Brassinosteroids Mitigate Cadmium Effects in Arabidopsis Root System without Any Cooperation with Nitric Oxide

The heavy metal cadmium (Cd) affects root system development and quiescent center (QC)-definition in Arabidopsis root-apices. The brassinosteroids-(BRs)-mediated tolerance to heavy metals has been reported to occur by a modulation of nitric oxide (NO) and root auxin-localization. However, how BRs counteract Cd-action in different root types is unknown. This research aimed to find correlations between BRs and NO in response to Cd in Arabidopsis’s root system, monitoring their effects on QC-definition and auxin localization in root-apices. To this aim, root system developmental changes induced by low levels of 24-epibrassinolide (eBL) or by the BR-biosynthesis inhibitor brassinazole (Brz), combined or not with CdSO4, and/or with the NO-donor nitroprusside (SNP), were investigated using morpho-anatomical and NO-epifluorescence analyses, and monitoring auxin-localization by the DR5::GUS system. Results show that eBL, alone or combined with Cd, enhances lateral (LR) and adventitious (AR) root formation and counteracts QC-disruption and auxin-delocalization caused by Cd in primary root/LR/AR apices. Exogenous NO enhances LR and AR formation in Cd-presence, without synergism with eBL. The NO-signal is positively affected by eBL, but not in Cd-presence, and BR-biosynthesis inhibition does not change the low NO-signal caused by Cd. Collectively, results show that BRs ameliorate Cd-effects on all root types acting independently from NO.

SINGLE AND COMBINED ABIOTIC STRESSES IMPACT THE ROOT EXUDATION PATTERNS IN DIFFERENT MAIZE ROOT TYPES

Root exudates play an essential role in plant-soil-abiotic stress interactions. However, we still know little about the influence of stress combinations on the root exudation profile. Using targeted and untargeted metabolomics, here we test the effect of drought, heat stress, and their combination on the maize root exudates, also considering the differences that might exist between root types (seminal and primary) and root zones (apical and sub-apical). In addition, we built an analytical framework that relate the root exudation profile with the characterization of the rhizosphere bacterial community, enabling us to dissect the interactions between specific root exudates and microbial taxa. Our results suggest that the composition of root exudates has a different outcome according to the single or combined stress and to the root zone but not between root types. Further, we found that stress-specific exudates influence the relative abundance of specific microbial taxa, some of which are known to be beneficial microorganisms. Therefore, the stress-specific root exudate composition selecting specific microbial taxa, here observed, represent a contribute on the effects of climate changes on crops increasing thus the potential impact on the current trend of crafting agricultural practices within a wider point of view of plants-microbe-environment interactions.

Advances in understanding plant root anatomy and nutrient acquisition

In this chapter root anatomical traits and trait states, and nutrient acquisition mechanisms, along with the environmental issues affecting nutrient acquisition are summarized. Then, the whole range of adaptations of root anatomical traits, and its impact on nutrient acquisition are discussed. Combinations of anatomical traits lead to suggestions of root ideotypes potentially capable of supporting agricultural productivity under different edaphic constraints. Spatiotemporal aerenchyma formation in the various root types of maize under nitrate, phosphate or sulfate deprivation is discussed in a case study.

IDENTIFIKASI JENIS DAN POTENSI BAMBU (Bambusasp.) SEBAGAI SENYAWA ANTIMALARIA

Malaria is still a health problem in Indonesia caused by the protozoan genus Plasmodium through the bite of the Anopheles mosquito. One of the plants that can also be used to treat fever caused by parasitic diseases is bamboo (Bambusa sp.). The purpose of this research is to identify the type and potential of bamboo as an antimalarial compound in Lampung Province. This research be able to provide an overview of the diversity of bamboo species and their potential as an antimalaria compound in Lampung Provincein May-July 2020. Primary data collection methods were obtained directly in the field including bamboo stands, both growing wild and cultivating, and describing them. Morphological observations for identification such as rhizome root types; bamboo shoots; branching; culm; leaf; stem; and segments refer to the criteria used by Widjaja (1997). The data is analyzed descriptively and tabulated. The results obtained 14 species of bamboo consisting of 5 genera with 14 species: Gigantochloa robusta, Schizostachyum brachycladum (Kurz), Schizostachyum blumei, Gigantochloa atroviolacea, Gigantochloa pseudoarundinacea (Steud.), Bambusa vulgaris var. striata (Lodd.ex Lindl.), Gigantochloa apus (Kurz), Dendrocalamus strictus, Bambusa maculate (Widjaja), Bambusa glaucophylla (Widjaja), Dendrocalamus asper (Backer ex K. Heyne), Dinochloa scandens (Blume ex Nees Kuntze), Bambusa glaucophylla (Widjaja), Dendrocalamus asper (Backer ex K. Heey), Dinochloa scandens (Blume ex Nees Kuntze), Bambusa multiplex (Lour.) Raeusch. Ex Schult and Bambusa blumeana (Schult.f). Bamboo has the potential for crafts, construction, food, medicine (bamboo shoots from Bambusa vulgaris var. Striata, Gigantochloa apus leaves and water from Dinochloa scandens bamboo stems).Kata kunci: antimalarial,bamboo

Single and Combined Abiotic Stress in Maize Root Morphology

Plants are continually exposed to multiple stresses, which co-occur in nature, and the net effects are frequently more nonadditive (i.e., synergistic or antagonistic), suggesting “unique” responses with respect to that of the individual stress. Further, plant stress responses are not uniform, showing a high spatial and temporal variability among and along the different organs. In this respect, the present work investigated the morphological responses of different root types (seminal, seminal lateral, primary and primary lateral) of maize plants exposed to single (drought and heat) and combined stress (drought + heat). Data were evaluated by a specific root image analysis system (WinRHIZO) and analyzed by uni- and multivariate statistical analyses. The results indicated that primary roots and their laterals were the types more sensitive to the single and combined stresses, while the seminal laterals specifically responded to the combined only. Further, antagonistic and synergistic effects were observed for the specific traits in the primary and their laterals and in the seminal lateral roots in response to the combined stress. These results suggested that the maize root system modified specific root types and traits to deal with different stressful environmental conditions, highlighting that the adaptation strategy to the combined stress may be different from that of the individual ones. The knowledge of “unique or shared” responses of plants to multiple stress can be utilized to develop varieties with broad-spectrum stress tolerance.

Connecting the dots between root cross-section images and modelling tools to create a high resolution root system hydraulic maps in Zea mays.

Root hydraulic properties play a central role in the global water cycle, agricultural systems productivity, and ecosystem survival as they impact the global canopy water supply. However, the available experimental methods to quantify root hydraulic conductivities, such as the root pressure probing, are particularly challenging and their applicability on thin roots and small root segments is limited. There is a gap in methods enabling easy estimations of root hydraulic conductivities across a diversity of root types and at high resolution along root axes. In this case study, we analysed Zea mays (maize) plants of the var. B73 that were grown in pots for 14 days. Root cross-section data were used to extract anatomical measurements. We used the Generator of Root Anatomy in R (GRANAR) model to generate root anatomical networks from anatomical features. Then we used the Model of Explicit Cross-section Hydraulic Anatomy (MECHA) to compute an estimation of the root axial and radial hydraulic conductivities (kx and kr, respectively), based on the generated anatomical networks and cell hydraulic properties from the literature. The root hydraulic conductivity maps obtained from the root cross-sections suggest significant functional variations along and between different root types. Predicted variations of kr along the root axis were strongly dependent on the maturation stage of hydrophobic barriers. The same was also true for the maturation rates of the metaxylem. The different anatomical features, as well as their evolution along the root type add significant variation to the kr estimation in between root type and along the root axe. Under the prism of root types, anatomy, and hydrophobic barriers, our results highlight the diversity of root radial and axial hydraulic conductivities, which may be veiled under low-resolution measurements of the root system hydraulic conductivity. While predictions of our root hydraulic maps match the range and trend of measurements reported in the literature, future studies could focus on the quantitative validation of hydraulic maps. From now on, a novel method, which turns root cross-section images into hydraulic maps will offer an inexpensive and easily applicable investigation tool for root hydraulics, in parallel to root pressure probing experiments.