The floral transition is not the developmental switch that confers competence for the Arabidopsis age-related resistance response to Pseudomonas syringae pv. tomato

Abstract

Age-related resistance (ARR) is a plant defense response characterized by enhanced resistance to certain pathogens in mature plants relative to young plants. In Arabidopsis thaliana the transition to flowering is associated with ARR competence, suggesting that this developmental event is the switch that initiates ARR competence in mature plants (Rusterucci et al. in Physiol Mol Plant Pathol 66:222–231, 2005). The association of ARR and the floral transition was examined using flowering-time mutants and photoperiod-induced flowering to separate flowering from other developmental events that occur as plants age. Under short-day conditions, late-flowering plant lines ld-1 (luminidependens-1), soc1-2 (suppressor of overexpression of co 1-2), and FRI+ (FRIGIDA) displayed ARR before the transition to flowering occurred. Early-flowering svp-31, svp-32 (short vegetative phase), and Ws-2 were ARR-defective, whereas early-flowering tfl1-14 (terminal flower 1-14) displayed ARR at the same time as Col-0. While svp-31, svp-32 and Ws-2 produced few rosette leaves, tfl1-14 produced a rosette leaf number similar to Col-0, suggesting that the development of a minimum number of rosette leaves is necessary to initiate ARR competence under short-day conditions. Photoperiod-induced transient expression of FT (FLOWERING LOCUS T) caused precocious flowering in short-day-grown Col-0 but this was not associated with ARR competence. Under long-day conditions co-9 (constans-9) mutants did not flower but displayed an ARR response at the same time as Col-0. This study suggests that SVP is required for the ARR response and that the floral transition is not the developmental event that regulates ARR competence.Electronic supplementary materialThe online version of this article (doi:10.1007/s11103-013-0083-7) contains supplementary material, which is available to authorized users.

Assortment of flowering time and immunity alleles in natural Arabidopsis thaliana populations suggests immunity and vegetative lifespan strategies coevolve

“…In A. thaliana, the effectiveness of defense is indeed regulated by plant development: the onset of age-related resistance in A. thaliana provides a defense barrier against a broad spectrum of pathogens (Rusterucci et al, 2005). In agreement with our findings, the timing of age-related resistance had been reported not to stand under the direct control of flowering time (Wilson et al, 2013). The subset of genes, whose expression variation in natural populations correlated with flowering time, were also enriched among age-regulated genes (hypergeometric test, p= 7.2e-11).…”

High CO2 primes plant biotic stress defences through redox-linked pathways

“…4). Age-related resistance, whereby plants become less susceptible to pathogens as they mature, has been described in Arabidopsis (Kus et al, 2002;Wilson et al, 2013). However, most evidence suggests that high CO 2 does not accelerate senescence.…”

A bacterial parasite effector mediates insect vector attraction in host plants independently of developmental changes

“…MTFs are regulatory hubs for a plethora of physiological processes in plants, including plant immunity (comparable to animal HOX genes); several MTFs appear to (in)directly regulate cytokinin and jasmonic acid (JA) synthesis and response genes 11 , which affect plant-insect interactions 15-18 , such as that of the AY-WB leafhopper vector M. quadrilineatus 19 . In addition, MTFs regulate age-related resistance responses to pests 20 . Therefore, SAP54-mediated degradation of MTFs may modulate plant immunity leading to attraction of the leafhoppers.…”