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Smith S.M.,University of Western Australia | Li J.,CAS Institute of Genetics and Developmental Biology
Current Opinion in Plant Biology | Year: 2014

Strigolactone (SL) and karrikin (KAR) signalling control many aspects of plant growth and development through similar mechanisms employing related α/β-fold hydrolase-receptors and a common F-box protein named MORE AXILARY BRANCHES2 (MAX2) in Arabidopsis or DWARF3 (D3) in rice. D3 mediates SL-dependent ubiquitination and proteolysis of DWARF53 (D53) protein, thought to be involved in the control of gene expression, while a related protein SUPPRESSOR OF MAX2-1 (SMAX1) is implicated in the response to KAR in Arabidopsis. Different members of the D53/SMAX1 multigene family likely mediate different responses in plant growth and development. Analysis of responses to SL or KAR has identified many genes regulated by these compounds. Crosstalk with other signalling systems including light, hormones and abiotic stress has also been identified. Here we critically analyse how to progress towards a clearer understanding of the targets and functions of the SL and KAR signalling systems. © 2014 Elsevier Ltd.

Speakman J.R.,CAS Institute of Genetics and Developmental Biology | Speakman J.R.,University of Aberdeen
Annual Review of Nutrition | Year: 2013

The prevalence of obesity in modern societies has two major contributory factors-an environmental change that has happened in historical times and a genetic predisposition that has its origins in our evolutionary history. Understanding both aspects is complex. From an evolutionary perspective, three different types of explanation have been proposed. The first is that obesity was once adaptive and enabled us to survive (or sustain fecundity) through periods of famine. People carrying so-called thrifty genes that enabled the efficient storage of energy as fat between famines would be at a selective advantage. In the modern world, however, people who have inherited these genes deposit fat in preparation for a famine that never comes, and the result is widespread obesity. The key problem with this, and any other adaptive scenario, is to understand why, if obesity was historically so advantageous, many people did not inherit these thrifty genes and in modern society are able to remain slim, despite the environmental change favoring fat storage. The second type of explanation is that obesity is not adaptive and may never even have existed in our evolutionary past, but it is favored today as a maladaptive by-product of positive selection on some other trait. An example of this type of explanation is the suggestion that obesity results from variation in brown adipose tissue thermogenesis. Finally, a third class of explanation is that most mutations in the genes that predispose us to obesity are neutral and have been drifting over evolutionary time-so-called drifty genes, leading some individuals to be obesity prone and others obesity resistant. In this article, I review the current evidence for and against these three different scenarios and conclude that the thrifty gene hypothesis is untenable but the other two ideas may provide a cogent explanation of the modern obesity phenomenon. © 2013 by Annual Reviews. All rights reserved.

Voytas D.F.,University of Minnesota | Gao C.,CAS Institute of Genetics and Developmental Biology
PLoS Biology | Year: 2014

Plant agriculture is poised at a technological inflection point. Recent advances in genome engineering make it possible to precisely alter DNA sequences in living cells, providing unprecedented control over a plant's genetic material. Potential future crops derived through genome engineering include those that better withstand pests, that have enhanced nutritional value, and that are able to grow on marginal lands. In many instances, crops with such traits will be created by altering only a few nucleotides among the billions that comprise plant genomes. As such, and with the appropriate regulatory structures in place, crops created through genome engineering might prove to be more acceptable to the public than plants that carry foreign DNA in their genomes. Public perception and the performance of the engineered crop varieties will determine the extent to which this powerful technology contributes towards securing the world's food supply. © 2014 Voytas, Gao.

Dou D.,Nanjing Agricultural University | Zhou J.-M.,CAS Institute of Genetics and Developmental Biology
Cell Host and Microbe | Year: 2012

Phytopathogenic bacteria, fungi, and oomycetes invade and colonize their host plants through distinct routes. These pathogens secrete diverse groups of effector proteins that aid infection and establishment of different parasitic lifestyles. Despite this diversity, a comparison of different plant-pathogen systems has revealed remarkable similarities in the host immune pathways targeted by effectors from distinct pathogen groups. Immune signaling pathways mediated by pattern recognition receptors, phytohormone homeostasis or signaling, defenses associated with host secretory pathways and pathogen penetrations, and plant cell death represent some of the key processes controlling disease resistance against diverse pathogens. These immune pathways are targeted by effectors that carry a wide range of biochemical functions and are secreted by completely different pathogen groups, suggesting that these pathways are a common battleground encountered by many plant pathogens. © 2012 Elsevier Inc.

Li H.,CAS Institute of Genetics and Developmental Biology
Plant physiology | Year: 2011

We have previously shown that the Arabidopsis (Arabidopsis thaliana) RING-H2 E3 ligase RHA2a positively regulates abscisic acid (ABA) signaling during seed germination and postgerminative growth. Here, we report that RHA2b, the closest homolog of RHA2a, is also an active E3 ligase and plays an important role in ABA signaling. We show that RHA2b expression is induced by ABA and that overexpression of RHA2b leads to ABA-associated phenotypes such as ABA hypersensitivity in seed germination and seedling growth, enhanced stomatal closure, reduced water loss, and, therefore, increased drought tolerance. On the contrary, the rha2b-1 mutant shows ABA-insensitive phenotypes and reduced drought tolerance. We provide evidence showing that a rha2a rha2b-1 double mutant generally enhances ABA insensitivity of rha2b-1 in seed germination, seedling growth, and stomatal closure, suggesting that RHA2b and RHA2a act redundantly in regulating ABA responses. Genetic analyses support that, like RHA2a, the RHA2b action in ABA signaling is downstream of a protein phosphatase 2C, ABA-INSENSITIVE2 (ABI2), and in parallel with that of the ABI transcription factors ABI3/4/5. We speculate that RHA2b and RHA2a may have redundant yet distinguishable functions in the regulation of ABA responses.

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