Triticum aestivum L. cv. Nabão seeds were obtained as previous described (Lidon et al., 2011-2nd COST FA0905 Meeting, Venice), from plants grown in a growth chamber (EHHF10000, Aralab, Portugal) under environmental controlled conditions (80% RH; 24/20ºC day/night temperatures; PPFD of ca 700 µmol m-2 s-1, 12 h photoperiod). Plants were fertilized with Zn and Fe using a normal (s) and a 5 fold (5s) concentration of all nutrients. In the yielded seeds from 2Ts and 2T5s plants, Zn concentration increased ca. 9.9 and 8.9 fold, whereas Fe raised ca. 3.9 and 5.0 fold, respectively, when compared to the original seeds non-biofortified (0Ts). In the plants from the 2nd generation (2T), leaf gas exchanges (Pn, gs, Tr) and some chl a fluorescence parameters (Fv/Fm, fe, qP, NPQ and Fv´/Fm´) where monitored 55, 73 and 91 days after germination (DAG) and compared to 0Ts values, in order to examine the effects of the biofortification solution in the photosynthetic apparatus functioning. In these days, Pn significantly increased in 2Ts and 2T5s, while gs followed an opposite drift, what provoked reductions in Tr and, concomitantly, increased in the water use efficiency, when compared to 0Ts. Additionally, the parameters related to the efficiency of photochemical energy use by the photosynthetic machinery (Fv/Fm, fe, qP and Fv´/Fm´) also raised in 2Ts and 2T5s plants. Also, these parameters declined when approaching the end of the life cycle (91st DAG) in 0Ts, but not in 2Ts and 2T5s. Thermal dissipation (given by NPQ) tend also to increase in 2Ts and 2T5s, suggesting a global reinforcement of the photosynthetic mechanisms rather than a difficulty in dealing with the captured energy, as inferred from the higher photochemical performance (Pn, fe, qP and Fv´/Fm´). Therefore, these results pointed to a higher efficiency of the photosynthetic apparatus and for a longer period in the 2Ts and 2T5s plants. Furthermore, exposure to high levels of Zn and Fe led to some morphological changes in wheat spikes. Environmental stresses may induce epigenetic changes that trigger DNA methylation. To detect changes in the methylation pattern of treated and non-treated wheat, we are using a methylation sensitive AFLP approach. We are expecting to detect different methylation states at specific loci.
|Publication status||Published - 1 Jan 2012|