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Noninvasive imaging sensors and computer vision approaches are key technologies to quantify plant structure, physiological status, and performance. Today, imaging sensors exploit a wide range of the electromagnetic spectrum, and they can be deployed to measure a growing number of traits, also in heterogenic environments. Recent advances include the possibility to acquire high-resolution spectra by imaging spectroscopy and classify signatures that might be informative of plant development, nutrition, health, and disease. Three-dimensional (3D) reconstruction of surfaces and volume is of particular interest, enabling functional and mechanistic analyses. While taking pictures is relatively easy, quantitative interpretation often remains challenging and requires integrating knowledge of sensor physics, image analysis, and complex traits characterizing plant phenotypes. [Copyright &y& Elsevier]

Experimental evidence on the role of the cell cycle in plant growth regulation does not exclusively fit the cellular (division drives growth) or the organismal perspective (division merely accompanies growth). Here we present a broader, integrated concept of plant growth regulatory interactions, which accommodates experimental results gathered to date. This model can serve as a basis for future research, and prompts experimental approaches to encompass both measurements of cell growth and division parameters. [Copyright &y& Elsevier]

Abstract: In recent years the study of root phenotypic plasticity in response to sub-optimal environmental factors and the genetic control of these responses have received renewed attention. As a path to increased productivity, in particular for low fertility soils, several applied research projects worldwide target the improvement of crop root traits both in plant breeding and biotechnology contexts. To assist these tasks and address the challenge of optimizing root growth and architecture for enhanced mineral resource use, the development of realistic simulation models is of great importance. We review this research field from a modeling perspective focusing particularly on nutrient acquisition strategies for crop production on low nitrogen and low phosphorous soils. Soil heterogeneity and the dynamics of nutrient availability in the soil pose a challenging environment in which plants have to forage efficiently for nutrients in order to maintain their internal nutrient homeostasis throughout their life cycle. Mathematical models assist in understanding plant growth strategies and associated root phenes that have potential to be tested and introduced in physiological breeding programs. At the same time, we stress that it is necessary to carefully consider model assumptions and development from a whole plant-resource allocation perspective and to introduce or refine modules simulating explicitly root growth and architecture dynamics through ontogeny with reference to key factors that constrain root growth. In this view it is important to understand negative feedbacks such as plant–plant competition. We conclude by briefly touching on available and developing technologies for quantitative root phenotyping from lab to field, from quantification of partial root profiles in the field to 3D reconstruction of whole root systems. Finally, we discuss how these approaches can and should be tightly linked to modeling to explore the root phenome. [Copyright &y& Elsevier]

Mitochondria are important sources of energy in plants and are implicated in coordination of a number of metabolic and physiological processes including stabilization of redox balance, synthesis and turnover of a number of metabolites, and control of programmed cell death. Mitochondrial electron transport chain (mETC) is the backbone of the energy producing process which can influence other processes as well. Accumulating evidence suggests that mETC can affect responses to environmental stimuli and modulate tolerance to extreme conditions such as drought or salinity. Screening for stress responses of 13 Arabidopsis mitochondria-related T-DNA insertion mutants, we identified ndufs8. 2-1 which has an increased ability to withstand osmotic and oxidative stresses compared to wild type plants. Insertion in ndufs8. 2-1 disrupted the gene that encodes the NADH dehydrogenase [ubiquinone] fragment S subunit 8 (NDUFS8) a component of Complex I of mETC. ndufs8. 2-1 tolerated reduced water availability, retained photosynthetic activity and recovered from severe water stress with higher efficiency compared to wild type plants. Several mitochondrial functions were altered in the mutant including oxygen consumption, ROS production, ATP and ADP content as well as activities of genes encoding alternative oxidase 1A (AOX1A) and various alternative NAD(P)H dehydrogenases (ND). Our results suggest that in the absence of NDUFS8.2 stress-induced ROS generation is restrained leading to reduced oxidative damage and improved tolerance to water deficiency. mETC components can be implicated in redox and energy homeostasis and modulate responses to stresses associated with reduced water availability. • Complex I subunit NDUFS8.2 is implicated in redox and energy homeostasis. • ndufs8. 2-1 has enhanced tolerance to reduced water availability. • ndufs8. 2-1 mutation reduces mitochondrial respiration. • Genes of mitochondrial alternative bypasses are upregulated in ndufs8. 2-1 mutants. [ABSTRACT FROM AUTHOR]

The vase life sensitivity to mild desiccation (12% weight loss) was addressed in rose, together with alleviation possibilities. The postharvest longevity upon arrival or following mild desiccation was determined on eight cultivars, combined with several morpho-physiological traits. Mild desiccation significantly decreased (10–39%) the vase life of six cultivars (termed sensitive), whereas it did not affect the vase life of two (thus tolerant). More severe desiccation (>12% weight loss) shortened the vase life of a tolerant cultivar. Stomatal control of water loss explained a large part of vase life variation following mild desiccation, whereas cut flower ability to rehydrate or pedicel rigidity (strength, wood density) did not significantly contribute to this variation. Four potentially-mitigating treatments were further tested on the three most sensitive to mild-desiccation cultivars. Antitranspirant treatments [SNP (elicitor of NO) or acetylsalicylic acid in vase water or darkening] decreased the cut flower water loss during the postharvest phase and alleviated the mild-desiccation-induced reduction in vase life. In contrast, Tween 20 (wetting agent) in the vase water shortened vase life. It is concluded that the vase life of previously desiccated cut roses can be extended by employing treatments that reduce the postharvest water loss. [ABSTRACT FROM AUTHOR]

Proline accumulation is one of the most common adaptive responses of higher plants against abiotic stresses like drought. It plays multiple roles in osmotic adjustment, cell homeostasis and stress recovery. Genetic regulation of proline accumulation under drought is complex, and transcriptional cascades modulating proline is poorly understood. Here, we employed quadruple mutant (abf1 abf2 abf3 abf4) to dissect the role of ABA-responsive elements (ABREs) binding transcription factors (ABFs) in modulating proline accumulation across varying stress scenarios. ABREs are present across the promoter of the P5CS1 gene, whose upregulation is considered a hallmark for drought inducible proline accumulation. Upon ABA treatment, P5CS1 mRNA expression and proline content in the shoot were significantly higher in Col-0 compared to the quadruple mutant. Similar results were found at 2 h and 3 h after acute dehydration. We quantified proline at different time points after drought stress treatment. The proline content was higher in wild type (Col-0) than the quadruple mutant at the early stage of drought. Notably, the proline accumulation in wild type increased at a slower rate than the quadruple mutant 7 d after drought stress. Besides, the quadruple mutant displayed significant oxidative damage, low tissue turgidity and higher membrane damage under terminal drought stress. Both terminal drought stress and long-term constant water stress revealed substantial differences in growth rate between wild type and quadruple mutant. The study provides evidence that ABFs are involved in drought stress response, such as proline biosynthesis in Arabidopsis. [ABSTRACT FROM AUTHOR]

Unfavorable environmental conditions limit plant growth and require extensive adaptation for survival. During abiotic stress, production of reactive oxygen species (ROS) can increase and create additional oxidative stress for the plants. Mitochondria regulate cellular energy homeostasis and redox balance by integrating metabolic pathways that are important in adaptive responses to stress conditions. In mitochondria, over-reduction of the electron transport chain is the primary reason for ROS accumulation, which can be reduced by protecting and stabilizing the electron flow. To reveal the function of genes encoding members of the mitochondrial electron transport in stress responses, we are characterizing 13 Arabidopsis thaliana mutants carrying mutations in genes encoding such proteins. When compared to wild type several mutants showed morphological and physiological changes under abiotic stress conditions. Phenotypic differences in tolerance to drought and salinity were revealed through in vitro germination and growth tests, as well as by complex phenotyping of soil-grown plants. Several mutants showed altered tolerance to osmotic, oxidative and salt stress. In some cases, we found a strong correlation between the mutations and the photosynthetic activity and energy production. [ABSTRACT FROM AUTHOR]