Combining the Seed Endophytic Bacteria and the Back to the Future Approaches for Plant Holonbiont Breeding

Given the limits of intensive agriculture (pollution, degradation of biodiversity, or soil desertification), it is necessary to develop sustainable alternatives to respond to future agricultural demand. Among these sustainable alternatives is the use of microbial biostimulants. Despite convincing scientific studies on them, their agricultural use remains minor. This can be explained by the lack of efficiency and reliability of their use. This review proposes to develop efficient microbial biostimulants based on the combination of two approaches, namely that of endophytic bacteria from seeds and the Back to the Future approach. Seed endophytic bacteria have a major agroindustrial potential insofar as they stand out from other microbial agents by their resistance, competitiveness, efficiency, and vertical transmission. Contrary to modern cultivars, non-domesticated plants harbor microbiomes which have not been impacted by the processes of domestication and agriculture intensification. The Back to the Future suggests therefore to use interesting microorganisms isolated from non-domesticated plants and to integrate them into modern cultivars. This could result in the rehabilitation of modern microbiomes and lead to make crop cultures more resistant and resilient. The idea consisting in the combination of both approaches aims at obtaining optimized microbiomes. Particular emphasis is placed on integrating these innovative microbiomes into variety breeding programs. Indeed, given the importance of plant-microorganism interactions, particularly from an agronomic point of view, taking the hologenome into account as a unit of selection in breeding programs is essential. This integrative and unprecedented approach to designing breeding programs is promising with a view to reconciling productivity and preservation of agroecosystems.

EFFECTS OF LAND-USE INTENSIFICATION AND ENVIRONMENTAL STRESSORS ON INTRASPECIFIC FUNCTIONAL TRAITS VARIABILITY IN BUMBLEBEES

ABSTRACTLandscape anthropization replaces natural areas with either agricultural or urban covers, leading to land-use intensification. This worldwide phenomenon affects biodiversity, but little is known about the effects on the intraspecific variation of functional traits in spite of their importance for ecosystem functioning and services.Here we investigated if the functional traits of pollinator insects responded to land-use intensification and environmental stressors, by characterizing the variation of important traits for flight performance that are also indicators of stressors during organism development. The possible impact of different land cover (i.e. semi-natural, urban and agricultural) and of multiple biotic and abiotic stressors (i.e. temperature, resource availability and air pollutants) was investigated.Along a gradient of landscape anthropization, we quantified the impact of biotic and abiotic factors on two European bumblebee species (Bombus terrestris and B. pascuorum) sampled at 37 sites in Northern Italy. Through geometric morphometrics we investigated the variation of multiple morphological traits, namely wing centroid size (as a proxy of body size) and asymmetry of wing shape and size. Data on land-cover, climatic conditions and air pollutants were retrieved through remote sensing, while the estimation of resource availability was conducted directly in the field.Our results highlighted the relevance of the two main land-use alteration trajectories (i.e. urbanization and agriculture intensification), although the two species responded idiosyncratically. Urbanization led to shifts towards smaller body sizes due to increased impervious cover and air temperature in B. pascuorum. Instead, B. terrestris responded to agriculture intensification with larger body size in response to higher farmland cover and floral resource availability. Asymmetry in wing shape was not affected by abiotic factors of land-use intensification, but wing size asymmetry was positively associated with warmer temperatures and increased level of NO2 in B. terrestris.This study describes patterns of how landscape anthropization shapes pollinator insects’ functional traits: urbanization is associated with smaller bees, while agriculture intensification leads to larger bees. In addition, environmental stressors impacted wing size asymmetries and could compromise flight performance, particularly in warmer, more polluted habitats. This study indicates that the land-use intensification of anthropized landscapes determines functional trait variation at the intraspecific level and that these responses are highly taxon-specific even in syntopic related organisms.

Farmland Fragmentation, Farmland Consolidation and Food Security: Relationships, Research Lapses and Future Perspectives

Farmland fragmentation and farmland consolidation are two sides of the same coin paradoxically viewed as farmland management tools. While there is a vast body of literature addressing the connections between farmland fragmentation and farmland consolidation on the one hand and agriculture production and crops diversification on the other hand, their relationship with variations in food security is still under-explored. This challenges policy makers about whether and how to devise policies in favor of fragmentation conservation or defragmentation. Therefore, drawing on the multiple secondary data and the deductive logical reasoning through an integrative concept-centric qualitative approach following the rationalist theory, this study critically reviews and analyses the existing body of literature to identify how farmland fragmentation versus defragmentation approaches relate to food security. The goal is to develop and derive an explicit model indicating when, where, how and why farmland fragmentation can be conserved or prevented and controlled for food security motives as a novel alternative comprehensive scientific knowledge generation, which could guide and inform the design of future research and policies about farmland fragmentation management. The findings show that both fragmentation and consolidation variously (positively and negatively) impact on food security at different (macro, meso and micro) levels. While farmland fragmentation is highly linked with food diversification (food quality), acceptability, accessibility, and sovereignty at the local (household and individual) levels, farmland consolidation is often associated with the quantity and availability of food production at the community, regional and national levels. Theoretically, the best management of farmland fragmentation for food security purposes can be achieved by minimizing the problems associated with physical and tenure aspects of farmland fragmentation along with the optimization of its potential benefits. In this regard, farmland consolidation, voluntary parcel exchange and on-field harvest sales, farmland realignment, and farmland use (crop) consolidation can be suitable for the control of physical fragmentation problems under various local conditions. Similarly, farmland banking and off-farm employment, restrictions about the minimum parcel sizes subdivision and absentee owners, joint ownership, cooperative farming, farmland use (crop) consolidation, agricultural land protection policies, and family planning measures can be suitable to prevent and minimize farmland tenure fragmentation problems. On the other hand, various agriculture intensification programs, agroecogical approaches, and land saving technologies can be the most suitable strategies to maximize the income from agriculture on fragmented plots under the circumstances of beneficial fragmentation. Moreover, in areas where both rational and defective fragmentation scenarios coexist, different specific strategies like localized and multicropping based land consolidation approaches in combination with or without agriculture intensification programs, can provide better and more balanced optimal solutions. These could simultaneously minimize the defective effects of fragmentation thereby optimizing or without jeopardizing its potential benefits with regard to food security under specific local conditions.