International Journal of Plant Biology

Oxalis tuberosa (oca) is a tuber crop native to the Andes, valued for its nutrition but understudied genetically. Its strict short-day (SD) tuberization suggests a photoperiodic control mechanism similar to that of potato, where an FT-like protein acts as a mobile “tuberigen” signal. To identify this key regulator, we generated a de novo genome assembly for oca using long- and short-read sequencing. Integrated transcriptomic analysis of leaves under long-day (LD) and SD conditions, along with stems, roots, and tubers, enabled gene annotation and expression analysis. Our study focused on the Phosphatidylethanolamine-Binding Protein (PEBP) gene family, the source of florigen and tuberigen signals. We identified 23 OtPEBP genes and characterized their expression patterns. Among these, we discovered three FT-like homologs that are specifically and strongly upregulated in leaves under SD conditions. We therefore propose these genes as the prime candidates for the mobile tuberigen signal in oca. This work provides the foundational genomic resource for O. tuberosa and advances our understanding of the conserved photoperiodic network controlling storage organ formation beyond the Solanaceae family.

Anthracnose is one of the most destructive diseases of avocado worldwide; however, foliar infections remain poorly documented in Peru. We investigated the etiology of necrotic leaf lesions observed in avocado plantations in Amazonas and assessed the in vitro antifungal activity of two Piper essential oils (EOs). Incidence was quantified in a 420-tree plot (n = 150 plants). Two representative isolates (MGS03, MGS04) were obtained from symptomatic leaves and characterized by morphology and multilocus sequencing (ITS, CHS-1, ACT, and TUB2). Maximum-likelihood phylogeny within the C. gloeosporioides species complex clustered with C. fructicola. Pathogenicity tests on detached leaves (unwounded inoculation) reproduced field symptoms and fulfilled Koch’s postulates. The antifungal activity of Piper carpunya and P. aduncum EOs (50–1000 µL L⁻¹) was evaluated using poisoned-medium assays, revealing a strong dose-dependent inhibition of mycelial growth. Inhibition reached >89.8% at 500 µL L⁻¹ and ~100% at 1000 µL L⁻¹, with P. aduncum showing slightly higher activity. This study provides the first confirmed record of C. fructicola associated with necrotic leaf lesions in avocado in Peru and demonstrates the promising antifungal potential of Piper EOs as eco-friendly candidates for anthracnose management.

Cynipid gall wasps are known for their ability to manipulate host plant development, redirecting undifferentiated tissues into complex, highly specialised structures. In this study, we investigated how Andricus quercustozae larvae manipulate axillary bud tissues of Quercus virgiliana across four key stages of gall development: initiation, differentiation and growth, maturation, and lignification. Using detailed histological analyses, we characterised progressive tissue differentiation within galls, focusing on the organisation of nutritive, protective, and vascular tissues. Gall development was marked by sustained hyperplasia and hypertrophy, extensive vascular proliferation, and progressive cell wall lignification, resulting in a complex organ optimised for larval nutrition and protection. To complement these anatomical observations, we conducted a preliminary transcriptomic comparison between gall tissue and unmodified leaf tissue. Gene expression analyses revealed suppression of photosynthesis-related functions and coordinated modulation of developmental, regulatory, and metabolic pathways, consistent with a transition from assimilatory leaf tissue to a specialised nutrient sink. Integration of anatomical and transcriptomic evidence supports a model in which cynipid gall wasps intervene at key regulatory nodes of bud development, progressively reprogramming host tissues to form a functionally autonomous gall. These findings provide new insight into the extended phenotype and highlight the plasticity of plant developmental programmes under insect control.