Inbreeding Depression in Solanum carolinense (Solanaceae) under Field Conditions and Implications for Mating System Evolution

Abstract

The clonal weed Solanum carolinense exhibits plasticity in the strength of its self-incompatibility (SI) system and suffers low levels of inbreeding depression (δ) in the greenhouse. We planted one inbred and one outbred plant from each of eight maternal plants in a ring (replicated twice) and monitored clonal growth, herbivory, and reproduction over two years. Per ramet δ was estimated to be 0.63 in year one and 0.79 in year two, and outbred plants produced 2.5 times more ramets than inbred plants in the spring of year two. Inbred plants also suffered more herbivore damage than outbred plants in both fields, suggesting that inbreeding compromises herbivore resistance. Total per genet δ was 0.85 over the two years, indicating that S. carolinense is unlikely to become completely self-compatible, and suggesting that plasticity in the SI system is part of a stable mixed-mating system permitting self-fertilization when cross pollen limits seed production.

Inbreeding in horsenettle (Solanum carolinense) alters night-time volatile emissions that guide oviposition byManduca sextamoths

“…By contrast, volatile induction in response to insect feeding was attenuated in inbred plants, which consequently recruited fewer predators and parasitoids than herbivore-damaged outbred plants [16]. These findings suggest that the overall volatile signalling phenotype of horsenettle is compromised by inbreeding, consistent with a previous observation of dramatic impacts of inbreeding on plant fitness and plant susceptibility to herbivore damage in the field [31].…”

“…tomato and potato) [46 -48]. Tobacco hornworm larvae (M. sexta) have been observed feeding on S. carolinense within the area from which our laboratory populations are collected [31,46].…”

Cascading effects of host plant inbreeding on the larval growth, muscle molecular composition, and flight capacity of an adult herbivorous insect

“…These plants have been maintained via root cuttings following cold treatments (4 °C) and used for subsequent greenhouse and field studies of the effects of inbreeding on plant growth and reproduction (Mena‐Ali, Keser & Stephenson ; Kariyat et al . ). Field, greenhouse and laboratory studies using ramets from subsets of these genets have shown that inbreeding affects (i) resistance to herbivores (Delphia et al .…”

Inbreeding compromises host plant defense gene expression and improves herbivore survival

“…Two ramets were produced from each of the original 16 field-collected plants; flowers from one ramet were cross-pollinated (outbred), while flowers from the second ramet were self-pollinated (inbred). 19,20 Plants used in this experiment were produced by propagating horizontal root cuttings from one inbred and one outbred plant from 3 maternal families (designated B1, B3, and B4; for details see ref. 20).…”

“…19,20 Plants used in this experiment were produced by propagating horizontal root cuttings from one inbred and one outbred plant from 3 maternal families (designated B1, B3, and B4; for details see ref. 20). Twelve horsenettle plants from each genet (3 maternal families £ 2 breeding types) were placed into separate rearing cages (71 cm £ 57 cm £ 66 cm; L £ W £ H) in a greenhouse (16:8 L:D; 25:22 C; 65% RH); plants were 6-8 weeks old and were not flowering.…”