Significance: Are there biological constants unifying phenotypic diversity across scales? Metabolic scaling theory (MST) predicts mathematical regularity and constancy in the allometric scaling of growth rate with body size across species. Here we show that adaptation to climate inArabidopsis thalianais associated with local strains that substantially deviate from the values predicted by MST. This deviation can be linked to increased stress tolerance at the expense of seed production, and it occurs through selection on genes that are involved in the abiotic stress response and are geographically correlated with climatic conditions. This highlights the evolutionary role of allometric diversification and helps establish the physiological bases of plant adaptation to contrasting environments.

Life history strategies of most organisms are constrained by resource allocation patterns that follow a ‘slow-fast continuum’. It opposes slow growing and long-lived organisms with late investment in reproduction to those that grow faster, have earlier and larger reproductive effort and a short longevity. In plants, the Leaf Economics Spectrum (LES) depicts a leaf-level trade-off between the rate of carbon assimilation and leaf lifespan, as stressed in functional ecology from interspecific comparative studies. However, it is still unclear how the LES is connected to the slow-fast syndrome. Interspecific comparisons also impede a deep exploration of the linkage between LES variation and adaptation to climate. Here, we measured growth, morpho-physiological and life-history traits, at both the leaf and whole-plant levels, in 378 natural accessions of Arabidopsis thaliana. We found that the LES is tightly linked to variation in whole-plant functioning, and aligns with the slow-fast continuum. A genetic analysis further suggested that phenotypic differentiation results from the selection of different slow-fast strategies in contrasted climates. Slow growing and long-lived plants were preferentially found in cold and arid habitats while fast growing and short-lived ones in more favorable habitats. Our findings shed light on the role of the slow-fast continuum for plant adaptation to climate. More broadly, they encourage future studies to bridge functional ecology, genetics and evolutionary biology to improve our understanding of plant adaptation to environmental changes.

In this study, we investigated how increasing temperature affects tomato fruit physicochemical traits and looked for genetic variability to help maintain fruit quality in the context of climate change. High temperature (HT: +3 °C) was applied at four fruit developmental stages, from anthesis and 15, 30 or 45 days after anthesis until ripening to three genotypes, a commercial cultivar (Money Maker, “MM”) and two genotypes likely more tolerant to HT (Campeche 40 “C40”, a landrace from a warm, humid region, and a hybrid Chapingo F1, “F1”, resulting from crossbreeding landraces tolerant to high temperature). Increasing average diurnal temperature (from 27.0 to 29.9) reduced fruit firmness and size and affected fruit composition according to genotype. Sugar and acid contents were highly impacted in MM and C40 fruits, especially when HT was applied during the rapid fruit growth period. The application of HT at different fruit developmental stages revealed that HT could enhance acid accumulation and degradation (rate and/or duration), resulting in different effects on fruit acidity between genotypes. The F1 genotype appeared to be more adapted to HT, producing larger fruits with higher sugar, lower acid and increased vitamin C and calcium content. These results provide interesting directions for breeding programs that want to maintain future tomato fruit yields and quality.

La producción y distribución de semillas mejoradas son el puente de transferencia de tecnología entre fitomejoradores y productores, para alcanzar niveles competitivos en la producción. Sin embargo, en México las semillas mejoradas de maíz (Zea mays L.) se siembran en sólo 30 % de la superficie ocupada por este cultivo. En esta investigación se estudió el mercado nacional de semillas y se analizó la posibilidad de desarrollo de pequeñas empresas productoras de semilla de maíz. Con la Ley de Producción, Certificación y Comercio de Semillas (LPCCS) de 1961 se permitió al Estado Mexicano promover la generación de variedades y la producción y comercio de semillas. En 1989 se produjeron 350 mil toneladas de semilla, de las cuales 28 mil fueron de maíz. En 1991 se promulgó una nueva LPCCS que permitió la participación sin restricciones del sector privado en la investigación, producción y comercialización de semilla, y también se restringió al sector público al grado de que la Productora Nacional de Semillas fue liquidada. Esto originó una fuerte caída en la producción de semillas (163 mil toneladas en 1995, de las cuales 15 mil fueron de maíz) y la expansión masiva de megaempresas transnacionales en la industria semillera nacional, que han consolidado un oligopolio. En 2009 se sembraron en México 8 millones de hectáreas de maíz, de las cuales 1.5 millones fueron con 45 mil toneladas de semilla híbrida. De éstas, 95 % fueron producidas por Monsanto y Pioneer principalmente, y el resto (3 mil toneladas) por pequeñas empresas. Aquí se propone promover la participación de pequeñas empresas productoras de semilla de maíz a escala local y regional, que atiendan a productores que siembran superficies reducidas en regiones agroecológicas especiales, lo cual ampliaría la superficie sembrada con semilla mejorada. Esta acción se debe articular con una dinámica agrícola (cadena de valor) que genere nuevas variedades y atienda la producción, distribución, asesoría técnica y comercialización del maíz.

In México, 44 thousand hectares are planted with tomatillo or husk tomato (Physalis philadelphica Lam.), which occupies fourth place among the country's vegetable species. However, research on this species is scarce, especially that related to the process of seed deterioration. We studied the effects of deterioration in tomatillo seed, var. CHF1-Chapingo, stored from 2-mo up to 7 yr with no climate control, 18.2 ± 5 °C and 41 ± 10% relative humidity, on physiological and biochemical variables during germination. It was found that germination, vigor, and respiratory activity decrease significantly from the first year of storage; thus, after 7 yr, germination and vigor decreased 99%, and respiratory activity of seed after 48 h imbibition decreased 78%. Linoleic acid (unsaturated) content correlated positively with germination (R = 0.78**) and with speed of radicle emergence (R = 0.79**). Germination correlated with speed of radicle emergence (R = 0.99**) and with respiratory activity after 48 h of imbibition (R = 0.79**). Both respiratory activity and fatty acid content are involved in natural deterioration of tomatillo seed

This study was conducted to evaluate the influence of fruit maturity and postharvest storage on the physiological qualities of chili seeds during development. Two types of chili were used (ancho and guajillo). Fruits were harvested at 40, 60, 80, 100, 120 and 140 days after anthesis (daa) and stored for 0, 7 and 14 days after harvest (dah). The moisture content of guajillo seeds throughout development decreased from 86 to 17%, while ancho maintained moisture at 47% at 80 dda. It was confirmed that precocious harvest (40 daa) was not beneficial to the physiological quality of chili seeds, even when it was associated with 14 dah. Germinability was correlated with electrical conductivity (R = −0.76): Ancho seeds germinated starting from 472.5 μS·cm−1·g−1 and guajillo seeds from 679.3 μS·cm−1·g−1. In fruits harvested 80 daa, 14 dah was essential to ensure the physiological quality of seeds in both types of chilies: mean germination was above 93%, and seed vigor was higher (germination after accelerated aging and mean germination speed were more than 90% and 5.6 radicle d−1, respectively). Seeds harvested 120 daa were of high quality, and post-harvest storage of fruits was not necessary. Expression of two late embryogenesis abundant (LEA) proteins was detected in both types of chilies: the first synthesis (65 kDa) occurred 80 daa, and the second (50 kDa) occurred 120 daa and this was directly related to the maximal physiological quality of chili seeds.