Hot off the presses! Apr 01 Trends Plant Sci

The Apr 01 issue of the Trends Plant Sci is now up on Pubget (About Trends Plant Sci): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

• Editorial Board
  - Trends Plant Sci 16(4):i (2011)
  
• Corrigendum: Little evidence for fire-adapted plant traits in Mediterranean climate regions: [S. Don Bradshaw et al. Little evidence for fire-adapted plant traits in Mediterranean climate regions. Trends Plant Sci. 16, 69–76]
  - Trends Plant Sci 16(4):177 (2011)
  
• A framework integrating plant growth with hormones and nutrients
  - Trends Plant Sci 16(4):178-182 (2011)
  It is well known that nutrient availability controls plant development. Moreover, plant development is finely tuned by a myriad of hormonal signals. Thus, it is not surprising to see increasing evidence of coordination between nutritional and hormonal signaling. In this opinion article, we discuss how nitrogen signals control the hormonal status of plants and how hormonal signals interplay with nitrogen nutrition. We further expand the discussion to include other nutrient–hormone pairs. We propose that nutrition and growth are linked by a multi-level, feed-forward cycle that regulates plant growth, development and metabolism via dedicated signaling pathways that mediate nutrient and hormonal regulation. We believe this model will provide a useful concept for past and future research in this field.
• Redefining plant systems biology: from cell to ecosystem
  - Trends Plant Sci 16(4):183-190 (2011)
  Molecular biologists typically restrict systems biology to cellular levels. By contrast, ecologists define biological systems as communities of interacting individuals at different trophic levels that process energy, nutrient and information flows. Modern plant breeding needs to increase agricultural productivity while decreasing the ecological footprint. This requires a holistic systems biology approach that couples different aggregation levels while considering the variables that affect these biological systems from cell to community. The challenge is to generate accurate experimental data that can be used together with modelling concepts and techniques that allow experimentally verifying in silico predictions. The coupling of aggregation levels in plant sciences, termed Integral Quantification of Biological Organization (IQBiO), might enhance our abilities to generate new desired plant phenotypes.
• Nectar: generation, regulation and ecological functions
  - Trends Plant Sci 16(4):191-200 (2011)
  Nectar contains water, sugars and amino acids to attract pollinators and defenders and is protected from nectar robbers and microorganisms by secondary compounds and antimicrobial proteins. Floral and extrafloral nectar secretion can be induced by jasmonic acid, it is often adjusted to consumer identity and consumption rate and depends on invertase activity. Invertases are likely to play at least three roles: the uploading of sucrose from the phloem, carbohydrate mobilization during active secretion and the postsecretory adjustment of the sucrose:hexose ratio of nectar. However, it remains to be studied how plants produce and secrete non-carbohydrate components. More research is needed to understand how plants produce nectar, the most important mediator of their interactions with mutualistic animals.
• Plasmodesmata: the battleground against intruders
  - Trends Plant Sci 16(4):201-210 (2011)
  Plasmodesmata are intercellular channels that establish a symplastic communication pathway between neighboring cells in plants. Owing to this role, opportunistic microbial pathogens have evolved to exploit plasmodesmata as gateways to spread infection from cell to cell within the plant. However, although these pathogens have acquired the capacity to breach the plasmodesmal trafficking pathway, plants are unlikely to relinquish control over a structure essential for their survival so easily. In this review, we examine evidence that suggests plasmodesmata play an active role in plant immunity against viral, fungal and bacterial pathogens. We discuss how these pathogens differ in their lifestyles and infection modes, and present the defense strategies that plants have adopted to prevent the intercellular spread of an infection.
• A few standing for many: embryo receptor-like kinases
  - Trends Plant Sci 16(4):211-217 (2011)
  Development of plant embryos is a complex and highly organized process, and experimental evidence indicates that intercellular signaling plays a major role. The recent identification of Receptor-Like Kinases (RLKs) and related Receptor-Like Cytoplasmic Kinases (RLCKs) with specific roles in Arabidopsis thaliana embryo development suggest important functions of intercellular signaling during embryogenesis. Despite the characterization of only a few RLKs and RLCKs with embryonic roles, expression data indicate that many RLKs and RLCKs with either post-embryonic functions or unknown functions are transcribed in Arabidopsis embryos. The functional characterization of a few members of this large kinase family is likely to represent only the tip of the iceberg, and we predict that many RLKs and RLCKs play major roles throughout embryo development.
• Ancient and essential: the assembly of iron–sulfur clusters in plants
  - Trends Plant Sci 16(4):218-226 (2011)
  In plants iron–sulfur (Fe–S) proteins are found in the plastids, mitochondria, cytosol and nucleus, where they are essential for numerous physiological and developmental processes. Recent mutant studies, mostly in Arabidopsis thaliana, have identified three pathways for the assembly of Fe–S clusters. The plastids harbor the SUF (sulfur mobilization) pathway and operate independently, whereas cluster assembly in the cytosol depends on the emerging CIA (cytosolic iron–sulfur cluster assembly) pathway and mitochondria. The latter organelles use the ISC (iron–sulfur cluster) assembly pathway. In all three pathways the assembly process can be divided into a first stage where S and Fe are combined on a scaffold protein, and a second stage in which the Fe–S cluster is transferred to a target protein. The second stage might involve different carrier proteins with specialized functions.
• Transcriptional networks for lignin biosynthesis: more complex than we thought?
  - Trends Plant Sci 16(4):227-233 (2011)
  Lignin is an aromatic heteropolymer and the second most abundant plant biopolymer after cellulose. It is deposited mostly in the secondary cell walls of vascular plants and is essential for water transport, mechanical support and for plant pathogen defense. Lignin biosynthesis is a highly energy-consuming and irreversible process that responds to many developmental and environmental cues, including light, sugar content, circadian clock, plant hormones and wounding. During the past decade, many transcription factors involved in lignin biosynthesis have been identified and characterized. In this review, we assess how these transcriptional activators and repressors modulate lignin biosynthesis, and discuss crosstalk between the lignin biosynthesis pathway and other physiological processes.