Aeroponic approach for nondestructive root exudate collection and simulation of variable water stress trialed on cotton (Gossypium hirsutum).

Analyzing root exudates during drought poses a serious challenge; sampling root exudates in soil is destructive to roots and leads to biased molecular analysis, along with microbial decomposition and exudate sorption to soil components. Hydroponic approaches are useful to overcome these problems but lack the utility to induce drought. Nondestructive sampling techniques are thus needed to analyze root exudates from the same plants over time in combination with highly controlled variable water/nutrient stress.

Mechanical stimulation reprograms the sorghum internode transcriptome and broadly alters hormone homeostasis.

Stem structural failure, or lodging, affects many crops including sorghum, and can cause large yield losses. Lodging is typically caused by mechanical forces associated with severe weather like high winds, but exposure to sub-catastrophic forces may strengthen stems and improve lodging resistance. The responses of sorghum internodes at different developmental stages were examined at 2 and 26 h after initiating moderate mechanical stimulation with an automated apparatus.

Thigmostimulation alters anatomical and biomechanical properties of bioenergy sorghum stems.

Sorghum [Sorghum bicolor (L.) Moench] is a tropical grass that can be used as a bioenergy crop but commonly suffers from stem structural failure (lodging) when exposed to mechanical stimuli, such as rain and wind. Mechanical stimulation can trigger adaptive growth in plant stems (thigmomorphogenesis) by activating regulatory networks of hormones, proteins, transcription factors, and targeted genes, which ultimately alters their physiology, morphology, and biomechanical properties.

Increased Expression of UMAMIT Amino Acid Transporters Results in Activation of Salicylic Acid Dependent Stress Response.

In addition to their role in the biosynthesis of important molecules such as proteins and specialized metabolites, amino acids are known to function as signaling molecules through various pathways to report nitrogen status and trigger appropriate metabolic and cellular responses. Moreover, changes in amino acid levels through altered amino acid transporter activities trigger plant immune responses. Specifically, loss of function of major amino acid transporter, over-expression of cationic amino acid transporter, or over-expression of the positive regulators of membrane amino acid export all lead to dwarfed phenotypes and upregulated salicylic acid (SA)-induced stress marker genes.

A nonproteinaceous Fusarium cell wall extract triggers receptor-like protein-dependent immune responses in Arabidopsis and cotton.

Fusarium wilt caused by the ascomycete fungus Fusarium oxysporum is a devastating disease of many economically important crops. The mechanisms underlying plant responses to F. oxysporum infections remain largely unknown.

Phytochrome interacting factors 4 and 5 regulate axillary branching via bud abscisic acid and stem auxin signalling.

The ratio of red light to far-red light (R:FR) is perceived by phytochrome B (phyB) and informs plants of nearby competition. A low R:FR indicative of competition induces the shade avoidance syndrome and suppresses branching by incompletely understood mechanisms. Phytochrome interacting factors (PIFs) are transcription factors targeted by phytochromes to evoke photomorphogenic responses.

Time-dependent mechanical behavior of sweet sorghum stems.

Grasses represent the most productive and widely grown crop family across the globe but are susceptible to structural failure (lodging) during growth (e.g., from wind).

Rewiring of auxin signaling under persistent shade.

Light cues from neighboring vegetation rapidly initiate plant shade-avoidance responses. Despite our detailed knowledge of the early steps of this response, the molecular events under prolonged shade are largely unclear. Here we show that persistent neighbor cues reinforce growth responses in addition to promoting auxin-responsive gene expression in and soybean.

Silencing Arabidopsis CARBOXYL-TERMINAL DOMAIN PHOSPHATASE-LIKE 4 induces cytokinin-oversensitive de novo shoot organogenesis.

De novo shoot organogenesis (DNSO) is a post-embryonic development programme that has been widely exploited by plant biotechnology. DNSO is a hormonally regulated process in which auxin and cytokinin (CK) coordinate suites of genes encoding transcription factors, general transcription factors, and RNA metabolism machinery. Here we report that silencing Arabidopsis thaliana carboxyl-terminal domain (CTD) phosphatase-like 4 (CPL4 ) resulted in increased phosphorylation levels of RNA polymerase II (pol II) CTD and altered lateral root development and DNSO efficiency of the host plants.

The ratio of red light to far red light alters Arabidopsis axillary bud growth and abscisic acid signalling before stem auxin changes.

Arabidopsis thaliana shoot branching is inhibited by a low red light to far red light ratio (R:FR, an indicator of competition), and by loss of phytochrome B function. Prior studies have shown that phytochrome B deficiency suppresses bud growth by elevating systemic auxin signalling, and that increasing the R:FR promotes the growth of buds suppressed by low R:FR by inhibiting bud abscisic acid (ABA) accumulation and signalling. Here, systemic auxin signalling and bud ABA signalling were examined in the context of rapid bud responses to an increased R:FR.

Convergence of CONSTITUTIVE PHOTOMORPHOGENESIS 1 and PHYTOCHROME INTERACTING FACTOR signalling during shade avoidance.

Shade-avoidance responses require CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) but the mechanisms of action of COP1 under shade have not been elucidated. Using simulated shade and control conditions, we analysed: the transcriptome and the auxin levels of cop1 and phytochrome interacting factor 1 (pif1) pif3 pif4 pif5 (pifq) mutants; the dynamics of ELONGATED HYPOCOTYL 5 (HY5) and LONG HYPOCOTYL IN FAR-RED (HFR1) proteins; and the epistatic relationships between cop1 and pif3, pif4, pif5, hy5 and hfr1 mutations in Arabidopsis thaliana. Despite severely impaired shade-avoidance responses, only a few genes that responded to shade in the wild-type failed to do so in cop1.

Abscisic Acid Is a General Negative Regulator of Arabidopsis Axillary Bud Growth.

Branching is an important process controlled by intrinsic programs and by environmental signals transduced by a variety of plant hormones. Abscisic acid (ABA) was previously shown to mediate Arabidopsis (Arabidopsis thaliana) branching responses to the ratio of red light (R) to far-red light (FR; an indicator of competition) by suppressing bud outgrowth from lower rosette positions under low R:FR. However, the role of ABA in regulating branching more generally was not investigated.

The dominant negative ARM domain uncovers multiple functions of PUB13 in Arabidopsis immunity, flowering, and senescence.

Regulating the intensity and duration of immune responses is crucial to combat infections without deleterious side effects. Arabidopsis FLS2, the receptor for bacterial flagellin, activates immune signalling by association with its partner BAK1. Upon flagellin (flg22) perception, the plant U-box E3 ubiquitin ligases PUB12 and PUB13 complex with FLS2 in a BAK1-dependent manner, and ubiquitinate FLS2 for protein degradation, thereby down-regulating flagellin signalling.

Physiology and transcriptomics of water-deficit stress responses in wheat cultivars TAM 111 and TAM 112.

Hard red winter wheat crops on the U.S. Southern Great Plains often experience moderate to severe drought stress, especially during the grain filling stage, resulting in significant yield losses.

BOTRYTIS-INDUCED KINASE1 Modulates Arabidopsis Resistance to Green Peach Aphids via PHYTOALEXIN DEFICIENT4.

BOTRYTIS-INDUCED KINASE1 (BIK1) plays important roles in induced defense against fungal and bacterial pathogens in Arabidopsis (Arabidopsis thaliana). Its tomato (Solanum lycopersicum) homolog is required for host plant resistance to a chewing insect herbivore. However, it remains unknown whether BIK1 functions in plant defense against aphids, a group of insects with a specialized phloem sap-feeding style.

The timing of low R:FR exposure profoundly affects Arabidopsis branching responses.

The ratio of Red to Far Red light (R:FR) is sensed by phytochromes, including phytochrome B, and serves as a signal of potential competition. Low R:FR represses Arabidopsis thaliana branching by promoting the accumulation of abscisic acid in the young buds and by enhancing auxin signaling in the main shoot. While overall plant level branching is reduced by low R:FR, the growth of the uppermost branches tends to be promoted while the lower buds are suppressed.

Phytochrome B promotes branching in Arabidopsis by suppressing auxin signaling.

Many plants respond to competition signals generated by neighbors by evoking the shade avoidance syndrome, including increased main stem elongation and reduced branching. Vegetation-induced reduction in the red light:far-red light ratio provides a competition signal sensed by phytochromes. Plants deficient in phytochrome B (phyB) exhibit a constitutive shade avoidance syndrome including reduced branching.

Abscisic acid regulates axillary bud outgrowth responses to the ratio of red to far-red light.

Low red light/far-red light ratio (R:FR) serves as an indicator of impending competition and has been demonstrated to suppress branch development. The regulation of Arabidopsis (Arabidopsis thaliana) rosette bud outgrowth by the R:FR and the associated mechanisms were investigated at several levels. Growth under low R:FR suppressed outgrowth of the third from topmost bud (bud n-2) but not that of the topmost bud.

Stem transcriptome reveals mechanisms to reduce the energetic cost of shade-avoidance responses in tomato.

While the most conspicuous response to low red/far-red ratios (R:FR) of shade light perceived by phytochrome is the promotion of stem growth, additional, less obvious effects may be discovered by studying changes in the stem transcriptome. Here, we report rapid and reversible stem transcriptome responses to R:FR in tomato (Solanum lycopersicum). As expected, low R:FR promoted the expression of growth-related genes, including those involved in the metabolism of cell wall carbohydrates and in auxin responses.

Photosynthetic photon flux density and phytochrome B interact to regulate branching in Arabidopsis.

Branching is regulated by environmental signals including phytochrome B (phyB)-mediated responses to the ratio of red to far red light. While the mechanisms associated with phytochrome regulation of branching are beginning to be elucidated, there is little information regarding other light signals, including photosynthetic photon flux density (PPFD) and how it influences phytochrome-mediated responses. This study shows that Arabidopsis (Arabidopsis thaliana) branching is modified by both varying PPFD and phyB status and that significant interactions occur between these variables.

Vegetative axillary bud dormancy induced by shade and defoliation signals in the grasses.

Vegetative axillary bud dormancy and outgrowth is regulated by several hormonal and environmental signals. In perennials, the dormancy induced by hormonal and environmental signals has been categorized as eco-, endo- or paradormancy. Over the past several decades para-dormancy has primarily been investigated in eudicot annuals.

Phytochrome regulation of branching in Arabidopsis.

The red light:far-red light ratio perceived by phytochromes controls plastic traits of plant architecture, including branching. Despite the significance of branching for plant fitness and productivity, there is little quantitative and mechanistic information concerning phytochrome control of branching responses in Arabidopsis (Arabidopsis thaliana). Here, we show that in Arabidopsis, the negative effects of the phytochrome B mutation and of low red light:far-red light ratio on branching were largely due to reduced bud outgrowth capacity and an increased degree of correlative inhibition acting on the buds rather than due to a reduced number of leaves and buds available for branching.

Suppression of sorghum axillary bud outgrowth by shade, phyB and defoliation signalling pathways.

In recent years, several genetic components of vegetative axillary bud development have been defined in both monocots and eudicots, but our understanding of environmental inputs on branching remains limited. Recent work in sorghum (Sorghum bicolor) has revealed a role for phytochrome B (phyB) in the control of axillary bud outgrowth through the regulation of Teosinte Branched1 (TB1) gene. In maize (Zea mays), TB1 is a dosage-dependent inhibitor of axillary meristem progression, and the expression level of TB1 is a sensitive measure of axillary branch development.