Transcriptomic and proteomic analyses of seasonal photoperiodism in the pea aphid

ABSTRACT: Aphid adaptation to harsh winter conditions is illustrated by an alternation of their reproductive mode. Aphids detect photoperiod shortening by sensing the length of the night and switch from viviparous parthenogenesis in spring and summer, to oviparous sexual reproduction in autumn. The photoperiodic signal is transduced from the head to the reproductive tract to change the fate of the future oocytes from mitotic diploid embryogenesis to haploid formation of gametes. Because of viviparous parthenogenesis, the whole process takes place in three consecutive generations. To understand the molecular basis of the switch in the reproductive mode, a transcriptomic approach was used to detect significantly regulated transcripts in the heads of the pea aphid Acyrthosiphon pisum. The transcriptomic profiles of the heads of the first generation were slightly affected by photoperiod shortening. This suggests that trans-generation signaling does not occur between the grand-mothers and the viviparous embryos they contain. By analogy, many of the genes regulated in the heads of the second generation are implicated in visual functions, photoreception and cuticle structure. The modification of the cuticle could decrease the storage of N-β-alanyldopamine and provoke an increase in free dopamine concentration. Based in results in Drosophila, modification of the insulin pathway could cause a decrease of juvenile hormones in short-day reared aphids. Biological material for microarray experiments was prepared under two dayly photoperiodic regimes both at constant temperature of 18°C: i) “Short Night” (SN) at 16h of light and ii) “Long Night” (LN) at 12h of light to induce the production of sexual morphs. To initiate the experiment, two groups of 105 L3 larvae were placed either under SN or LN condition. This corresponds to generation G0. At the middle of the photophase, 25 individual were frozen when they had reached both the L4 and the wingless adult (WA) stages, in the two photoperiod conditions. The 55 remaining WA individuals (still divided in two groups) were left on 55 plants to lay their offspring: one larva of the 1st stage (L1) was kept per WA. This larva was selected among the 20 first born larvae. This is the generation G1. At the middle of the photophase, 25 individual were frozen when they had reached both the L2 and the L4 stages, in the two photoperiodic conditions. Thus, 25 individuals from 4 different stages (L4-G0, WA-G0, L2-G1 and L4-G1) were collected in the two photoperiod conditions with 3 biological replicates, forming the 24 samples used for microarray experiments. RNAs from heads of aphids from the two photoperiodic conditions were hybridized one against the other for each stage with a dye-swap.The experimental design is thus 24 arrays which corresponds to the described samples of that series.

ORGANISM(S): Acyrthosiphon pisum

SUBMITTER: Joël BONHOMME 

PROVIDER: E-GEOD-15776 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress