3 Seed characteristics Seeds mature late in the late spring Recalcitrant seed behaviour: Intolerant of drying and prolonged storageRecommended storage conditions: 2–5oC, for 1–2 years
4 A B C D MATURE Seed Development Stages fertilization histodifferentiation maturation maturation drying SEED________________________________________________________________________________- cell division reduced metabolism- cell differentiation- cell expansion quiescentor storage reserve dormantdeposition desiccation protectantsRecalcitrant seedOrthodox seed
5 Purpose:To induce tolerance to desiccation and cryopreservation.Hypothesis:Mature silver maple seeds have not completed seed maturation.It is possible to induce silver maple axes to complete maturationrelated events, such as those associated with desiccation tolerance.
6 Desiccation treatments to a 10% water content: Fast: activated silica gelMedium: axes placed over different saturated solutionsSlow: “ “
7 Figure 1. Silver maple axes’ water content [ ] and root growth [ ] during slow [ ], medium[ ]and fast [ ]desiccation.
8 2-week treatments used to induce axes to continue the maturation stage of developmentFreshly isolated axes on mediaMedia contained:- sucrosenitrogenvitaminsABAand/ ortetcyclacisTo promotedevelopmentalevents
9 Tetcyclacis Triazole plant growth retardant Reduces ABA catabolism Inhibits GA biosynthesis
10 Table 1. Germination of desiccated (medium rate) Table 1. Germination of desiccated (medium rate)ABA- and TC-treated axes.2 wk treatment% growth afterdesiccation *shoots rootsControl-10 a aControl-20 a b10-6 M TC22 b c20 M ABA0 a d20 M ABA TC97 c d60 M ABA0 a d60 M ABA TC63 d d* Values followed by the same letter down a column are not significantlyDifferent (P>0.05) based on a Duncan Waller’s test of the means.
11 A) C) B) B) D) Growth of control-2 axes (A), desiccated 20 M & TC treated axes (B,C) and ABAtreated axes (D).B)D)
12 Table 2. Germination of desiccated (medium rate) ABA- Table 2. Germination of desiccated (medium rate) ABA-and TC-treated axes after cryopreservation for 24 h.2 wk axes treatment:% growth aftercryopreservationshoots rootsControl-110-6 M TC20 M ABA20 M ABA TC60 M ABA60 M ABA TC
13 After 24 months of storage at –196oC: 1) 20 M ABA & TC treated axes – 50% growth2) 60 M ABA & TC treated axes – 31% growth
14 // Figure 2. Abscisic acid content during axes development (DAA) and after shedding from the tree (DAS).//DAADAS
15 * * Figure 3. Abscisic acid content of axes treated (42 DAA)Figure 3. Abscisic acidcontent of axes treatedwith ABA and tetcyclacisfor 2 weeks.**
16 2-dimensional gel electrophoresis of axes proteins A) Control-1 axesB) 20 M ABA& TC treated axes
17 Figure 4. Western blot of a one-dimensional electrophoresis separation of proteins isolated from 2-week treated axes.~ probed with dehydrin antibodyC, control-1; TC, tetcyclacis
18 Figure 5. % water content of axes after the 2 week treatments. 2 wkTreatments:
19 SummaryABA and TC treatment: can induce tolerance to desiccation and cryopreservation.ABA and TC treated axes maintained a high ABA content.20 M ABA and TC treated axes continued developmental events.
20 ConclusionSilver maple axes when shed from the tree are still undergoingdevelopmental events (e.g., seed storage protein synthesis).Silver maple axes can be induced to continue maturation after seedhave been shed from the tree.
21 Application of this treatment Treating intact seeds with ABA and tetcyclacisPacluobutrazol and ABA: potential as a seed treatment
22 Acknowledgements Mike Brown Bernie Daigle Kathleen Forbes Mark Kalous Garry ScheerDale SimpsonCarrie-Ann Whittle