Strigolactones and gibberellic acid regulate aphid fecundity in pea
Atmospheric CO2 levels influences plant growth and susceptibility to pathogens and pests but there is little information on the mechanisms involved. We therefore studied how elevated atmospheric CO2 concentrations (eCO2) effects shoot branching and the performance of the pea aphid on wild type peas and on mutants that are defective in either strigolactone (SL) synthesis or signalling. Shoot branching and dry biomass accumulation were increased under eCO2 conditions in all lines. However, eCO2
... es. However, eCO2 decreased shoot water content only in the wild type peas but not in the SL mutants. Growth under eCO2 decreased the levels of salicylic acid and increased jasmonic acid in the wild type peas, without any significant effect on aphid fecundity. However, aphid numbers were increased on the SL mutants under both ambient and eCO2 conditions. Of the shoot phytohormones measured in this study, only gibberellic acid (GA3) was decreased in the SL mutants, an effect that was exacerbated by eCO2. There was a negative correlation between aphid fecundity and shoot GA3 levels. Taken together, these studies provide confirm that eCO2 modifies the levels of defence hormones and provides the first evidence that SL and GA3 are important regulators of plant responses to phloem-feeding insects. Johnson X., Brcich T., Dun E.A., Goussot M., Haurogne K., Beveridge C.A., Rameau C. (2006) Branching genes are conserved across species. Genes controlling a novel signal in pea are coregulated by other longdistance signals. Plant Physiology 142 : 1014-26. Kalliola M., Jakobson L., Davidsson P., Pennanen V., Waszczak C., Yarmolinsky D., Zamora O., Palva E.T., Kariola T., Kollist H., Brosche M. (2020) Differential role of MAX2 and strigolactones in pathogen, ozone, and stomatal responses. Plant Direct 4: 1-14. Kaloshian I., Walling L.L. (2016) Hemipteran and dipteran pests: Effectors and plant host immune regulators. Journal of Integrated Plant Biology 58: 350-361. Kerchev P.I., Karpińska B., Morris J.A., Hussain A., Verrall S.R., Hedley P.E., Fenton B., Foyer C.H., Hancock R.D. (2013) Vitamin C and the abscisic acid-insensitive 4 (ABI4) transcription factor are important determinants of aphid resistance in Arabidopsis.Antioxidants and Redox Signaling 18 : 2091-2105. Kiani M., Szczepaniec A. (2018) Effects of sugarcane aphid herbivory on transcriptional responses of resistant and susceptible sorghum.BMC Genomics. 19: 774. Elevated [CO 2 ] alleviates the impacts of water deficit on xylem anatomy and hydraulic properties of maize stems. Plant Cell and Environment 43 :563-578.