The adaptive function of touch-sensitive stigmas

Krishna, Shivani; Jos, Elsa M.; Somanathan, Hema

doi:10.1007/s11258-022-01281-2

Cited by 2 publications

(1 citation statement)

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“…Less widely known are thigmonastic movements of floral parts upon contact by animal pollinators (Braam 2005); these include moderately rapid movements of stamens and corolla (Henning et al 2018; Dai et al 2021; Li et al 2022; Tagawa et al 2022) and rapid (as little as 2 seconds) closure of stigma lobes in many members of the Lamiales (Newcombe 1922). Stigma thigmonasty is widespread, evolutionarily labile (Friedman et al 2017), and linked to reproductive fitness (Fetscher and Kohn 1999; Krishna et al 2023), making it an appealing system for understanding the evolutionary genetic of floral mechanosensing and motion. However, despite nearly 150 years of study of touch-sensitive stigma movement (Darwin 1877; Todd 1879; Miyoshi 1891; Burck 1902; Lloyd 1911; Newcombe 1922, 1924), we still know almost nothing about its genetic mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Undoing the ‘nasty: dissecting touch-sensitive stigma movement (thigmonasty) and its loss in self-pollinating monkeyflowers

Fishman,

McIntosh,

Nelson

et al. 2024

Preprint

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Rapid touch-sensitive stigma closure is a novel plant reproductive trait found in hundreds of Lamiales species. The origins, mechanisms, and functions of stigma closure remain poorly understood, but its repeated loss in self-fertilizing taxa and direct tests implicate adaptive roles in animal-mediated cross-pollination. Here, we document several additional losses of stigma closure in monkeyflowers (Mimulus), then use quantitative trait locus (QTL) mapping and gene expression analyses to provide a first glimpse into the genetic and molecular basis of stigma mechanosensing and movement. Variation in stigma closure in hybrids between selfer/non-closer Mimulus nasutus and outcrosser/fast-closer M. guttatus has a moderately complex genetic basis, with four QTLs together explaining ~70% of parental divergence. Loss of stigma closure in M. nasutus appears genetically independent from other aspects of the floral selfing syndrome and from a parallel loss in M. parishii. Analyses of stylar gene expression in closer M. guttatus, M. nasutus, and a rare M. guttatus non-closer genotype identify functional candidates involved in mechanosensing, turgor regulation, and cell wall remodeling. Together, these analyses reveal a polygenic genetic architecture underlying gain and loss of a novel plant movement, illuminate selfer-outcrosser reproductive divergence, and initiate mechanistic investigations of an unusually visible manifestation of plant intelligence.

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