Javier Botto - Academia.edu (original) (raw)

Papers by Javier Botto

ABSTRACTRoot Hairs (RHs) growth is highly influenced by endogenous as well as by external environ... more ABSTRACTRoot Hairs (RHs) growth is highly influenced by endogenous as well as by external environmental signals that coordinately regulate its final cell size. RHs actively expand the root surface responsible for nutrient uptake and water absorption. We have recently determined that RH growth was unexpectedly boosted when Arabidopsis thaliana seedlings are cultivated at low temperatures. It was proposed that RH growth plasticity in response to low temperature was linked to a reduced nutrient availability in the media. Here, we explored the molecular basis of this strong RH growth response by using the Genome Wide Association Studies (GWAS) approach on Arabidopsis thaliana natural accessions. We identified the poorly characterized PEROXIDASE 62 (PRX62) as a key protein triggering this conditional growth under a moderate low-temperature stress. In addition, we identified the related protein PRX69 as an important factor in this developmental process. The prx62 prx69 double mutant and t...

Frontiers in Plant Science, 2021

Arabidopsis thaliana shows a wide range of genetic and trait variation among wild accessions. Bec... more Arabidopsis thaliana shows a wide range of genetic and trait variation among wild accessions. Because of its unparalleled biological and genomic resources, Arabidopsis has a high potential for the identification of genes underlying ecologically important complex traits, thus providing new insights on genome evolution. Previous research suggested that distinct light responses were crucial for Arabidopsis establishment in a peculiar ecological niche of southern Patagonia. The aim of this study was to explore the genetic basis of contrasting light-associated physiological traits that may have mediated the rapid adaptation to this new environment. From a biparental cross between the photomorphogenic contrasting accessions Patagonia (Pat) and Columbia (Col-0), we generated a novel recombinant inbred line (RIL) population, which was entirely next-generation sequenced to achieve ultra-high-density saturating molecular markers resulting in supreme mapping sensitivity. We validated the quali...

Plant Communications, 2021

Plant Physiology, 2018

B-box (BBX) proteins are zinc-finger transcription factors containing one or two B-box motifs. BB... more B-box (BBX) proteins are zinc-finger transcription factors containing one or two B-box motifs. BBX proteins act as key factors in the networks regulating growth and development. The relevance of BBX21 to light and abscisic acid signaling in seedling development is well established; however, its importance in adult plant development and agronomic species is poorly understood. Therefore, we studied the effect of heterologous expression of Arabidopsis (Arabidopsis thaliana) BBX21 in potato (Solanum tuberosum) var Spunta. Three independent AtBBX21-expressing lines and the wild-type control were cultivated under sunlight and at controlled temperatures in a greenhouse. By anatomical, physiological, biochemical, and gene expression analysis, we demonstrated that AtBBX21-expressing plants were more robust and produced more tubers than wild-type plants. Interestingly, AtBBX21-expressing plants had higher rates of photosynthesis, with a significant increase in photosynthetic gene expression, and higher stomatal conductance, with increased size of the stomatal opening, without any associated decline in water use efficiency. Furthermore, AtBBX21-expressing potato plants had reduced photoinhibition associated with higher production of anthocyanins and phenolic compounds, and higher expression of genes in the phenylpropanoid biosynthesis pathway. To gain insights into the mechanism of BBX21, we evaluated the molecular, morphological, metabolic, and photosynthetic behavior in adult BBX21-overexpressing Arabidopsis. We conclude that BBX21 overexpression improved morphological and physiological attributes, and photosynthetic rates in nonoptimal, high-irradiance conditions, without associated impairment of water use efficiency. These characteristics of BBX21 may be useful for increasing production of potatoes, and potentially of other crops.

Weed Science, 1998

The purpose of this study was to investigate the role of sunlight perceived by weed seeds during ... more The purpose of this study was to investigate the role of sunlight perceived by weed seeds during and after soil cultivation with moldboard and chisel plows on induction of seed germination. Daytime cultivation with a moldboard plow increased weed seedling emergence by as much as 200% above the levels recorded following nighttime cultivation; however, the magnitude of this promotion varied depending on season and field history, and occasionally it was nil. In contrast, when a chisel plow was used in primary tillage, no differences in seedling emergence were observed between daytime and nighttime cultivation. The absolute germination level in plots cultivated with a chisel plow was at least 200% greater than in plots cultivated with a moldboard plow. This observation suggests that microenvironmental factors other than light played an important role in promoting seed germination in chisel-plowed plots. Covering moldboard-plowed plots with opaque plastic immediately after cultivation di...

International Journal of Plant Sciences, 2017

Premise of research. Plants cope with complex environments throughout their life cycles. The perc... more Premise of research. Plants cope with complex environments throughout their life cycles. The perception and integration of information acquired from different environmental parameters are key to responding appropriately and securing plant survival. In Arabidopsis thaliana, SALT OVERLY SENSITIVE 2 (SOS2) and SOS3, its protein-interacting partner, have been described as central players in salt-stress responses, while another SOS2-interacting partner, ABSCISIC ACID (ABA)-INSENSITIVE 2 (ABI2), is involved in ABA signaling. SOS2 was also suggested to be involved in the photocontrol of seed germination, although its function in photomorphogenesis is not fully understood. Here we studied the role played by SOS2, SOS3, and ABI2 in light-dependent responses in Arabidopsis mutants. We assessed whether SOS2, SOS3, and ABI2 modulate light-and hormoneregulated seed germination and seedling deetiolation. Methodology. We examined physiological responses in wild-type and SOS2, SOS3, and ABI2 knockout mutants of A. thaliana exposed to red light and explored whether these proteins modulate germination (by changing hormone sensitivity) and seedling deetiolation. In addition, we analyzed the presence of cis-regulatory elements (CREs) in their promoters and expression profiles from public microarrays to confirm their function in photomorphogenesis. Pivotal results. Germination experiments demonstrate that SOS2, SOS3, and ABI2 are positive regulators of germination induced by red light. Differences in germination between the wild type and mutants are explained by changes in gibberellin sensitivity. Analysis of hypocotyl growth inhibition and cotyledon opening suggest that these components are also required for full seedling deetiolation under red light. Furthermore, identification of CREs in gene promoters and expression analysis matched the proposed role for these genes in both processes. Conclusions. SOS2, SOS3, and ABI2 are known components of salt signaling, and here we demonstrate that they are also positive elements of light signaling by regulating seedling deetiolation and altering gibberellic acid sensitivity during germination. These results suggest that they act as integrators of different signaling pathways.

Nature Communications, 2015

In response to canopy shade, plant vegetative structures elongate to gain access to light. Howeve... more In response to canopy shade, plant vegetative structures elongate to gain access to light. However, the mechanism that allows a plastic transcriptional response to canopy shade light is not fully elucidated. Here we propose that the activity of PIF4, a key transcription factor in the shade signalling network, is modulated by the interplay between the BBX24 transcriptional regulator and DELLA proteins, which are negative regulators of the gibberellin (GA) signalling pathway. We show that GA-related targets are enriched among genes responsive to BBX24 under shade and that the shade-response defect in bbx24 mutants is rescued by a GA treatment that promotes DELLA degradation. BBX24 physically interacts with DELLA proteins and alleviates DELLA-mediated repression of PIF4 activity. The proposed molecular mechanism provides reversible regulation of the activity of a key transcription factor that may prove especially relevant under fluctuating light conditions.

The Plant Journal, 2010

Plants grown at high densities perceive the reduction in the ratio of red (R) to far-red (FR) lig... more Plants grown at high densities perceive the reduction in the ratio of red (R) to far-red (FR) light as a warning of competition. This light signal triggers morphological responses such as hypocotyl and stem elongation, and acceleration of flowering, which are known collectively as the shade-avoidance syndrome (SAS). Mutations in the photomorphogenic repressor COP1 suppress the SAS, but how COP1 modulates these responses is uncertain. We identified a new mutant with altered responses to natural shade, named lhus (long hypocotyl under shade). lhus seedlings have longer hypocotyls than wild-type under a low R:FR ratio, but not under sunlight or darkness. The lhus phenotype is due to a mutation affecting a B-box zinc finger transcription factor encoded by At1g75540, a gene previously reported as AtBBX21 that interacts with COP1 to control de-etiolation. Mutations in genes encoding other members of this protein family also result in impaired SAS regulation. Under short-term canopy shade, LHUS/BBX21 acts as positive regulator of SAS genes such as PAR1, HFR1, PIL1 and ATHB2. In contrast, global expression analysis of wild-type and lhus/bbx21 seedlings revealed that a large number of genes involved in hormonal signalling pathways are negatively regulated by LHUS/BBX21 in response to long-term canopy shade, and this observation fits well with the phenotype of lhus/bbx21 seedlings grown under a low R:FR ratio. Moreover, the bbx21 bbx22 double mutation restored the SAS in the cop1 background. We propose that LHUS/BBX21 and other B-box-containing proteins, such as BBX22, act downstream of COP1, and play a central role in early and long-term adjustment of the SAS in natural environments.

PLANT PHYSIOLOGY, 2005

We used 52 Arabidopsis (Arabidopsis thaliana) accessions and developed a new set of 137 recombina... more We used 52 Arabidopsis (Arabidopsis thaliana) accessions and developed a new set of 137 recombinant inbred lines between Landsberg erecta (Ler) and Nossen (No-0) to explore the genetic basis of phytochrome-mediated responses during deetiolation. Unexpectedly, most accessions showed weak or moderate hypocotyl growth and cotyledon unfolding responses to pulses of far-red light (FR). Crosses between Columbia and No-0, two accessions with poor response, segregated seedlings with unfolded cotyledons under pulsed FR, suggesting the occurrence of accession-specific loci in the repression of morphological responses to weak light signals. Confirming the latter expectation, mapping of responses to pulsed FR in the Ler × No-0 lines identified novel loci. Despite its weak response to pulsed FR, No-0 showed a response to continuous FR stronger than that observed in Ler. By mapping the differential effect of pulsed versus continuous FR, we identified two high-irradiance response loci that account...

Journal of Plant Physiology, 1995

... of dry-stored seeds responds both to natural and simulated shadelight (Taylorson and Borthwic... more ... of dry-stored seeds responds both to natural and simulated shadelight (Taylorson and Borthwick, 1969; Frankland and Poo, 1980; Vazquez-Yaiiez and ... Re © 1995 by Gustav Fischer Verlag, Stuttgart versibility by FR is often not possible since FR itself establishes sufficient Pfr to ...

Journal of Experimental Botany, 1998

through largely unknown pathways into molecular and physiological changes that modulate growth an... more through largely unknown pathways into molecular and physiological changes that modulate growth and develop-Phytochrome is a family of photoreceptors whose ment. Phytochromes posses two photo-interconvertible apoproteins are encoded by divergent genes. Three forms, the R-absorbing form (Pr) and the FR-absorbing modes of action of phytochromes, very-low-fluence form (Pfr) and are synthesised in the Pr form. In recent responses (VLFR), low-fluence responses (LFR) and years it has been established that phytochromes are a high-irradiance responses (HIR), have been considered small family of photoreceptors whose apoproteins are in the literature to define the quantitative relationship encoded by different genes (Clack et al., 1994; Hauser between response and predicted levels of the far-red et al., 1995). Traditionally, three 'modes of action' of light absorbing form of phytochrome. The results of phytochromes have been described: very-low-fluence recent experiments with phytochrome mutant and responses (VLFR); low-fluence responses (LFR) and transgenic seedlings are consistent with the notion high-irradiance responses (HIR). Assigning particular that phytochrome B, and in some cases other stable responses to particular molecular species of phytochromes phytochromes, mediate LFR whereas phytochrome A is one of the important areas of research in the field mediates both VLFR and HIR. The mechanisms of photomorphogenesis. This review seeks to bring involved in phytochrome A inductive responses (VLFR) together data on the modes of action of phytochrome versus HIR appear to be different in some ways. with information on different phytochrome molecular However, VLFR, LFR and HIR can converge to control species. the transcriptional activity of a single gene promoter. The analysis of phytochrome transduction chains is The implications of these findings for the undercurrently concentrating the efforts of many laboratories. standing of phytochrome phototransduction are Experimental approaches include the characterization of discussed. the photoreceptor molecule, in particular the biological significance of different domains (Cherry et al., 1993; Key words: Arabidopsis thaliana, high-irradiance Boylan et al., 1994; Xu et al., 1995), the characterization responses, low-fluence responses, phytochrome, very-lowof cis and trans acting elements controlling transcription fluence responses. (for review see Terzaghi and Cashmore, 1995), the identification of mutants exhibiting deficient skotomorphogenesis or photomorphogenesis (Pepper et al., 1994;

Plant Signaling & Behavior, 2011

Frontiers in Plant Science

HortScience

The phytochromes, a family of photoreceptors that maximally absorb red (R) and far-red (FR) light... more The phytochromes, a family of photoreceptors that maximally absorb red (R) and far-red (FR) light, play an important role in defining the architecture of the plant and consequently its value in the market. In this work, we evaluated the manipulation of light quality as an alternative to the use of plant growth regulators (PGRs) to produce poinsettia plants (Euphorbia pulcherrima Willd. ex Klotzsch) without affecting commercial quality parameters. ‘Freedom Red’ poinsettia plants were cultivated in two light environments characterized by different R/FR ratios in combination with or without one application of PGR. We used a photoselective film that significantly reduced the FR component of the light and a transparent film to obtain high and low R/FR ratios (5.7 and 1.1, respectively). Plants cultivated under a high R/FR ratio were shorter and more compact than those grown under transparent film. Other quality characters like bract and leaf area, dry weight, stem diameter, number of lat...