ETD system

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Tesi etd-09192018-161810

Thesis type
Tesi di laurea magistrale
Investigation into the biological fitness of circumnutation during germination of C.quinoa
Corso di studi
relatore Prof. Sorce, Carlo
relatore Prof. Guglielminetti, Lorenzo
relatore Prof. Watahiki, Masaaki
correlatore Prof.ssa Ranieri, Annamaria
correlatore Prof.ssa Spanò, Carmelina
Parole chiave
  • NPA
  • IAA
  • auxin polar transport
  • circumnutation
  • C.quinoa
  • yucasin
Data inizio appello
Secretata d'ufficio
Data di rilascio
Riassunto analitico
On poor nutrients medium, Quinoa seeds have a 8h quick germination, followed by upcoming radicles which make a noticeable circumnutation movements for 48h and over. Circumnutational movements have been reported in all growing organs, more or less intense, in most of the plants. Darwin and his son Francis, in the power of movement of plants, first collected and reported hundreds of trays of growing root tips to show their “slow” but consistent movements, suggesting the presence of an “inner oscillator” which triggers and rhythms the movement. They also suggested the term “circum-nutation”, meaning a sway around an axis, primary root tips usually sway around the gravity vector, so as C.quinoa. For Holodny-Went an “over compensatory” response of gravitropism was the main and only reason of this phenomenon; partially confirmed by recent studies by microgravity conditions experiments. Recently, a double-oscillator model: inner and gravitropic-driven, was suggest, yet all the genetic and physiological pathways are still unclear. Quinoa seeds show a quick, high amplitude, “macronutation” movement the first 24h after sowing, and a quicker, low amplitude, “micronutation” movement after the first 24h until at least 150h. The frequency and the amplitude of this root movement have, until now, never been reported before in any other plant. This work provides a series of evidence the circumnutational movement is relied on auxin polar transport, and probably not on the de novo synthesis of auxin. The evolution from “macronutation” and “micronutation” appear to be also due to the auxin polar transport. On a concentration-based level switch, some unknown factor may be degraded as soon as auxin levels in the elongation zone are too low, explaining why “macronutation” cannot be recovered. An hypothesis about the biological meaning of the “macronutation” is also suggested: because of the probable harsh, dry, rocky original terrains habitat, a quick germination, a quick, high amplitude movement could allow a “walking pattern”, as well as “strong” tentative to penetrate the soil.