Darren Touchell

Acetyl salicylic acid (Aspirin) and salicylic acid induce multiple stress tolerance in bean and tomato plants

The hypothesis that physiologically activeconcentrations of salicylic acid (SA) and itsderivatives can confer stress tolerance in plants wasevaluated using bean (Phaseolus vulgaris L.) andtomato (Lycopersicon esculentum L.). Plantsgrown from seeds imbibed in aqueous solutions (0.1--0.5 mM) of salicylic acid or acetyl salicylic acid(ASA) displayed enhanced tolerance to heat, chillingand drought stresses. Seedlings acquired similarstress tolerance when SA or ASA treatments wereapplied as soil drenches. The fact that seedimbibition with SA or ASA confers stress tolerance inplants is more consistent with a signaling role ofthese molecules, leading to the expression oftolerance rather than a direct effect. Induction ofmultiple stress tolerance in plants by exogenousapplication of SA and its derivatives may have asignificant practical application in agriculture,horticulture and forestry.

Benzoic acid may act as the functional group in salicylic acid and derivatives in the induction of multiple stress tolerance in plants

Benzoic acid, sulfosalicylic acid and methyl salicylic acid wereevaluated for their regulatory role in inducing multiple stress tolerance inbean (Phaseolus vulgaris cv Brown Beauty) and tomato(Lycopersicum esculentum cv Romano) plants. All threemolecules were effective in inducing tolerance to heat, drought and chillingstress similar to that reported previously for salicylic and acetylsalicylicacids. Benzoic acid is effective at lower concentrations than salicylic acid orits derivatives. The benzoic acid structural portion is common to all fivemolecules and is the most likely basic functional molecular structure impartingstress tolerance in plants.

Smoke-saturated water promotes somatic embryogenesis in geranium

The effect of smoke saturated-water (SSW) on somatic embryogenesis was studied using geranium hypocotyl culture as a model system. Treatment of explants with 10% SSW or the inclusion of SSW with thidiazuron, a compound which induces somatic embryogenesis, enhanced the embryogenic potential of the geranium hypocotyl culture. Prolonged exposure to SSW was detrimental to embryogenesis. The SSW treatment also accelerated the rate of embryo development suggesting a growth regulatory role of SSW.

Stereochemical arrangement of hydroxyl groups in sugar and polyalcohol molecules as an important factor in effective cryopreservation

The efficacy of several sugars and polyalcohols in preculture medium was investigated using Anigozanthos viridis ssp terraspectans Hopper (Haemodoraceae), a threatened plant species endemic to the south west of Western Australia. A vitrification protocol involving preculturing of shoot apices for 3 days on different concentrations of sugars and polyalcohols, followed by incubation in plant vitrification solution 2 (PVS2) for 25 min, prior to immersion in liquid nitrogen (LN) and warming resulted in shoot tip survival ranging from 34 to 84%. High levels of survival were obtained with polyalcohols, compared to sucrose, glucose, trehalose and raffinose when used at the same molarity (0.4 M) or at the equivalent concentration of total hydroxyl (OH) groups present in molecules. In both cases glycerol proved more effective. When polyalcohols (ribitol and erythritol) with similar stereochemical arrangement of OH groups as glycerol were examined, at the same molarity (0.4 M) and with equivalent OH numbers, higher survival was achieved when the total number of OH groups present was the same as glycerol. Additionally, when the structural isomers mannitol/sorbitol and ribitol/xylitol were compared at the same molarity (0.4 M), the isomer with the higher number of OH groups along the same side resulted in significantly higher levels of post-LN survival. We propose that the mode of action of polyalcohols is based not on molarity, but on the total number of OH groups present in the medium. Furthermore, based on these results we propose that the orientation of OH groups is a determining factor in effective cryopreservation.

Cryopreservation of seed of Western Australian native species

The ability of seed of native Western Australian species to be stored using cryopreservation methods was investigated by subjecting seed of 90 native species representing 84 genera and 33 families to storage in liquid nitrogen. Seed of 68 native Western Australian species were germinated after storage in liquid nitrogen for two weeks following treatments which involved direct plunging into liquid nitrogen or slow cooling at 0.4°C min−1 in 15% dimethyl sulphoxide (DMSO) or slow cooling at 0.4°C min−1 in 35% DMSO. The largest number of species (37) responded positively to direct plunging without pretreatments, with only 10 species responding to slow cooling in 15% DMSO. Thirty one species had enhanced germination and 10 species depressed germination after any of the liquid nitrogen treatments. There were no trends in a species ability to survive liquid nitrogen storage and freezing regime, moisture content, seed size or taxonomic relatedness. However, hard seeded species belonging to the families Caesalpinaceae and Papilionaceae showed a consistently high degree of tolerance to liquid nitrogen storage. Significant physical damage to seed and cotyledons only occurred in Templetonia retusa (Papilionaecae) and this was alleviated by nicking the seed coat. This study indicates that seed of a large proportion of native Western Australian species may be amenable to storage in liquid nitrogen and that at least 40% of the listed rare and endangered species of Western Australia could be maintained in this way.