Plant metabolism and defence strategies in the flowering stage: Time‐dependent responses of leaves and flowers under attack

Abstract

Plants developing into the flowering stage undergo major physiological changes. Because flowers are reproductive tissues and resource sinks, strategies to defend them may differ from those for leaves. Thus, this study investigates the defences of flowering plants by assessing processes that sustain resistance (constitutive and induced) and tolerance to attack. We exposed the annual plant Brassica nigra to three distinct floral attackers (caterpillar, aphid and bacterial pathogen) and measured whole‐plant responses at 4, 8 and 12 days after the attack. We simultaneously analysed profiles of primary and secondary metabolites in leaves and inflorescences and measured dry biomass of roots, leaves and inflorescences as proxies of resource allocation and regrowth. Regardless of treatments, inflorescences contained 1.2 to 4 times higher concentrations of primary metabolites than leaves, and up to 7 times higher concentrations of glucosinolates, which highlights the plant's high investment of resources into inflorescences. No induction of glucosinolates was detected in inflorescences, but the attack transiently affected the total concentration of soluble sugars in both leaves and inflorescences. We conclude that B. nigra evolved high constitutive rather than inducible resistance to protect their flowers; plants additionally compensated for damage by attackers via the regrowth of reproductive parts. This strategy may be typical of annual plants.

Phenological Variations in the Content of Polyphenols and Triterpenoids in Epilobium angustifolium Herb Originating from Ukraine

“…The content of the metabolites included increased from early flowering to mass flowering for flowers, but decreased in leaves. This trend is likely due to several factors, including physiological changes in the plant during the flowering phase and its metabolism [ 46 , 47 ]. From mass flowering to late flowering, the opposite situation occurred: the quantity of metabolites in Epilobium samples decreased in flowers and increased in leaves.…”

Host plant phenology shapes aphid abundance and interactions with ants

“…Nutritional differences in phloem sap (e.g. C:N) could underlie this effect (Douglas 2006), although few studies have directly assessed changes in phloem sap across flowering stages (Corbesier et al 2001, Dinant et al 2010, Chrétien et al 2022). Aphids generally benefit by feeding on actively growing tissues such as expanding leaf buds or developing flower stems (Kundu and Dixon 1995, Guldemond et al 1998, Hardy et al 2015, White 2015).…”

Early and Late Transcriptomic and Metabolomic Responses of Rhododendron ‘Xiaotaohong’ Petals to Infection with Alternaria sp.

“…Moreover, nucleotide-binding leucine-rich repeat receptors (NLRs) recognize, either directly or indirectly, effector molecules secreted by the pathogen, instigating the second immune system, which is known as effector-triggered immunity (ETI) [ 6 ]. These innate immune systems work cooperatively, producing downstream responses such as the biosynthesis of plant hormones, the production of reactive oxygen species (ROS), the accumulation of secondary metabolites, the induction of stomatal closure, the triggering of hypersensitive response (HR), and the activation of defense-related gene expression [ 7 , 8 , 9 , 10 ].…”