using the key in Orozco (2012). The specimens are deposited in the collection of Laboratorio de Investigación y Análisis, Entomological Research, Metepec, Estado de México. After consulting the literature, we concluded that, to the best of our knowledge, this is the first time E. basalis is reported to feed on flowers of the genus Opuntia. Additionally, this is the first time the species was observed in April, since generally it is more abundant from July through September.
Hilda Araceli Zavaleta-Mancera
added an update
FITOTOXICIDAD DE NANOPARTICULAS METALICAS
 
Hilda Araceli Zavaleta-Mancera
added an update
Fitotoxicidad de nanopartículas metalicas
 
Mariusz Janczur
added a research item
During our previous study), we saw adult Euphoria inside the flowers of Opuntia robusta (Wendland) and Opuntia spinulifera (Scheinvar). To ensure a correct identification, we collected one male and two females in San Nicolás Tecoaco, municipality of Singuilucan, Hidalgo on 15 April 2014. These were identified as E. basalis. After consulting the literature, we concluded that, to the best of our knowledge, this is the first time E. basalis is reported to feed on flowers of the genus Opuntia. Additionally, this is the first time the species was observed in April, since generally it is more abundant from July through September.
Mariusz Janczur
added a project goal
We study the cost of different sexual forms of Opuntia robusta and differences in their extent of defense against herbivores.