Plant Signaling & Behavior

Pavlovič, Andrej

doi: 10.4161/psb.5.11.11906pmid: 20523127

Carnivorous plants have evolved modified leaves into the traps which assist in nutrient uptake from captured prey. It is known that the traps of carnivorous plants have usually lower photosynthetic rates than assimilation leaves as a result of adaptation to carnivory. However a few recent studies have indicated that photosynthesis and respiration undergo spatio-temporal changes during prey capture and retention, especially in the genera with active trapping mechanisms. This study describes the spatio-temporal changes of effective quantum yield of photochemical energy conversion in photosystem II (ФPSII) in response to ant-derived formic acid during its capture and digestion.

Zwenger, Sam R.; Alsaggaf, Rotana; Basu, Chhandak

doi: 10.4161/psb.5.11.12837pmid: 20935479

Weeds play an important role in agriculture and molecular techniques are useful to help understand traits that contribute to weediness and weeds’ interactions with the environment. A total of 377 expressed sequence tags (ESTs) from a modest library were arranged into 227 unique fragments and 61 contigs, which consisted of two or more ESTs. From blastx results, we mapped and annotated unigenes using the gene ontology vocabulary according to biological process, cellular component and molecular function. These were then compared to a reference set of Arabidopsis thaliana sequences for statistically significant over- or underrepresented genes. The sequences were also compared against multiple protein databases for similarity of functional domains. Overall, the S. iberica sequences showed high similarity to response to stress, which included salt-induced proteins, betaine aldehydehyde dehydrogenase and calcium binding proteins. Only a modest number of transcripts were sequenced; however, the results presented here demonstrate the metabolic versatility of S. iberica in sub-optimal conditions that are likely to contribute to its cosmopolitan distribution. Here we propose that an EST library of an economically important weed species could be used to understand the weed’s interactions with the environment.

Kokkirala, Venugopal Rao ; Yonggang, Peng ; Abbagani, Sadanandam ; Zhu, Zhen ; Umate, Pavan

doi: 10.4161/psb.5.11.13318pmid: 21045556

The cellular localization and molecular interactions are indicative of functions of a protein. The development of a simple and efficient method for subcellular localization of a protein is indispensable to elucidate gene function in plants. In this study, we assessed the feasibility of Agrobacterium-mediated transformation (agroinfiltration) of tobacco and tomato leaf tissue to follow intracellular targeting of proteins from rice fused to green fluorescent protein (GFP). For this, a simple in planta assay for subcellular localization of rice proteins in the heterologous host systems of tobacco and tomato leaf via transient transformation was developed. We have tested the applicability of this method by expressing GFP fusions of the putative antiphagocytic protein 1 (APP1) (OsAPP, LOC_Os03g56930) and ZOS3-18 – C2H2 zinc-finger protein (OsZF1, LOC_Os03g55540) from Oryza sativa L. subsp. japonica in tobacco and tomato leaf tissues. Our results demonstrate the suitability of GFP as a reporter in gene expression studies in tomato cv MicroTom. The use of GFP-fused proteins from rice for subcellular targeting in the heterologous hosts of tobacco and tomato plant systems has been confirmed.

Bedinger, Patricia A. ; Pearce, Gregory; Covey, Paul A.

doi: 10.4161/psb.5.11.12954pmid: 21045555

Peptide signaling regulates a variety of developmental processes and environmental responses in plants.1-6 For example, the peptide systemin induces the systemic defense response in tomato7 and defensins are small cysteine-rich proteins that are involved in the innate immune system of plants.8,9 The CLAVATA3 peptide regulates meristem size 10 and the SCR peptide is the pollen self-incompatibility recognition factor in the Brassicaceae 11, 12. LURE peptides produced by synergid cells attract pollen tubes to the embryo sac.9 RALFs are a recently discovered family of plant peptides that play a role in plant cell growth.

Diatloff, Eugene; Peyronnet , Rémi; Colcombet , Jean; Thomine , Sébastien; Barbier-Brygoo, Hélène; Frachisse, Jean-Marie

doi: 10.4161/psb.5.11.12921pmid: 21051946

Plant genomes code for channels involved in the transport of cations, anions and uncharged molecules through membranes. Although the molecular identity of channels for cations and uncharged molecules has progressed rapidly in the recent years, the molecular identity of anion channels has lagged behind. Electrophysiological studies have identified S-type (slow) and R-type (rapid) anion channels. In this brief review, we summarize the proposed functions of the R-type anion channels which, like the S-type, were first characterized by electrophysiology over 20 years ago, but unlike the S-type, have still yet to be cloned. We show that the R-type channel can play multiple roles.

Cox, Murray P. ; Eaton, Carla J. ; Scott, D. Barry

doi: 10.4161/psb.5.11.12950pmid: 21045557

Plant-fungal symbioses are a common feature in nature. They vary from pathogenic interactions, where fungi subvert plant resources for their own use, to mutualistic associations, where both fungus and host benefit from the interaction. Although the ecological importance of plant-fungal symbioses has long been recognized and the biology of several key associations are now well studied, new technologies have the potential to allow fresh insight into the molecular basis of plant-fungal interactions. One such technique – high throughput RNA sequencing – has recently been used to explore the molecular basis of cross-species communications. Here, we give a brief overview of this emerging technology, and present a general guide for employing the methodology to dissect plant-fungal symbiosis.

Galatis, Basil ; Apostolakos, Panagiotis

doi: 10.4161/psb.5.11.12959pmid: 21045558

Callose in polypodiaceous ferns performs multiple roles during stomatal development and function. This highly dynamic (1→3)-β-D-glucan, in cooperation with the cytoskeleton, is involved in: (a) stomatal pore formation, (b) deposition of local GC wall thickenings, and (c) the mechanism of stomatal pore opening and closure. This behavior of callose, among others, probably relies on the particular mechanical properties as well as on the ability to form and degrade rapidly, to create a scaffold or to serve as a matrix for deposition of other cell wall materials, and to produce fibrillar deposits in the periclinal GC walls, radially arranged around the stomatal pore. The local callose deposition in closing stomata is an immediate response of the external periclinal GC walls experiencing strong mechanical forces induced by the neighboring cells. The radial callose fibrils transiently co-exist with radial cellulose microfibrils and, like the latter, seem to be oriented via cortical MTs.

Harris, Jeanne M. ; Dickstein, Rebecca

doi: 10.4161/psb.5.11.13165pmid: 21045559

The Medicago truncatula LATD/NIP gene is essential for the development of lateral and primary root and nitrogen-fixing nodule meristems as well as for rhizobial invasion of nodules. LATD/NIP encodes a member of the NRT1(PTR1) nitrate and di-and tri-peptide transporter family, suggesting that its function is to transport one of these or another compound(s). Because latd/nip mutants can have their lateral and primary root defects rescued by ABA, ABA is a potential substrate for transport. LATD/NIP expression in the root meristem was demonstrated to be regulated by auxin, cytokinin and abscisic acid, but not by nitrate. LATD/NIP’s potential function and its role in coordinating root architecture and nodule formation are discussed.

Taj, Gohar ; Agarwal, Payal ; Grant, Murray ; Kumar, Anil

doi: 10.4161/psb.5.11.13020pmid: 20980831

The mitogen-activated protein kinase (MAPK) cascades play diverse roles in intra- and extra-cellular signaling in plants. MAP kinases are the component of kinase modules which transfer information from sensors to responses in eukaryotes including plants. They play a pivotal role in transduction of diverse extracellular stimuli such as biotic and abiotic stresses as well as a range of developmental responses including differentiation, proliferation and death. Several cascades are induced by different biotic and abiotic stress stimuli such as pathogen infections, heavy metal, wounding, high and low temperatures, high salinity, UV radiation, ozone, reactive oxygen species, drought and high or low osmolarity. MAPK signaling has been implicated in biotic stresses and has also been associated with hormonal responses. The cascade is regulated by various mechanisms, including not only transcriptional and translational regulation but through post-transcriptional regulation such as protein-protein interactions. Recent detailed analysis of certain specific MAP kinase pathways have revealed the specificity of the kinases in the cascade, signal transduction patterns, identity of pathway targets and the complexity of the cascade. The latest insights and finding are discussed in this paper in relation to the role of MAPK pathway modules in plant stress signaling.

Kharshiing, Eros V. ; Kumar, G. Pavan ; Sharma, Rameshwar

doi: 10.4161/psb.5.11.13035pmid: 20980815

The growth and development of plants is regulated by several external and internal factors including auxin. Its distribution regulates several developmental processes in plants. Auxin molecules function as mobile signals and are involved in the spatial and temporal coordination of plant morphogenesis and in plant responses to their environment. The intercellular transport of auxin is facilitated by transport proteins and the disruption of polar auxin flow results in various developmental abnormalities. In this review, we discuss the developmental and physiological significance of over-accumulation of PIN1 auxin transport facilitator protein in tomato as seen in the enhanced polar auxin transport pct1-2 mutant.