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Cellular regeneration in response to wounding is fundamental to maintain tissue integrity. Various internal factors including hormones and transcription factors mediate healing, but little is known about the role of external factors. To understand how the environment affects regeneration, we investigated the effects of temperature upon the horticulturally relevant process of plant grafting. We found that elevated temperatures accelerated vascular regeneration in Arabidopsis thaliana and tomato grafts. Leaves were crucial for this effect, as blocking auxin transport or mutating PHYTOCHROME INTERACTING FACTOR 4 (PIF4) or YUCCA2/5/8/9 in the cotyledons abolished the temperature enhancement. However, these perturbations did not affect grafting at ambient temperatures, and temperature enhancement of callus formation and tissue adhesion did not require PIF4, suggesting leaf-derived auxin specifically enhanced vascular regeneration in response to elevated temperatures. We also found that elevated temperatures accelerated the formation of inter-plant vascular connections between the parasitic plant Phtheirospermum japonicum and host Arabidopsis, and this effect required shoot-derived auxin from the parasite. Taken together, our results identify a pathway whereby local temperature perception mediates long distance auxin signaling to modify regeneration, grafting and parasitism. This article has an associated 'The people behind the papers' interview., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

Grafting is possible in both animals and plants. Although in animals the process requires surgery and is often associated with rejection of non-self, in plants grafting is widespread, and has been used since antiquity for crop improvement 1 . However, in the monocotyledons, which represent the second largest group of terrestrial plants and include many staple crops, the absence of vascular cambium is thought to preclude grafting 2 . Here we show that the embryonic hypocotyl allows intra- and inter-specific grafting in all three monocotyledon groups: the commelinids, lilioids and alismatids. We show functional graft unions through histology, application of exogenous fluorescent dyes, complementation assays for movement of endogenous hormones, and growth of plants to maturity. Expression profiling identifies genes that unify the molecular response associated with grafting in monocotyledons and dicotyledons, but also gene families that have not previously been associated with tissue union. Fusion of susceptible wheat scions to oat rootstocks confers resistance to the soil-borne pathogen Gaeumannomyces graminis. Collectively, these data overturn the consensus that monocotyledons cannot form graft unions, and identify the hypocotyl (mesocotyl in grasses) as a meristematic tissue that allows this process. We conclude that graft compatibility is a shared ability among seed-bearing plants., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Cell fate maintenance is an integral part of plant cell differentiation and the production of functional cells, tissues, and organs. Fleshy fruit development is characterized by the accumulation of water and solutes in the enlarging cells of parenchymatous tissues. In tomato ( Solanum lycopersicum ), this process is associated with endoreduplication in mesocarp cells. The mechanisms that preserve this developmental program, once initiated, remain unknown. We show here that analysis of a previously identified tomato ethyl methanesulfonate-induced mutant that exhibits abnormal mesocarp cell differentiation could help elucidate determinants of fruit cell fate maintenance. We identified and validated the causal locus through mapping-by-sequencing and gene editing, respectively, and performed metabolic, cellular, and transcriptomic analyses of the mutant phenotype. The data indicate that disruption of the SlGBP1 gene, encoding GUANYLATE BINDING PROTEIN1, induces early termination of endoreduplication followed by late divisions of polyploid mesocarp cells, which consequently acquire the characteristics of young proliferative cells. This study reveals a crucial role of plant GBPs in the control of cell cycle genes, and thus, in cell fate maintenance. We propose that SlGBP1 acts as an inhibitor of cell division, a function conserved with the human hGBP-1 protein., (© 2020 American Society of Plant Biologists. All rights reserved.)

Background and Aims: Since its emergence in the mid-20th century, invasion biology has matured into a productive research field addressing questions of fundamental and applied importance. Not only has the number of empirical studies increased through time, but also has the number of competing, overlapping and, in some cases, contradictory hypotheses about biological invasions. To make these contradictions and redundancies explicit, and to gain insight into the field's current theoretical structure, we developed and applied a Delphi approach to create a consensus network of 39 existing invasion hypotheses., Results: The resulting network was analysed with a link-clustering algorithm that revealed five concept clusters (resource availability, biotic interaction, propagule, trait and Darwin's clusters) representing complementary areas in the theory of invasion biology. The network also displays hypotheses that link two or more clusters, called connecting hypotheses , which are important in determining network structure. The network indicates hypotheses that are logically linked either positively (77 connections of support) or negatively (that is, they contradict each other; 6 connections)., Significance: The network visually synthesizes how invasion biology's predominant hypotheses are conceptually related to each other, and thus, reveals an emergent structure - a conceptual map - that can serve as a navigation tool for scholars, practitioners and students, both inside and outside of the field of invasion biology, and guide the development of a more coherent foundation of theory. Additionally, the outlined approach can be more widely applied to create a conceptual map for the larger fields of ecology and biogeography., (© 2020 The Authors. Global Ecology and Biogeography published by John Wiley & Sons Ltd.)

Intraspecific trait variability (ITV) maintains functional diversity in populations and communities, and plays a crucial role in ecological and evolutionary processes such as trophic cascades or speciation. Furthermore, functional variation within a species and its populations can help buffer against harmful environmental changes. Trait variability within species can be observed from differences among populations, and between- and within individuals. In animals, ITV can be driven by ontogeny, the environment in which populations live and by within-individual specialization or variation unrelated to growth. However, we still know little about the relative strength of these drivers in determining ITV variation in natural populations. Here, we aimed to (a) measure the relative strength of between- and within-individual effects of body size on ITV over time, and (b) disentangle the trophic changes due to ontogeny from other sources of variability, such as the environment experienced by populations and individual preferences at varying temporal and spatial scales. We used as a model system the endangered marble trout Salmo marmoratus, a freshwater fish living in a restricted geographical area (<900 km 2 ) that shows marked changes in diet through ontogeny. We investigated two trophic traits, trophic position and resource use, with stable isotopes (δ 15 N and δ 13 C), and followed over time 238 individually tagged marble trout from six populations to estimate the trophic changes between and within individuals through ontogeny at three different time-scales (short term: 3 months, medium term: 1 year and long term: 2 years). We found that the relative strength of between- and within-individual effects of body size on trophic position and resource use change strongly over time. Both effects played a similar role in ITV over medium- and long-term time-scales, but within-individual effects were significantly driving trophic variability over short-term scales. Apart from ontogenetic shifts, individuals showed variability in trophic traits as big as the variability estimated between populations. Overall, our results show how the relative strengths of ITV drivers change over time. This study evidences the crucial importance of considering effects of time-scales on functional variability at individual, population and species levels., (© 2019 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.)

Key mechanisms controlling fruit weight and shape at the levels of meristem, ovary or very young fruit have already been identified using natural tomato diversity. We reasoned that new developmental modules prominent at later stages of fruit growth could be discovered by using new genetic and phenotypic diversity generated by saturated mutagenesis. Twelve fruit weight and tissue morphology mutants likely affected in late fruit growth were selected among thousands of fruit size and shape EMS mutants available in our tomato EMS mutant collection. Their thorough characterization at organ, tissue and cellular levels revealed two major clusters controlling fruit growth and tissue morphogenesis either through (i) the growth of all fruit tissues through isotropic cell expansion or (ii) only the growth of the pericarp through anisotropic cell expansion. These likely correspond to new cell expansion modules controlling fruit growth and tissue morphogenesis in tomato. Our study therefore opens the way for the identification of new gene regulatory networks controlling tomato fruit growth and morphology.