A gene regulatory network critical for axillary bud dormancy directly controlled by Arabidopsis BRANCHED1

The control of branch outgrowth is critical for plant fitness, stress resilience and crop yield. The Arabidopsis thaliana transcription factor BRANCHED1 (BRC1) plays a pivotal role in this process as it integrates signals that inhibit axillary bud growth to control shoot branching. Despite the remarkable activity of BRC1 as a potent growth inhibitor, the mechanisms by which it promotes and maintains bud dormancy are still largely unknown.Here we combine ChIP-seq, transcriptomic and systems biology approaches to characterise the BRC1-regulated gene network. We identify a group of BRC1 direct target genes encoding transcription factors (BTFs) that orchestrate, together with BRC1, an intricate transcriptional network enriched in abscisic acid signalling components. The BRC1 network is enriched in feed-forward loops and feed-back loops, robust against noise and mutation, reversible in response to stimuli, and stable once established. This knowledge is fundamental to adapt plant architecture and crop production to ever-changing environmental conditions.

A screening system using minimal media identifies a flavin-competing inhibitor of Porphyromonas gingivalis growth

ABSTRACT Chronic periodontitis is caused by dysbiosis of human oral commensals and especially by increase in Porphyromonas gingivalis. Inhibitors of P. gingivalis growth are expected to serve as effective drugs for the periodontal therapy. In the present study, we isolated new growth inhibitors of P. gingivalis using minimal media for P. gingivalis. The minimal media included the previously reported Globulin–Albumin (GA) and the newly developed Lactalbumin-Ferric chloride (LF) and Globulin-Calcium chloride (GC); all supported growth of the wild-type strain of P. gingivalis but did not support the growth of a mutant defective for a type IX secretion system. GC contains CaCl2, indicating that P. gingivalis requires a calcium ion for growth. Using LF and GA, we screened about 100 000 compounds and identified 73 that strongly inhibited the growth of P. gingivalis. More than half of these candidates would not have been obtained if these minimal media had not been used in our screen. One of our candidate inhibitors was diphenyleneiodonium chloride (DPIC), which showed strong bactericidal activity against P. gingivalis. Excess amounts of flavin adenine dinucleotide or flavin mononucleotide suppressed the inhibitory activity of DPIC, suggesting that DPIC would be a novel potent growth inhibitor.

A light-dependent molecular link between competition cues and defense responses in plants

ABSTRACTOne of the principal internal signals controlling plant growth and defense is jasmonate (JA), a potent growth inhibitor that is simultaneously a central regulator of plant immunity to herbivores and pathogens. When shade-intolerant plants perceive the proximity of competitors using the photoreceptor phytochrome B (phyB), they accelerate growth and down-regulate JA responses. However, the mechanisms by which photoreceptors relay light cues to the JA signaling pathway are not understood. Here we identify a sulfotransferase (ST2a) that is strongly up-regulated by plant proximity perceived by phyB via the phyB-Phytochrome Interacting Factor (PIF) signaling module. By catalyzing the formation of a sulfated JA derivative, ST2a acts to degrade bioactive forms of JA and represents a direct molecular link between photoreceptors and hormone signaling in plants. The enzyme provides a molecular mechanism for prioritizing shade avoidance over defense under close plant competition.

Triflumuron Effects on the Physiology and Reproduction ofRhodnius prolixusAdult Females

We evaluated the efficacy of the growth regulator triflumuron (TFM) in inducing mortality and disrupting both oviposition and egg hatching inRhodnius prolixusadult females. TFM was administered via feeding, topically or by continuous contact with impregnated surfaces. Feeding resulted in mild biological effects compared with topical and impregnated surfaces. One day after treatment, the highest mortality levels were observed with topical surface and 30 days later both topical and impregnated surfaces induced higher mortalities than feeding. Oral treatment inhibited oviposition even at lower doses, and hatching of eggs deposited by treated females was similarly affected by the three delivery modes. Topical treatment of eggs deposited by nontreated females significantly reduced hatching. However, treatment per contact of eggs oviposited by untreated females did not disrupt eclosion. Additionally, oral treatment increased the number of immature oocytes per female, and topical treatment reduced the mean size of oocytes. TFM also affected carcass chitin content, diuresis, and innate immunity of treated insects. These results suggest that TFM acts as a potent growth inhibitor ofR. prolixusadult females and has the potential to be used in integrated vector control programs against hematophagous triatomine species.

Electrodegradation of Root Exudates to Mitigate Autotoxicity in Hydroponically Grown Strawberry (Fragaria ×ananassa Duch.) Plants

Root exudates from strawberry plants are known to cause autotoxicity and benzoic acid (BA), a potent growth inhibitor, was found in the exudate. BA (400 μm) was easily decomposed by electrodegradation (ED) treatment at 10.0 V and 2.0 A after the addition of BA into nutrient solution. The growth of strawberry plantlets in nutrient solution containing BA (400 μm) or in control nutrient solution varied significantly depending on the use of ED treatment. The growth inhibition of plantlets in the BA-containing nutrient solution or in nutrient solution used for strawberry culture was significantly ameliorated by ED treatment. This growth recovery resulting from ED treatment was most pronounced in terms of the yield of strawberry fruit. These results suggest that ED treatment of the culture nutrient solution could result in the decomposition of toxic root exudates, including BA from strawberry plants, and mitigates the autotoxicity observed in closed hydroponic culture. In addition, the supplementation of Fe-EDTA is recommended after ED treatment as a result of the rapid decomposition of Fe-EDTA by ED.