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Precise control of plant stem cell proliferation is necessary for the continuous and reproducible development of plant organs 1 , 2 . The peptide ligand CLAVATA3 (CLV3) and its receptor protein kinase CLAVATA1 (CLV1) maintain stem cell homeostasis within a deeply conserved negative feedback circuit 1 , 2 . In Arabidopsis , CLV1 paralogs also contribute to homeostasis, by compensating for the loss of CLV1 through transcriptional upregulation 3 . Here, we show that compensation 4 , 5 operates in diverse lineages for both ligands and receptors, but while the core CLV signaling module is conserved, compensation mechanisms have diversified. Transcriptional compensation between ligand paralogs operates in tomato, facilitated by an ancient gene duplication that impacted the domestication of fruit size. In contrast, we found little evidence for transcriptional compensation between ligands in Arabidopsis and maize, and receptor compensation differs between tomato and Arabidopsis . Our findings show that compensation among ligand and receptor paralogs is critical for stem cell homeostasis, but that diverse genetic mechanisms buffer conserved developmental programs. A study of a stem cell receptor–ligand signaling module across tomato, maize and Arabidopsis identifies different genetic mechanisms of compensation that contribute to homeostasis.

The shape of a plant is largely determined by regulation of lateral branching. Branching architecture can vary widely in response to both genotype and environment, suggesting regulation by a complex interaction of autonomous genetic factors and external signals. Tillers, branches initiated at the base of grass plants, are suppressed in response to shade conditions. This suppression of tiller and lateral branch growth is an important trait selected by early agriculturalists during maize domestication and crop improvement. To understand how plants integrate external environmental cues with endogenous signals to control their architecture, we have begun a functional characterization of the maize mutant grassy tillers1 (gt1). We isolated the gt1 gene using positional cloning and found that it encodes a class I homeodomain leucine zipper gene that promotes lateral bud dormancy and suppresses elongation of lateral ear branches. The gt1 expression is induced by shading and is dependent on the activity of teosinte branched1 (tb1), a major domestication locus controlling tillering and lateral branching. Interestingly, like tb1, gt1 maps to a quantitative trait locus that regulates tillering and lateral branching in maize and shows evidence of selection during maize domestication. Branching and shade avoidance are both of critical agronomic importance, but little is known about how these processes are integrated. Our results indicate that gt1 mediates the reduced branching associated with the shade avoidance response in the grasses. Furthermore, selection at the gt1 locus suggests that it was involved in improving plant architecture during the domestication of maize.

GPRC6A is a widely expressed orphan G-protein coupled receptor that senses extracellular amino acids, osteocalcin and divalent cations in vitro. The physiological functions of GPRC6A are unknown. In this study, we created and characterized the phenotype of GPRC6A(-/-) mice. We observed complex metabolic abnormalities in GPRC6A(-/-) mice involving multiple organ systems that express GPRC6A, including bone, kidney, testes, and liver. GPRC6A(-/-) mice exhibited hepatic steatosis, hyperglycemia, glucose intolerance, and insulin resistance. In addition, we observed high expression of GPRC6A in Leydig cells in the testis. Ablation of GPRC6A resulted in feminization of male GPRC6A(-/-) mice in association with decreased lean body mass, increased fat mass, increased circulating levels of estradiol, and reduced levels of testosterone. GPRC6A was also highly expressed in kidney proximal and distal tubules, and GPRC6A(-/-) mice exhibited increments in urine Ca/Cr and PO(4)/Cr ratios as well as low molecular weight proteinuria. Finally, GPRC6A(-/-) mice exhibited a decrease in bone mineral density (BMD) in association with impaired mineralization of bone. GPRC6A(-/-) mice have a metabolic syndrome characterized by defective osteoblast-mediated bone mineralization, abnormal renal handling of calcium and phosphorus, fatty liver, glucose intolerance and disordered steroidogenesis. These findings suggest the overall function of GPRC6A may be to coordinate the anabolic responses of multiple tissues through the sensing of extracellular amino acids, osteocalcin and divalent cations.

Suppression of inflorescence leaf, or bract, growth has evolved multiple times in diverse angiosperm lineages, including the Poaceae and Brassicaceae. Studies of Arabidopsis thaliana mutants have revealed several genes involved in bract suppression, but it is not known if these genes play a similar role in other plants with suppressed bracts. We identified maize (Zea mays) tassel sheath (tsh) mutants, characterized by the loss of bract suppression, that comprise five loci (tsh1-tsh5). We used map-based cloning to identify Tsh1 and found that it encodes a GATA zinc-finger protein, a close homolog of HANABA TARANU (HAN) of ARABIDOPSIS: The bract suppression function of Tsh1 is conserved throughout the grass family, as we demonstrate that the rice (Oryza sativa) NECK LEAF1 (NL1) and barley (Hordeum vulgare) THIRD OUTER GLUME (TRD) genes are orthologous with Tsh1. Interestingly, NL1/Tsh1/TRD expression and function are not conserved with HAN. The existence of paralogous NL1/Tsh1/TRD-like genes in the grasses indicates that the NL1/Tsh1/TRD lineage was created by recent duplications that may have facilitated its neofunctionalization. A comparison with the Arabidopsis genes regulating bract suppression further supports the hypothesis that the convergent evolution of bract suppression in the Poaceae involved recruitment of a distinct genetic pathway.

Like all organisms, plants require energy for growth. They achieve this by absorbing light and fixing it into a usable, chemical form via photosynthesis. The resulting carbohydrate (sugar) energy is then utilized as substrates for growth, or stored as reserves. It is therefore not surprising that modulation of carbohydrate metabolism can have profound effects on plant growth, particularly cell division and expansion. However, recent studies on mutants such asstimpyorramosa3have also suggested that sugars can act as signalling molecules that control distinct aspects of plant development. This review will focus on these more specific roles of sugars in development, and will concentrate on two major areas: (i) cross-talk between sugar and hormonal signalling; and (ii) potential direct developmental effects of sugars. In the latter, developmental mutant phenotypes that are modulated by sugars as well as a putative role for trehalose-6-phosphate in inflorescence development are discussed. Because plant growth and development are plastic, and are greatly affected by environmental and nutritional conditions, the distinction between purely metabolic and specific developmental effects is somewhat blurred, but the focus will be on clear examples where sugar-related processes or molecules have been linked to known developmental mechanisms.

Plant transformation has enabled fundamental insights into plant biology and revolutionized commercial agriculture. Unfortunately, for most crops, transformation and regeneration remain arduous even after more than 30 years of technological advances. Genome editing provides novel opportunities to enhance crop productivity but relies on genetic transformation and plant regeneration, which are bottlenecks in the process. Here, we review the state of plant transformation and point to innovations needed to enable genome editing in crops. Plant tissue culture methods need optimization and simplification for efficiency and minimization of time in culture. Currently, specialized facilities exist for crop transformation. Single-cell and robotic techniques should be developed for high-throughput genomic screens. Plant genes involved in developmental reprogramming, wound response, and/or homologous recombination should be used to boost the recovery of transformed plants. Engineering universal Agrobacterium tumefaciens strains and recruiting other microbes, such as Ensifer or Rhizobium, could facilitate delivery of DNA and proteins into plant cells. Synthetic biology should be employed for de novo design of transformation systems. Genome editing is a potential game-changer in crop genetics when plant transformation systems are optimized.

MaizeCODE is a project aimed at identifying and analyzing functional elements in the maize genome. In its initial phase, MaizeCODE assayed up to five tissues from four maize strains (B73, NC350, W22, TIL11) by RNA-Seq, Chip-Seq, RAMPAGE, and small RNA sequencing. To facilitate reproducible science and provide both human and machine access to the MaizeCODE data, we enhanced SciApps, a cloud-based portal, for analysis and distribution of both raw data and analysis results. Based on the SciApps workflow platform, we generated new components to support the complete cycle of MaizeCODE data management. These include publicly accessible scientific workflows for the reproducible and shareable analysis of various functional data, a RESTful API for batch processing and distribution of data and metadata, a searchable data page that lists each MaizeCODE experiment as a reproducible workflow, and integrated JBrowse genome browser tracks linked with workflows and metadata. The SciApps portal is a flexible platform that allows the integration of new analysis tools, workflows, and genomic data from multiple projects. Through metadata and a ready-to-compute cloud-based platform, the portal experience improves access to the MaizeCODE data and facilitates its analysis.

Plasmodesmata are intercellular organelles in plants that establish cytoplasmic continuity between neighboring cells. Microinjection studies showed that plasmodesmata facilitate the cell-to-cell transport of a plant-encoded transcription factor, KNOTTED1 (KN1). KN1 can also mediate the selective plasmodesmal trafficking of kn1 sense RNA. The emerging picture of plant development suggests that cell fate is determined at least in part by supracellular controls responding to cellular position as well as lineage. One of the mechanisms that enables the necessary intercellular communication appears to involve transfer of informational molecules (proteins and RNA) through plasmodesmata.

Summary Increasing populations and temperatures are expected to escalate food demands beyond production capacities, and the development of maize lines with better performance under heat stress is desirable. Here, we report that constitutive ectopic expression of a heterologous glutaredoxin S17 from Arabidopsis thaliana (AtGRXS17) can provide thermotolerance in maize through enhanced chaperone activity and modulation of heat stress‐associated gene expression. The thermotolerant maize lines had increased protection against protein damage and yielded a sixfold increase in grain production in comparison to the non‐transgenic counterparts under heat stress field conditions. The maize lines also displayed thermotolerance in the reproductive stages, resulting in improved pollen germination and the higher fidelity of fertilized ovules under heat stress conditions. Our results present a robust and simple strategy for meeting rising yield demands in maize and, possibly, other crop species in a warming global environment.

Purpose To assess the significance of CA-125 regression as a prognostic indicator and predictor of optimal cytoreduction at interval debulking surgery (IDS) in women with ovarian or primary peritoneal carcinoma receiving neoadjuvant chemotherapy (NAC). Methods 63 women treated between 2004 and 2007 with neoadjuvant platinum-based chemotherapy followed by IDS were studied retrospectively. Pre-operative CA-125 values were used to calculate a regression coefficient (CA-125r) using exponential regression analysis. Outcome endpoints were overall survival (OS), time to CA-125 progression (TTC) by Rustin criteria and time to second-line treatment (TTS). Results Women with a CA-125 half-life greater than 18 days had a significantly worse OS compared to those with a half-life less than 12 days on univariate testing (HR 3.34, 95% CI 1.25–8.94, p  = 0.017). On multivariable analysis, CA-125r was an independent predictor of OS [HR 1.18 (per 0.01 increase in CA-125r), 95% CI 1.01–1.40, p  = 0.043]. CA-125r was independently predictive of TTC and TTS (HR 1.17, p  ≈ 0.03 for each). CA-125r was also predictive of achieving optimal cytoreduction at IDS (AUC 0.756, p  < 0.001). Conclusions CA-125 regression rate during pre-operative NAC is of independent prognostic value. CA-125 regression rate strongly predicts for optimal cytoreduction.