Here we investigated changes in primary metabolism and cell death around oviposition sites in two hybrid clones of Eucalyptus with different degree of resistance to Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae), as well as, tolerance to water deficiency. We showed that apices of the resistant clone with oviposition had a higher content of amino acids organic acids, and the compound putrescine, than those of the susceptible clone with oviposition. In contrast, apices of the resistant clone with oviposition had lower sugar content and pyruvate organic acid content than those of the susceptible clone with oviposition. Small areas of necrosis were induced around the oviposition sites in the stem apices of Eucalyptus 24 h after infestation. The resistant clone developed larger necrotic areas that showed progressive increases 24–72 h after infestation than the susceptible clone, in which cell death was significantly lower and no changes were observed in necrotic area over time. Thus, the programmed death of cells around the egg, modulated by several amino acids, is likely the first defence response of Eucalyptus against L. invasa. Our results serve as the basis for the early identification of key metabolites produced in plants in defence against galling insects.

In cellular circumstances where carbohydrates are scarce, plants can use alternative substrates for cellular energetic maintenance. In plants, the main protein reserve is present in the chloroplast, which contains most of the total leaf proteins and represents a rich source of nitrogen and amino acids. Autophagy plays a key role in chloroplast breakdown, a well-recognized symptom of both natural and stress-induced plant senescence. Remarkably, an autophagic-independent route of chloroplast degradation associated with Chloroplast Vesiculation (CV) gene was recently demonstrated. During extended darkness, CV is highly induced in the absence of autophagy, contributing to the early senescence phenotype of atg mutants. To further investigate the role of CV under dark-induced senescence conditions, mutants with low expression of CV ( amircv) and double mutants amircv1xatg5 were characterized. Following darkness treatment, no aberrant phenotypes were observed in amircv single mutants; however, amircv1xatg5 double mutants displayed early senescence and enhanced dismantling of chloroplast and membrane structures under these conditions. Metabolic characterization revealed that the functional lack of both CV and autophagy leads to higher impairment of amino acid release and differential organic acid accumulation during starvation conditions. The data obtained are discussed in the context of the role of CV and autophagy, both in terms of cellular metabolism and the regulation of chloroplast degradation.

Cells, tissues, and organs harbour complex systems to allow communication between one another. The biological rhythms can be contrasting among organs, tissues, and cells, adjusting the physiology differently along the organism‘s regions. while also synchronising flowering and metabolism. Here, we revealed that Solanum lycopersicum manifests more balanced rhythms across the whole plant than wild tomatoes. Accordingly, the leaf development program is more coordinated in this organism than in wild species, in that young S. lycopersicum leaves develop slowly in comparison to mature leaves. Young leaves from wild tomatoes display higher photosynthetic rate than mature leaves, while large metabolite accumulations occur across plant segments. Consequently, diel metabolite levels are rather similar between young and mature leaves in the wild tomato S. pennellii, whereas the expression patterns for circadian clock genes are widely contrasting between differently aged leaves. We further demonstrated that introduction of domestication alleles into the wild tomato S. pimpinellifolium appears to synchronize the development of young and mature leaves, rendering this similar to that observed for S. lycopersicum. Collectively, the strengthening of inter-organ relationships in S. lycopersicum indicates an increased synchronization of its biology, which is probably fundamental to explain its elevated yield.