.

Arbre toujours au milieu
De tout ce qui l'entoure
Arbre qui savoure
La voûte des cieux

Rainer Maria Rilke 

.

 

Richard Feynman - Ode To A Flower from Cub Studio on Vimeo.

 

 .

Sesou

 

Apenas un adolescente, entre confundido y asustado llegué a la pequeña comunidad. Sin avisar armé mi carpa amarrillo chillón en algún sitio no bien pensado. Todavía con el entendimiento entumecido por el susto de la aventura y mientras ordenaba las pocas cosas que traía, sentí algo y volteé… para mi sorpresa, dentro de mi carpa y justo detrás de mí se encontraba un viejo indígena sentado en cuclillas. Recuerdo perfectamente la impresión que me causó la profundad de las arrugas de su rostro.

-No trajiste regalito- me preguntó. Le entregué un chocolate sin decir palabra y el igualmente se fue. Así conocí a Sesou.

Con el tiempo trabé amistad con los niños de la comunidad y después con Iona Romero, la madre de un buen número de ellos.Una amistad para toda la vida. En algún momento Iona me convenció de ir a una celebración en una comunidad cercana. Al solo llegar, vi una larga fila de indígenas que ordenadamente esperaban ser bautizados en un río por un pastor, también indígena. Junto a Wida -hija de Iona- vagabundeé al azar entre las casas de la comunidad. Al rato nos acercamos a un grupo de personas que de pie se reunían en torno a alguien. Como pudimos nos colamos y para mi sorpresa vi a Sesou, quien con un gigantesco pedazo de carne asada en la mano, gritaba agresivamente a los demás. Traté que Wida me tradujera lo que decía, pero no quiso.

 -Ese es un viejo loco - me dijo- el cree que es dueño de la sabana.

Mucho tiempo después, Sesou se me acercó mientras yo holgazaneaba acostado sobre una roca.

 –¿Quieres ayudar en el Conuco?- dijo y yo inmediatamente me levanté dispuesto a poner manos a la obra. Él se extrañó y se fue sin decir más. Solo después de trascurrida una semana y media partimos caminando a su lejano Conuco. Así, aprendí que hay otras formas de entender lo inmediato y de relacionarse con tiempo.

Pasamos todo el día trabajando, yo haciendo torpemente lo que Sesou me indicaba. Al inicio de la tarde paramos un rato a comer casabe con picante, le comenté que había visto algunos gusanos comiéndose las hojas los cultivos y le dije que si quería podía matarlos.

 –Hay suficiente para ellos y para nosotros, todos nos beneficiamos- dijo Sesou.

También me ofrecí a apilar en un rincón los restos de troncos quemados que desordenadamente se encontraban dispersos en el conuco. Tampoco aceptó, yo simplemente pensé que era un indio terco. Al poco tiempo volvimos a trabajar, duro, muy duro hasta el atardecer. Después, de noche, acostados en chinchorros a la luz de las brasas, tuve el privilegio de escuchar, por primera vez en mi vida, el relato de cómo –en el pasado mítico- Makunaima derribó el Árbol de la Vida.

En varias ocasiones regresé a visitar a la familia Romero, a Iona y sus muchachos. Pregunté por el viejo Sesou, nadie parecía estar seguro.

 - Murió hace mucho - me dijeron algunos, según otros desapareció en la sabana. Para mí fue una persona fundamental, por el decidí estudiar agricultura en la universidad. Sin embargo, ahí, ni una vez me hablaron del Conuco.

Después de graduado, un compañero de trabajo me habló maravillado de unos antiquísimos suelos amazónicos extremadamente fértiles, llamados Terra Preta do Indio, que son, sin lugar a dudas el producto de la quema de árboles en la agricultura precolombina (Petersen, Neves y Heckenberger, 2001). No pude dejar de recordar al viejo, la tarde aquella de trabajo y los troncos dispersos en el conuco. Transcurrido mucho más tiempo aun, leyendo con gran sorpresa un artículo de enigmático título en donde se describía cómo la mordida de un gusano puede ayudar a aumentar las cosechas (Poveda, Gómez y Kessler, 2010), finalmente me di cuenta… comprendí cuánto no había comprendido, lo diferente de los mundos y lo sutil que puede ser el racismo.

Tomado de: Griffon, D. 2020. Conuco: fruto del árbol Kalivirnae. En: Dinámica multifuncional de la agricultura familiar. Alimentación, ecología y economía (Ramírez y Ocampo, eds.).  Colegio de Postgraduados - Universidad de Guadalajara.

Libre aquí: https://bit.ly/2L1oBFP

 

.

 .

The Solstice

W.S. Merwin 

They say the sun will come back
at midnight
after all
my one love

but we know how the minutes
fly out into
the dark trees
and vanish

like the great ʻōhiʻas and honey creepers
and we know how the weeks
walk into the
shadows at midday

at the thought of the months I reach for your hand
it is not something
one is supposed
to say

we watch the bright birds in the morning
we hope for the quiet
daytime together
the year turns into air

but we are together in the whole night
with the sun still going away
and the year
coming back

.

Constraints on selfish behavior in plants      

Marina Semchenko, 2020

We are used to human behavior, and the actions of other animals, being described as selfish, aggressive, or cooperative. Such words come up less often when contemplating plants. Yet plants too have evolved a fascinating array of behavioral strategies in their struggle for resources, although these are hard to demonstrate and quantify.

Much of the world's plant biomass exists out of sight underground in the form of roots.  Plants adjust how and where their roots grow according to how close neighboring—and competing—plants might be. The model extracts some of the rules about how root balls differ when grown close to neighboring plants compared with being grown in the absence of competition.

Plant roots determine carbon uptake, survivorship, and agricultural yield and represent a large proportion of the world’s vegetation carbon pool. Study of belowground competition, unlike aboveground shoot competition, is hampered by our inability to observe roots. We developed a consumer-resource model based in game theory that predicts the root density spatial distribution of individual plants and tested the model predictions in a greenhouse experiment. Plants in the experiment reacted to neighbors as predicted by the model’s evolutionary stable equilibrium, by both overinvesting in nearby roots and reducing their root foraging range. We thereby provide a theoretical foundation for belowground allocation of carbon by vegetation that reconciles seemingly contradictory experimental results such as root segregation and the tragedy of the commons in plant roots.

DOI: 10.1126/science.abf2785 

DOI: 10.1126/science.aba9877 

Multilevel selection, population genetics and cooperation in structured populations

Jeremy Van Cleve

Ménage à Trois: Unraveling the Mechanisms Regulating Plant–Microbe–Arthropod Interactions      

Gruden et al., 2020.

Plant‐microbe‐arthropod (PMA) interactions have important impacts on plant fitness, and recent studies shed light on how plants regulate responses in such complex interactions.

Biosynthetic pathways for the production of defensive and signaling compounds, and the corresponding signaling modules (mostly related to phytohormones) are key regulators both in interactions of the plant with either microbes or arthropods (two-way interactions), or when exposed to both (PMA; three-way interactions).

Most signaling modules regulating two-way interactions of plants with microbes or arthropods also operate in three-way PMA interactions, but changes in their speed or intensity (e.g., defense priming) and/or activation of additional pathways frequently occur.

These differences shape the outcome of PMA interactions and may have implications for ecologically based crop protection. 

 

Illustration of Multiway Interactions between Plants, Microbes, and Arthropods (PMA) and the Main Signaling Pathways Orchestrating the Corresponding Plant Responses. Plants must fine-tune their molecular responses to the interaction with a plethora of organisms with different lifestyles. Microbes and arthropods interact and can alter each other’s effects on plant health through their modulation of plant responses. Continuous arrows represent the two-way interactions between the plant and the microbe or the arthropod. Discontinuous arrows represent the three-way PMA interactions. Major signaling pathways coordinating plant responses during two-way and PMA interactions are represented, namely volatile organic compounds (VOCs), jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), and ethylene signaling (ET). Major groups of arthropod and microbe lifestyles are illustrated by particular examples, microbes on the left side of the figure, arthropods on the right. The third trophic level (indirect interaction) is also represented by parasitoids and predators of arthropods. The insert represents arthropod-associated microbes impacting the arthropod interaction with the plant. Drawing by J. Lidoy, V. Lidoy, and J. Lidoy. Abbreviations: AM fungi, arbuscular mycorrhizal fungi; PGPF, plant growth-promoting fungi; PGPR, plant growth-promoting rhizobacteria.

 

https://doi.org/10.1016/j.tplants.2020.07.008

.  

 

 

Durable Resistance of Crops to Disease: A Darwinian Perspective

James K.M. Brown,  2015.

This review takes an evolutionary view of breeding crops for durable resistance to disease. An understanding of coevolution between hosts and parasites leads to predictors of potentially durable resistance, such as corresponding virulence having a high fitness cost to the pathogen or resistance being common in natural populations. High partial resistance can also promote durability. Whether or not resistance is actually durable, however, depends on ecological and epidemiological processes that stabilize genetic polymorphism, many of which are absent from intensive agriculture. There continues to be no biological, genetic, or economic model for durable resistance. The analogy between plant breeding and natural selection indicates that the basic requirements are genetic variation in potentially durable resistance, effective and consistent selection for resistance, and an efficient breeding process in which trials of disease resistance are integrated with other traits. Knowledge about genetics and mechanisms can support breeding for durable resistance once these fundamentals are in place.

 

Key features of host-parasite coevolution. (a) Reciprocal effects of interactions between host and parasite gene frequencies and fitnesses (Brown & Tellier 2011, Frank 1992, Tellier & Brown 2007). Center of diagram: A higher frequency of resistance increases the advantage of virulence, but increased virulence reduces the advantage of resistance. Top arrow: A greater cost of virulence reduces the frequency of virulence, thus increasing selection for resistance, which in turn restores the frequency of virulence. The net effect of a higher cost of virulence is to reduce the frequency of resistance. Bottom arrow: By similar logic, the net effect of a higher cost of resistance is to increase the frequency of virulence. (b) Unstable (red ) and stable (blue) polymorphisms in host and parasite gene frequencies. The unstable case is the model described in the sidebar A Simple Model of Host-Parasite Coevolution with parameters cost of resistance in host (u) = cost of virulence in parasite (b) = 0.05, cost to host of being diseased s = 0.24 and cost to parasite of incompatible interaction (c) = 1. The graph of gene frequencies spirals around and away from the unstable equilibrium point (red cross) at Req = 0.050, aeq = 0.833. The stable case has the same values of u, b, s, and c; two parasite generations per host generation; and mixed auto- and alloinfection with epidemiological parameters z = 1.4, ε = 0.1, and ϕ = 0.32 (128). The graph of gene frequencies spirals inward toward the stable equilibrium point (blue cross); the equilibrium frequency of resistance in the host is displaced slightly because of direct frequency-dependent selection on parasite. Models began with R = a = 0.02 and were run for 700 generations.

https://doi.org/10.1146/annurev-phyto-102313-045914