Sex versus parthenogenesis: a transcriptomic approach of photoperiod response in the model aphid Acyrthosiphon pisum (Hemiptera: Aphididae).
Most aphids develop a cyclic parthenogenesis life-cycle. After several generations of viviparous parthenogenetic females, it follows a single annual generation of sexual individuals, usually in autumn, that mate and lay the sexual eggs. Shortening of photoperiod at the end of the summer is a key factor inducing the sexual response. With the survey here reported we aimed at identifying a collection of candidate genes to participate at some point in the cascade of events that lead to the sexual phenotypes. Following a suppression subtractive hybridization methodology (SSH) on the model aphid Acyrthosiphon pisum, we built and characterised two reciprocal cDNA libraries (SDU and SDD) enriched respectively in genes up-regulated or down-regulated by short photoperiod conditions that lead to the sexual response in this aphid species. A total of 557 ESTs were obtained altogether representing 223 non-overlapping contigs. 29% of these were new sequences not present in previous aphid EST libraries. BLAST searches allowed putative identification of about 54% of the contigs present in both libraries. Relative quantification of expression through real-time quantitative PCR demonstrated the differential expression in relation with the photoperiod of 6 genes (3 up-regulated and 3 down-regulated by shortening the day length). Among these, expression of a tubulin gene, two cuticular proteins and a yet unidentified sequence along the day-night cycle was further investigated. Implications for current studies on gene regulation of the dichotomy sex vs. parthenogenesis in aphids are discussed.
Cortés
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Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Apartado de Correos 22085, 46071, València, Spain.
Tagu
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Simon
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JC
Moya
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A
Martínez-Torres
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D000818:Animals; D001042:Aphids / Q000145:classification / Q000235:genetics / Q000502:physiology*; D020224:Expressed Sequence Tags; D005786:Gene Expression Regulation; D015723:Gene Library; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D010312:Parthenogenesis; D017440:Photoperiod; D012726:Sexual Behavior, Animal
D019476:Insect Proteins