Cowan, G. | bioRxiv Science

bioRxiv2024

GERMIN3 plays a role in plasmodesmatal gating to regulate meristem activation related to tuberisation, tuber dormancy release and stem branching in potato

O_LIGERMIN3 has previously been identified as a target of the tuberigen activation complex suggesting a function in potato tuberisation but its role is presently unknown. C_LIO_LITo understand the role of GERMIN3 we analysed morphological, agronomic and molecular phenotypes in transgenic lines. C_LIO_LIGERMIN3 over-expressing lines of Solanum tuberosum ssp. andigena exhibited increased tuber yields under permissive conditions and enhanced tuber numbers. Post-harvest tuber sprouting exhibited reduced apical dominance with increased numbers of sprouts. Apical dominance was reduced in aerial tissues of mature plants where stem growth from axillary buds was activated. Similar results were observed in the commercial cultivar Desiree. Over-expression of GERMIN3 had no impact on the expression of SP6A, a positive regulator of tuberisation or TFL1B, a negative regulator. The GERMIN3 protein localised to the endoplasmic reticulum and transient expression in N. benthamiana leaves resulted in plasmodesmatal gating allowing intercellular transport of GFP-tagged sporamin independent of GERMIN3 oxalate oxidase activity. C_LIO_LIGERMIN3 affects tuberisation and other developmental processes by facilitating meristem activation. This identifies GERMIN3 as a novel protein associated with control of plasmodesmatal transport and supports the importance of plasmodesmatal gating in the regulation of key potato developmental processes. C_LI

plant biology↗

bioRxiv2024

Mutation of the allexivirus-specific P40 gene of Wineberry latent virus, an isolate of Blackberry virus E, greatly reduces virus multiplication

The complete sequence of Wineberry latent virus (WLV), a previously reported but uncharacterised Rubus-infecting virus with flexuous particles, has been determined. Analysis shows WLV to have 76% overall nucleotide sequence identity to the more recently discovered Blackberry virus E, an allexivirus belonging to the subgroup of these viruses that lack the 3 proximal cysteine-rich protein (CRP) gene present in Allium-infecting allexiviruses. An infectious cDNA clone of WLV was constructed and a mutation introduced into the P40 gene, which is an allexivirus-specific gene of unknown function. In addition, the infectious clone was modified to express the green fluorescent protein (GFP) as an N-terminal fusion to the WLV coat protein (CP). Using this GFP overcoat strategy it was possible to follow the multiplication and movement of the virus in infected Chenopodium quinoa and spinach leaves. Introduction of the frameshift mutation into the P40 gene of WLV reduced virus accumulation by 97%, and with the GFP overcoated WLV the P40 mutation almost entirely abolished GFP fluorescence in inoculated leaves suggesting that the WLV P40 protein is required for normal levels of virus multiplication. RepositoriesWLV complete sequences deposited at GenBank. Accession Nos. MZ944847.1, OQ877124.1

plant biology↗