Quinoa (Chenopodium quinoa Willd.) is a highly nutritious crop with remarkable tolerance to drought and salinity, making it a promising model for developing resilient crops. In model plant species, photoreceptors have been shown to mediate abiotic stress responses. Although quinoa’s tolerance mechanisms have been extensively investigated, the influence of light on its growth and stress responses remains largely unexplored. This study evaluated the effects of broad-spectrum white light supplemented with narrow-bandwidth light on quinoa vegetative development under non-saline and moderate salinity conditions. Four genotypes were tested: two commercial varieties and two local Ecuadorian landraces. Light quality influenced physiological responses in a genotype-dependent manner. Supplemental far-red light promoted greater plant height under both control and salt conditions. Supplemental red light enhanced biomass accumulation under control conditions but not under salinity, suggesting that red light–mediated growth promotion may be constrained by higher salinity. Conversely, supplemental blue light mitigated the negative effects of salinity on growth, indicating a potential role as a positive mediator for salt tolerance in the species. The presence of salt altered several light-driven responses, supporting an interaction between responses to light and salt stress signaling. Our findings highlight the importance of incorporating light-related variables into quinoa stress physiology research which could ultimately provide breeding insights to enhance crop resilience through targeted photoreceptor breeding.

SR proteins are conserved RNA-binding proteins best known as splicing regulators that have also been implicated in other steps of gene expression. Despite mounting evidence for a role in plant development and stress responses, the molecular pathways underlying SR protein regulation of these processes remain poorly understood. Here we show that the plant-specific SCL30a SR protein negatively regulates ABA signaling to control seed traits and stress responses during germination in Arabidopsis. Transcriptome-wide analyses revealed that loss of SCL30a function barely affects splicing, but largely induces ABA-responsive gene expression and genes repressed during germination. Accordingly, scl30a mutant seeds display delayed germination and hypersensitivity to ABA and high salinity, while transgenic plants overexpressing SCL30a exhibit reduced ABA and salt stress sensitivity. An ABA biosynthesis inhibitor rescues the enhanced mutant seed stress sensitivity, and epistatic analyses confirm that this hypersensitivity requires a functional ABA pathway. Finally, seed ABA levels are unchanged by altered SCL30a expression, indicating that the gene promotes seed germination under stress by reducing sensitivity to the phytohormone. Our results reveal a new player in ABA-mediated control of early development and stress response.

Guayusa (Ilex guayusa) is an endemic plant from the Amazon with potential medicinal applications. Indigenous people are familiar with such applications and use guayusa based on ancestral knowledge. There is a growing interest in guayusa-based products in urban areas of Ecuador and internationally. The supply cannot meet the demand. Currently, traditional practices are used for guayusa growth and the potential use of the protected forest is foreseen. This work describes a protocol for the in vitro propagation of guayusa, a sustainable solution to generate high quality plants in reduced space. Stakes obtained from stems were used as explants. Chemical sterilization with ethanol and sodium hypochlorite resulted in 100% surface-sterilized stakes. The growth medium mWPM resulted in favorable outcomes regarding shoot development and elongation, as well as rooting. Supplementation with activated charcoal resulted in reduced browning, only 10% of the shoots presented necrosis during the elongation phase. More than two thirds of shoots were able to develop roots spontaneously. Medium supplementation with the auxin indole-3-butyric acid, IBA, may be considered when rooting does not occur spontaneously. Acclimatization was performed in soil. The protocol was tested under different light spectra, revealing that guayusa growth is affected by light quality. The photobiology of this shade tolerant plant requires further characterization, but the data uncovered a potential role for green and far-red light in root development. Guayusa was propagated on mWPM medium supplemented with activated charcoal. Spontaneous root development occurred in most shoots. Light quality affected plant development, green and far-red light could influence root growth.

There is substantial interest in growing crops in closed controlled environments, yet the energy requirements are high. Energy is required to produce light, but also to remove the heat generated when producing light. The goal of the current work examines a possible approach to decrease the energy requirement. The effect of pulsed light treatments was examined by monitoring seedling traits during early photomorphogenic development. Daily light integral remained unchanged between treatments, but the frequency of the pulses was varied. Developmental traits (such as inhibition of hypocotyl elongation rate) were most conspicuous during a normal photoperiod, as in twelve hours light, twelve hours darkness. Consistent with historical reports, when treatments were delivered in shorter durations (e.g. 1 hour on/off) photomorphogenic development was hindered, with the same daily light integral. However, at even shorter light intervals (e.g. seconds) seedlings developed as if they were provided full 12 h treatments. Extension of the dark period following a 5 s pulse was tested to determine the effect on seedling traits. The results showed that the dark period could be extended to at least 10 s without affecting seedling development, and extension to 20 s only had slight effects on seedling traits. The mechanism of the phenomenon was examined in Arabidopsis photosensory mutants, with substantial contributions from the phyA and cry1 pathways. The results suggest that pulsed light with extended dark periods can decrease energy input by at least 30% to >50% without affecting visible seedling traits. These pilot experiments in seedlings demonstrate that implementation of short-interval, pulsed-light strategies may lower energy requirements for growing crops in artificially illuminated environments.

Plant-phyllosphere interactions depend on microbial diversity, the plant host and environmental factors. Light is perceived by plants and by microorganisms and is used as a cue for their interaction. Photoreceptors respond to narrow-bandwidth wavelengths and activate specific internal responses. Light-induced plant responses include changes in hormonal levels, production of secondary metabolites, and release of volatile compounds, which ultimately influence plant-phyllosphere interactions. On the other hand, microorganisms contribute making some essential elements (N, P, and Fe) biologically available for plants and producing growth regulators that promote plant growth and fitness. Therefore, light directly or indirectly influences plantmicrobe interactions. The usage of light-emitting diodes in plant growth facilities is helping increasing knowledge in the field. This progress will help define light recipes to optimize outputs on plant-phyllosphere communications. This review describes research advancements on light-regulated plant-phyllosphere interactions. The effects of full light spectra and narrow bandwidth-wavelengths from UV to far-red light are discussed.

Narrow-bandwidth light treatments may be used to manipulate plant growth, development and metabolism. In this report LED-based light treatments were used to affect yield and metabolic content of sweet basil (Ocimum basilicum L. cv “Ceasar”) grown in controlled environments. This culinary herb produces an aroma highly appreciated by consumers, primarily composed of terpenes/terpenoids, phenylpropanoids, and fatty-acid- derived volatile molecules. Basil plants were grown under narrow-bandwidth light conditions, and leaf area, height, mass, antioxidant capacity and volatile emissions were measured at various time points. The results indicate reproducible significant differences in specific volatiles, and in biochemical classes of volatiles, compared to greenhouse grown plants. For example, basil plants grown under blue/red/yellow or blue/red/green wavelengths emit higher levels of a subset of monoterpenoid volatiles, while a blue/red/far-red treatment leads to higher levels of most sesquiterpenoid volatile molecules. Specific light treatments increase volatile content, mass, and antioxidant capacity. The results show that narrow-bandwidth illumination can induce discrete suites of volatile classes that affect sensory quality in commercial herbs, and may be a useful tool in improving commercial production.

Agrobacterium-infiltration (agroinfiltration) transient expression systems facilitate rapid primary characterization of candidate gene function, protein localization, protein interacting partners, or other information from a delivered construct. Most of these characterizations have been performed in Nicotiana benthamiana leaves, which offer a limited set of cell types, metabolites, and developmental plasticity. As efforts to characterize genes associated with fruit and vegetable quality increase, the strawberry fruit has emerged as a useful tool to study the effects of transient gene expression. Introduction of active Agrobacterium cultures bearing loss- or gain-of-function constructs into developing fruits can provide robust gene silencing or modest overexpression within days of treatment. Fruits can then be assessed for transgene effects on endogenous gene expression, metabolism, physiology or development. The approach also allows introduction of VIGS-mediated silencing constructs as well as the assessment of promoter activity in fruits. This review details how the strawberry agroinfiltration system has been used as an efficient system to characterize an increasing number of genes associated with fruit development, physiology and metabolism.

Block of cell proliferation (BOP) proteins are conserved among eukaryotes, and studies in mammals and yeast have described their role in ribosome biogenesis and cell cycle regulation. A BOP1 orthologue was identified in plants, and loss-of-function analyses in tobacco cells confirmed similar activities. This report characterizes a role for BOP1 activity in planta. Two transgenic plant species were used: the diploid strawberry (Fragaria vesca) and Arabidopsis thaliana. FvBOP1 silencing showed changes in pre-rRNA processing, and demonstrated FvBOP1's role in growth and physiology throughout different stages of plant development. In the strawberry, repression of FvBOP1 activity decreased plant fitness prior to flowering, followed by plant death after the reproductive transition, indicating that BOP1 activity is required for transition back to vegetative growth after flowering. A T-DNA null allele of the AtBOP1 gene is lethal, and a 50% decrease in transcript accumulation is sufficient to cause severe developmental defects linked to defective cell division. The conserved protein BOP1 is essential for viability. Lower transcript levels result in defects in rRNA processing and developmental abnormalities that are consistent with its predicted role in ribosome biogenesis.

Modern horticultural lighting systems are implementing solid-state light sources as a supplement or alternative to sunlight or other artificial lighting systems. Many lighting systems, including those with light emitting diodes, typically ignore the contributions of green wavebands in plant development, and ultimately may affect the potential value of horticultural products produced under them. It has been shown that green light can reverse anthocyanin accumulation in Arabidopsis thaliana. The goal of this work is to test the hypothesis that green wavebands can modulate the accumulation of these valued pigments in three varieties of microgreen seedlings. The results show that while anthocyanins are induced with far-red light, green light cannot reverse, and may enhance, their accumulation under low-fluence-rate conditions, but the trend reverses in some seedlings under high-fluence rate conditions. On the other hand, blue-light-induced anthocyanin accumulation may be inhibited by the addition of green wavebands, and the effect is fluence-rate dependent and varies in sensitivity and amplitude, depending on the genotype. These trials underscore the importance of considering the inhibitory effects of green light on anthocyanin accumulation when designing lighting systems.

Plant productivity and product quality ultimately are dependent on an interaction between genetics and environment, and one of the most important environmental cues is light. Light quantity, quality, and duration provide critical information to plants that mediate growth and development. Light signal transduction is dependent on a series of photoreceptors and their associated signaling pathways that direct intracellular processes that lead to changes in gene expression that ultimately affect plant form, function, and content. For the last several decades, scientists have dissected these signaling pathways and understand how they connect the environment to a response. The advent of narrow-bandwidth illumination in commercial lighting invites the opportunity to manipulate plant behavior and productivity through precise alteration of the ambient spectrum. This review describes the biochemical links that convert incident light into predictable changes in plant growth and development. These sensors and pathways serve as biochemical switches that can be selectively toggled to control plant growth, development, physiology, or metabolite accumulation.

Different light wavelengths have specific effects on plant growth and development. Narrow-bandwidth light-emitting diode (LED) lighting may be used to directionally manipulate size, color and metabolites in high-value fruits and vegetables. In this report, Red Russian kale ( Brassica napus ) seedlings were grown under specific light conditions and analyzed for photomorphogenic responses, pigment accumulation and nutraceutical content. The results showed that this genotype responds predictably to darkness, blue and red light, with suppression of hypocotyl elongation, development of pigments and changes in specific metabolites. However, these seedlings were relatively hypersensitive to far-red light, leading to uncharacteristically short hypocotyls and high pigment accumulation, even after growth under very low fluence rates (<1 μmol m −2 s −1 ). General antioxidant levels and aliphatic glucosinolates are elevated by far-red light treatments. Sequential treatments of darkness, blue light, red light and far-red light were applied throughout sprout development to alter final product quality. These results indicate that sequential treatment with narrow-bandwidth light may be used to affect key economically important traits in high-value crops.

Light is a potent regulator of plant growth and development, impacting gene expression to global physiology and metabolism. Plants sense a broad range of wavelengths, from UV to far-red, through separate photoreceptors. These light sensors direct adaptive responses under changing environmental conditions and specifically activate precise downstream signaling pathways. Research studies in photobiology, mostly in Arabidopsis thaliana, have characterized light effects on many plant behaviors, along with the genetic mechanisms that control them. Transferring this knowledge to crops has opened a new field in plant science where variation in light quantity, quality, duration or combinations can be used to change plant growth, development or metabolism to influence a desired final product. With the potential of easily being introduced into production chains, and given its safety and relative low cost, this approach can be combined with, or used as an alternative to, breeding or genetic engineering. We review how light has been used in 22 different crop species to manipulate growth characteristics, nutritional value, and yield. We also discuss future opportunities in using light to control produce quality or timing of plant product production.

The Arabidopsis XBAT35 is one of five structurally related ankyrin repeat-containing Really Interesting New Gene (RING) E3 ligases involved in ubiquitin-mediated protein degradation, which plays key roles in a wide range of cellular processes. Here, we show that the XBAT35 gene undergoes alternative splicing, generating two transcripts that are constitutively expressed in all plant tissues. The two splice variants derive from an exon skipping event that excludes an in-frame segment from the XBAT35 precursor mRNA, giving rise to two protein isoforms that differ solely in the presence of a nuclear localization signal (NLS). Transient expression assays indicate that the isoform lacking the NLS localizes in the cytoplasm of plant cells, whereas the other is targeted to the nucleus, accumulating in nuclear speckles. Both isoforms are functional E3 ligases, as assessed by in vitro ubiquitination assays. Two insertion mutant alleles and RNA-interference (RNAi) silencing lines for XBAT35 display no evident phenotypes under normal growth conditions, but exhibit hypersensitivity to the ethylene precursor 1-aminocyclopropane-1-carboxylate (ACC) during apical hook exaggeration in the dark, which is rescued by an inhibitor of ethylene perception. Independent expression of each XBAT35 splice variant in the mutant background indicates that the two isoforms may differentially contribute to apical hook formation but are both functional in this ethylene-mediated response. Thus, XBAT35 defines a novel player in ethylene signaling involved in negatively regulating apical hook curvature, with alternative splicing controlling dual targeting of this E3 ubiquitin ligase to the nuclear and cytoplasmic compartments.

The plant-specific SR45 belongs to the highly conserved family of serine/arginine-rich (SR) proteins, which play key roles in precursor-mRNA splicing and other aspects of RNA metabolism. An Arabidopsis (Arabidopsis thaliana) loss-of-function mutant, sr45-1, displays pleiotropic phenotypes, such as defects in flower and leaf morphology, root growth, and flowering time. Here, we show that the sr45-1 mutation confers hypersensitivity to glucose (Glc) during early seedling growth in Arabidopsis. Unlike wild-type plants, the sr45-1 mutant displays impaired cotyledon greening and expansion as well as reduced hypocotyl elongation of dark-grown seedlings when grown in the presence of low (3%) Glc concentrations. In addition, SR45 is involved in the control of Glc-responsive gene expression, as the mutant displays enhanced repression of photosynthetic and nitrogen metabolism genes and overinduction of starch and anthocyanin biosynthesis genes. Like many other sugar response mutants, sr45-1 also shows hypersensitivity to abscisic acid (ABA) but appears to be unaffected in ethylene signaling. Importantly, the sr45-1 mutant shows enhanced ability to accumulate ABA in response to Glc, and the ABA biosynthesis inhibitor fluridone partially rescues the sugar-mediated growth arrest. Moreover, three ABA biosynthesis genes and two key ABA signaling genes, ABI3 and ABI5, are markedly overinduced by Glc in sr45-1. These results provide evidence that the SR45 protein defines a novel player in plant sugar response that negatively regulates Glc signaling during early seedling development by down-regulating both Glc-specific ABA accumulation and ABA biosynthesis and signaling gene expression.