Untargeted metabolomic profiling reveals that different responses to self and cross pollination in each flower morph of the heteromorphic plant Plumbago auriculata

Comparative stigmatic transcriptomics reveals self and cross pollination responses to heteromorphic incompatibility in Plumbago auriculata Lam.

“…Notably, 2 hours post SC pollination, pollen-stigma cross-linking was evident, with distinct morphological differences observed between the crosses “P × T” and “T × P”. In “T × P”, a “foot” structure penetrated the stigma, unlike in “P × T”, where germinated pollen adhered to the stigma without forming a “foot” structure, and the surrounding papillae became less globular ( Hu et al, 2019 ). Additionally, SC pollen exhibited a faster growth rate on the thrum morphotype compared to the pin morphotype.…”

“…At 8:00 a.m., pistils were manually pollinated with SC pollination: “P × T” (pin pistils inter - pollinated with thrum pollen), “T × P” (thrum pistils inter - pollinated with pin pollen) and SI pollination: “T × T” (thrum pistils intra - pollinated with thrum pollen), “P × P” (pin pistils intra - pollinated with pin pollen). They were collected 2 h later, at 10:00 a.m. ( Hu et al, 2019 ; Hu et al, 2020 ). Fifty milligrams of each sample was processed for analysis ( Figure 1 ).…”

“…A frequently encountered HetSI plant with dry stigmas is Plumbago auriculata Lam. (Plumbaginaceae) ( Hu et al, 2019 ). The Plumbaginaceae family comprises approximately 650–1000 species, with a significant number of them being HetSI plants ( Mucina and Hammer, 2019 ).…”

“…These plants serve as excellent research systems for HetSI studies. Through artificial pollination, we found that once pollination occurs with compatible pollen, a series of signaling events are triggered, including pollen adhesion, germination, pollen tube elongation, and fertilization, all of which occur within 4 h. However, no pollen tubes were discovered in SI pollinations ( Hu et al, 2019 ). The metabolomic study revealed that mature styles stored abundant nutrients required for the energy-consuming process in the pollen tube growth.…”

“…Despite the failure of fertilization in SI pollinations, the styles still contained sufficient energy reserves to support the growth of other SC (self-compatible) pollen grains ( Figure 1 ). Moreover, the morphology and metabolome of SI in pin and thrum flower styles were found to be distinct ( Hu et al, 2019 ; Hu et al, 2020 ). This led us to hypothesize that different flower types may have varying mechanisms for SI.…”