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Here, we examined leaf and EFN morphology and development of two Passiflora specieswith distinct leaf shapes, and compared the phenotype of these to transgenics with manipu-lated activity of the age-dependent miR156, which targets several SQUAMOSAPROMOTER-BINDING PROTEIN-LIKE (SPL) transcription factors. Low levels of miR156 correlated with leaf maturation and EFN formation in Passiflora edulisand P. cincinnata. Accordingly, manipulating miR156 activity affected leaf heteroblasty andEFN development. miR156-overexpressing leaves exhibited less abundant and tiny EFNs inboth Passiflora species. EFN abundance remained mostly unchanged when miR156 activitywas reduced, but it led to larger EFNs in P. cincinnata. Transcriptome analysis of young leafprimordia revealed that miR156-targeted SPLs may be required to properly express leaf andEFN-associated genes. Importantly, altered miR156 activity impacted sugar profiles of thenectar and modified ecological relationships between EFNs and ants. Our work provides evidence that the miR156/SPL module indirectly regulates EFN develop-ment in an age-dependent manner and that the EFN development program is closely asso-ciated with the heteroblastic developmental program of the EFN-bearing leaves.
Soares et al. 2024 New PhytologistDOI: 10.1111/nph.20343
Here, we show that the regulation of TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) LANCEOLATE ( TCP2/LA ) by miR319 is crucial for tomato fruit morphology. The loss of miR319 regulation in the semi‐dominant La mutant led to a premature SlTCP2/LA expression during gynoecium patterning, which results in modified cell division during carpel development. As a consequence, La mutants exhibited elongated ovary and fruit shape, and a reduced number of ovules and seeds. Elongated fruit shape in La may be partially due to the SlTCP2/LA ‐mediated repression of OVATE activity in young floral buds. Further analysis showed that the de‐repression of SlTCP2/LA decreases auxin responses in young floral buds by directly repressing SlYUCCA4 expression, but SlTCP2/LA also acts in parallel with ENTIRE ( E ) to orchestrate fruit morphology and seed production. Our study defines a novel miRNA‐based molecular link between the domestication‐associated OVATE gene and auxin responses. Given the striking variation in fruit morphology among members of the Solanaceae family, fine‐tuning regulation of gene expression by miRNA coupled with modulation of auxin dynamics may be a common driver in the evolution of fruit shape diversity.
Carvalho Jr. et al. 2024 Plant Journal