Plant growth and development are tightly controlled in response to environmental conditions that influence the availability of photosynthetic carbon in the form of sucrose. Trehalose-6-phosphate (T6P), the precursor of trehalose in the biosynthetic pathway, is an important signaling metabolite that is involved in the regulation of plant growth and development in response to carbon availability. In addition to the plant’s own pathway for trehalose synthesis, formation of T6P or trehalose by pathogens can result in the reprogramming of plant metabolism and development. Developmental processes that are regulated by T6P range from embryo development to leaf senescence. Some of these processes are regulated in interaction with phytohormones, such as auxin. A key interacting factor of T6P signaling in response to the environment is the protein kinase sucrose non-fermenting related kinase-1 (SnRK1), whose catalytic activity is inhibited by T6P. SnRK1 is most likely involved in the adjustment of metabolism and growth in response to starvation. The transcription factor bZIP11 has recently been identified as a new player in the T6P/SnRK1 regulatory pathway. By inhibiting SnRK1, T6P promotes biosynthetic reactions. This regulation has important consequences for crop production, for example, in the developing wheat grain and during the growth of potato tubers.

Biofortification of cereals to overcome hidden hunge

More than 60% of the world population suffers from iron deficiency, and over 30% of the global population has zinc deficiency. Micronutrient deficiency leads to compromised health and economic losses and is prevalent in populations depending on non-diversified plant-based diets. Increasing mineral content of staple food crops through biofortification is the most feasible strategy of combating micronutrient malnutrition. Additionally, it will also enhance the agronomic efficiency of crops on mineral poor soils. A multipronged strategy towards enhancing mineral content of cereal grains should involve increased uptake of minerals from soil, enhanced partitioning towards grain and improved sequestration in the edible tissues of grains. At the same time, it is essential to improve mineral absorption in vivo from cereal-based diets. Both conventional and modern breeding approaches and genetic engineering are being employed for biofortification of crop plants. With increased understanding of mineral uptake and transport mechanisms in plants, it is becoming ever more possible to engineer biofortified crop plants with the ultimate goal of overcoming hidden hunger.

Multiple-herbicide resistance (MHR) in black-grass (Alopecurus myosuroides) and annual rye-grass (Lolium rigidum) is a global problem leading to a loss of chemical weed control in cereal crops. Although poorly understood, in common with multiple-drug resistance (MDR) in tumors, MHR is associated with an enhanced ability to detoxify xenobiotics. In humans, MDR is linked to the overexpression of a pi class glutathione transferase (GSTP1), which has both detoxification and signaling functions in promoting drug resistance. In both annual rye-grass and black-grass, MHR was also associated with the increased expression of an evolutionarily distinct plant phi (F) GSTF1 that had a restricted ability to detoxify herbicides. When the black-grass A. myosuroides (Am) AmGSTF1 was expressed in Arabidopsis thaliana, the transgenic plants acquired resistance to multiple herbicides and showed similar changes in their secondary, xenobiotic, and antioxidant metabolism to those determined in MHR weeds. Transcriptome array experiments showed that these changes in biochemistry were not due to changes in gene expression. Rather, AmGSTF1 exerted a direct regulatory control on metabolism that led to an accumulation of protective flavonoids. Further evidence for a key role for this protein in MHR was obtained by showing that the GSTP1- and MDR-inhibiting pharmacophore 4-chloro-7-nitro-benzoxadiazole was also active toward AmGSTF1 and helped restore herbicide control in MHR black-grass. These studies demonstrate a central role for specific GSTFs in MHR in weeds that has parallels with similar roles for unrelated GSTs in MDR in humans and shows their potential as targets for chemical intervention in resistant weed management.

ntercropping System with Combined Application of Azospirillum and Pseudomonas fluorescens Reduces Root Rot Incidence Caused by Rhizoctonia bataticola and Increases Seed Cotton Yield

Root rot caused by Rhizoctonia bataticola is a serious threat in cotton. Field experiments were conducted to study the influences of intercropping system in cotton with inorganic fertilizer and two bioinoculants (Azospirillum and Pseudomonas) on root rot incidence and yield of cotton. The results revealed that among the intercropping systems, cotton intercropping with Sesbania aculeata (1 : 1 ratio) recorded the highest rhizosphere colonization of Pseudomonas fluorescens in the year 2007 and 2008 and the lowest root rot incidence of 1.40, 2.49 and 3.90; 1.02, 2.22 and 5.98% at the vegetative, flowering and maturity stages in the year 2007 and 2008, respectively. From nutrient management practices, integration of Azospirillum and Pseudomonas with 50% recommended dose of NPK recorded the highest rhizosphere colonization of P. fluorescens in both years and the lowest root rot incidence of 1.40, 2.32 and 3.36; 1.07, 2.01 and 5.25% at vegetative, flowering and maturity stages in 2007 and 2008, respectively. Cotton + S. aculeata recorded the maximum number of sympodial branches (23.5 and 20.62/plant in 2007 and 2008, respectively) and the highest seed cotton yield of 2010 and 1894 kg/ha. The highest cotton equivalent yield (CEY) of 2052 and 1895 kg/ha was recorded in cotton + onion system, which was closely followed by cotton + S. aculeata system that had the CEY of 2010 and 1894 kg/ha in 2007 and 2008, respectively. The increased CEY is due to increased cost of onion compared with S. aculeata. Combined application of 100% recommended dose of NPK and bioinoculants recorded the seed cotton yield of 2227 and 1983 kg/ha and CEY of 2460 and 2190 kg/ha in 2007 and 2008, respectively. The lowest root rot incidence and increased yield in cotton + S. aculeata combined with 50% NPK and bioinoculants could be due to synergistic effect among the bioinoculants and S. aculeata.

Using membrane transporters to improve crops for sustainable food production

With the global population predicted to grow by at least 25 per cent by 2050, the need for sustainable production of nutritious foods is critical for human and environmental health. Recent advances show that specialized plant membrane transporters can be used to enhance yields of staple crops, increase nutrient content and increase resistance to key stresses, including salinity, pathogens and aluminium toxicity, which in turn could expand available arable land.

Death of the genome paper

• Department of Biology, Western University, London, ON, Canada

There is a bloated folder on my laptop computer called Limbolandomics, and stuffed inside it are dozens of genome sequences eagerly waiting to be analyzed, written up, and published. I haven’t told the sequences yet, but their chance to shine in the academic spotlight, to have their nucleotides forever inscribed in the annals of scientific literature, even in an obscure journal, may never come. The “genome paper” is dying and could soon be dead.

Not long ago, a folder full of genomes would have been worth its weight in high-impact publications. The formula was simple. Open with a catchy introduction about the organism of interest, emphasizing its broad biological importance and the many questions that its DNA sequence will help answer, then describe the genome in all its glory, using beautiful chromosome maps and dizzying Venn diagrams.

Genome papers have been the bread and butter of evolutionary biologists and geneticists for decades. They’ve been cultivated, packaged, promoted, and used to describe just about every type of DNA molecule imaginable. From the itty-bitty genomes of viruses, plasmids, and organelles to the gargantuan nuclear genomes of plants, animals, and protists, from the oh-so-boring-won’t-reveal-a-darn-thing-about-anything genomes to the super-cool-send-me-to-Nature genomes, you name it, there’s a genome paper for it.

I built my PhD thesis on genome papers, and most of my peers did the same. My first undergraduate research project was to sequence and describe the mitochondrial genome of the giant sea scallop. On top of being a riveting conversation starter at the campus pub, the scallop genome taught me tons about genetics and the publication process. A genome project, when the sequence is manageable, like a mitochondrial DNA, can be an excellent teaching tool. There is a well-defined goal, the methods are generally straightforward and cover a wide range of techniques, from molecular biology to population genetics to bioinformatics, and writing up the data is often enjoyable, and in some ways similar to a character sketch.

One of the drawbacks of genome papers, however, is that they can create a mindset of sequence first, ask questions later. I once attended a Masters thesis defense where the external examiner asked the candidate why he sequenced the chloroplast genome of this particular species and what hypothesis was he trying to test. The student, looking startled, answered, “Because the genome hadn’t been sequenced before and we didn’t know what it looked like.” After the defense, I overheard the examiner in the hallway venting to another professor. “We’ve created a culture of serial genomicists,” she exclaimed. “Everyone’s jumping from one genome sequence to the next, looking to score a major publication.”

…..

Plant biotechnology: Tarnished promise

Genome analyses of the wheat yellow (stripe) rust pathogen Puccinia striiformis f. sp. tritici reveal polymorphic and haustorial expressed secreted proteins as candidate effectors

Wheat yellow (stripe) rust caused by Puccinia striiformis f. sp. tritici (PST) is one of the most devastating diseases of wheat worldwide. To design effective breeding strategies that maximize the potential for durable disease resistance it is important to understand the molecular basis of PST pathogenicity. In particular, the characterisation of the structure, function and evolutionary dynamics of secreted effector proteins that are detected by host immune receptors can help guide and prioritize breeding efforts. However, to date, our knowledge of the effector repertoire of cereal rust pathogens is limited.

History of the invasion of the anther smut pathogen on Silene latifolia in North America

The xylan utilization system of the plant pathogen Xanthomonas campestris pv campestris controls epiphytic life and reveals common features with oligotrophic bacteria and animal gut symbionts