Volume 22, Issue 1, January 2010

This work examines the molecular basis of heterosis by comprehensively describing the epigenetic modifications and transcriptional output, including both mRNA and small RNAs, of two rice subspecies and their reciprocal hybrids.

Make assurance double sure: Two chromatin modifications join forces to create a double lock and need to be removed simultaneously to reactivate a heritable epiallele originating from polyploid Arabidopsis.

This work demonstrates that region-specific interelement recombinational exchange, behind natural selection, plays a primary role in maintaining preexisting partnership and establishing new partnership between nonautonomous and autonomous long terminal repeat retrotransposons in soybean.

This study shows that BOP1 and BOP2 regulate key organogenic events in the proximal region of cotyledon and leaf primordia. Direct activation of AS2 transcription by BOP1 and BOP2 is found to be required for KNOX1 gene repression at the leaf base and may represent a conserved mechanism for coordinating leaf morphogenesis with patterning along the adaxial-abaxial and the proximal-distal axes.

An Arabidopsis plastid triose phosphate isomerase mutant was reduced in transcript, protein, and activity, resulting in a severely stunted plant at the transition from heterotrophic to autotrophic growth. Accumulation of dihydroxyacetone phosphate and methylglyoxal to toxic levels is proposed as a cause of this phenotype, as exogenous application of these metabolites mimicked the phenotype.

This study identifies targets and interacting factors of an Arabidopsis basic helix-loop-helix protein, ABORTED MICROSPORES (AMS), which is known to be required for pollen development. AMS is found to regulate the expression of several genes involved in metabolism and pollen wall deposition.

CUL4-DDB1 associates with COP1-SPA complexes via its linker protein DDB1 to regulate photomorphogenesis and possibly also flowering time under short-day conditions. The CUL4-DDB1-COP1-SPA supercomplex may represent a novel group of E3 ligases that functions independently of the CDD complex.

This study describes the collection of UBL/UBA domain proteins in Arabidopsis that participate in the ubiquitin/26S proteasome system, with a focus on the RAD23 family. The data point to a specific role for RAD23s in plants and suggest that the four isoforms have both redundant and unique roles in Arabidopsis development by helping shuttle ubiquitin conjugates to the 26S proteasome.

This study describes the function of RPL4A, a ribosomal protein. It finds a link between ribosomal biogenesis and vacuolar protein sorting and provides insights into the auxin-mediated regulation of vacuolar trafficking in metabolically active tissues.

This work shows that loss-of-function mutants of retromer large subunit genes ZIP3/VPS35a, VPS29, and VPS26a partially suppressed the defects in morphology and gravitropism of zig mutants. By contrast, mutations of the paralogous genes VPS35b, VPS35c, and VPS26b do not suppress zig. Functional differences among these paralogous genes suggest that VPS35A function differs from that of VPS35B or VPS35C.

This work finds that a fatty acid ω -hydroxylation pathway in rice that relies on an ancient cytochrome P450 subfamily is essential for the formation of both anther cuticle and pollen exine during plant male reproductive and spore development.

This study demonstrates that γ -Tubulin Complex Protein 4 plays a crucial role in γ -tubulin–mediated microtubule nucleation and organization during cell division and morphogenesis in Arabidopsis.

This work uses reverse genetic and biochemical approaches to provide evidence supporting the hypothesis that an Hsp70 system plays a heretofore unrecognized role in chloroplast protein import.

Analysis of a mutant, hcef1, in chloroplast fructose-1,6-bisphosphatase demonstrates that C₃ plants are capable of high steady state fluxes of cyclic electron flow around photosystem I, which is important for chloroplast energy balance and involves the NAD(P)H dehydrogenase, but not the PGR5, pathway.

The expression of the chloroplast genome requires specialized proteins that are coded in the nucleus and imported into the organelle. We have identified such a protein that binds the leading end of the mRNA for the most abundant chloroplast enzyme. The function of this novel stabilization factor is conserved from green algae to land plants.

Nitric oxide serves as a signal in biotic and abiotic stress responses in plants, yet little is known about its metabolism under aerobic conditions. Using a genetic screen to isolate mutants defective in nitric oxide accumulation, a prohibitin gene was identified that regulates nitric oxide levels and affects stress responses that use nitric oxide signaling.

14-3-3 proteins bind and regulate phosphorylated client proteins involved in diverse biological processes in eukaryotic organisms. This work reports that a tomato 14-3-3 protein regulates plant immunity by altering the abundance of a positive regulator of cell death.

This study describes the biosynthetic dynamics of diterpene glycosides abundant in a wild tobacco and highlights glycosylation and malonylation as key biosynthetic steps producing the diversity of compounds observed. It shows that plants silenced in diterpene glycoside production suffered more damage from herbivores in their natural habitat and were higher-quality food for a specialist herbivore.