Research Briefing in 2022

The higher-order organization of the monoterpenoid indole alkaloid biosynthesis in Catharanthus roseus leaves was dissected using single-cell RNA sequencing. This work opens the door to elucidate the spatial distribution of plant specialized metabolism at single-cell resolution, which will improve our understanding of the biosynthesis, transport and storage of specialized metabolites.

The TPLATE complex (TPC) is an ancient multi-subunit adaptor complex, essential for clathrin-mediated endocytosis in plants. We found that the evolutionary specific SH3 domain on the large TPC subunit, TASH3, recognizes ubiquitinated cargo proteins at the plasma membrane, providing a link between endocytosis and internalization of ubiquitinated proteins.

Sweet potato weevils (SPWs) pose one of the greatest challenges to sweet potato production worldwide; however, the genetic basis of SPW resistance remains unclear. This study identifies two major SPW resistance genes in sweet potato and provides new insights into the mechanisms by which sweet potato defends against SPWs.

Appropriate root system architecture (RSA) is essential for efficient water and nutrient use, especially in high-density planting conditions in intensive maize cropping systems. Modern maize breeding has favoured steeper, narrower root systems. We identified two auxin-related genes, ZmRSA3.1 and ZmRSA3.2, which can potentially be used for future improvement of maize RSA.

Plant cell wall pectin has a homogalacturonan or rhamnogalacturonan backbone. Incomplete knowledge of RG-I biosynthetic enzymes has impeded in vitro pectin synthesis and pectin structure and function studies. Here, RGGAT1 is identified as a GT116 RG-I backbone biosynthetic galacturonosyltransferase that produces polymeric RG-I backbone when expressed with GT106 RG-I rhamnosyltransferases.

Duplication of KCBP, which encodes a plant-specific microtubule-based kinesin motor, occurs solely in legumes of the clade that form symbiosomes. The nodule-enriched KCBP (nKCBP) is co-opted by rhizobia to control central vacuole morphogenesis in symbiotic cells, thus achieving symbiosome development and nitrogen fixation.

Root hairs have long been considered to elongate exclusively by so-called tip growth, in which the new building material is deposited at the root hair apex. Using a set of newly developed imaging experiments, we revealed that root hair shank expansion can substantially contribute to total root hair growth.

Guard cell outward rectifying potassium (GORK) channel activity is associated with channel clustering at the guard cell membrane. We show that clustering and gating both depend on an extended ‘antenna’ of bound channel voltage sensors. Uncoupling clustering and gating facilitates K⁺ flux, accelerating stomatal movements in environments typical for plants in the field.

A major bottleneck in plant breeding is the establishment or breakage of genetic linkages by random, naturally occurring meiotic recombination. This problem can be overcome by CRISPR–Cas-mediated chromosome engineering. By inverting ~17 Mb of chromosome 2 of Arabidopsis thaliana, we almost completely suppressed genetic crossovers in nearly the entire chromosome.

Cooperation between nitrogen assimilation and photosynthesis is central for plant growth and development in adaption to changing environmental conditions. This work reveals that the plant energy sensor SnRK1 represses nitrate signalling by phosphorylating NODULE INCEPTION PROTEIN-LIKE PROTEIN (NLP7) to promote its degradation in response to carbon deficiency or nitrate depletion.

We applied single-molecule nanopore sequencing to over 120 million full-length RNAs, including the poly(A) tail, from various tissues and plant species. The resulting dataset enables the genome-wide characterization of plant poly(A) tails at the single gene level across different tissues and species.

Plant microtubules align along directions of anisotropic mechanical stress. Live cell imaging of epidermal pavement cells reveals that cellulose synthase complexes (CSCs) are present in regions of anisotropic mechanical stress in patterns similar to those of microtubules. The coupling of microtubules and CSCs hampers the response of microtubules to mechanical stresses.

Cellular responses to environmental and developmental signals depend on the recruitment of transcription factors to specific genes. Although PIF4 and CDF2 belong to different transcription factor families in Arabidopsis thaliana, data suggest that they act co-operatively to bind to specific target genes in the gene network that regulates hypocotyl cell elongation.

Charles Darwin suggested that phylogenetic distance between introduced aliens and natives might determine invasion success, but he was inconclusive about the direction of the relationship. An analysis of alien plants introduced to Southern Africa for cultivation reveals that the relationship changes direction from one invasion stage to the other.

The biological importance of centromere distribution in the nucleus, which is classified as polarized or dispersed, has been debated. Molecular and cytogenic analyses have revealed that two regulatory processes establish a dispersed distribution and that centromere distribution might be linked to the maintenance of genome integrity.

A national survey of organic farmers shows that the use of sustainable farming practices differs with farm size. Although organic agriculture is often considered to be homogeneous, this survey suggests that a greater focus on farm size and socio-technical change is needed to improve the sustainability of food production.

Grain yield in bread wheat (Triticum aestivum L.) is largely determined by spike architecture. Mutations in DUO-B1, encoding an AP2/ERF protein, result in a spike architecture with extra spikelets that increases both grain number per spike and yield under field conditions. Genetically modifying DUO-B1 has the potential to increase cereal production.

Methylation is a frequent modification of glycans and polysaccharides. This process relies on the transport of cytosolic S-adenosyl-l-methionine (SAM) into the Golgi lumen. This work identifies Golgi-localized major facilitator superfamily transporter members as putative SAM transporters in plants and reveals their importance for polysaccharide methylation and maintenance of the properties of cell walls.

Next-generation crop protection strategies must be clean and green as well as effective. Delivery of double-stranded RNA (dsRNA) as a BioClay spray to control the sap-sucking pest whitefly is one such strategy. This tool disrupts multiple whitefly life cycle stages in planta, with adjuvant-enhanced foliar uptake complementing the clay-mediated delivery of dsRNA.

Xylan-rich nanodomains at pit borders of xylem vessels determine a pitted wall pattern by anchoring cellulosic nanofibrils at the pit edges and are crucial to support vessel robustness, water transport and leaf transpiration. These nanocompartments are mostly produced by the de novo xylan synthase IRREGULAR XYLEM (IRX)10 and its homologues.