Heat priming induces transgeneration thermo-tolerance

Effects of heat priming applied to the first generation on tolerance of the successive generation to post-anthesis high temperature stress were investigated. Compared with the progeny of non-heat primed plants (NH), the progeny of heat-primed plants (PH) presented higher grain yield, leaf photosynthesis and activities of antioxidant enzymes and lower cell membrane damage under high temperature stress. In the transcriptome profile, 1430 probes showed obvious difference in expression between PH and NH. These genes were those of signal transduction, transcription, energy, defense, and protein destination and storage, respectively. Pot experiments (25 cm in diameter and 22 cm in depth) were conducted at the Experimental Station of Nanjing Agricultural University, Nanjing, China (32˚30ʹN and 118˚42ʹE). During the first generation, wheat plants were divided into two groups: one group were not primed (N) while the other were heat-primed (P) at pre-anthesis (at a day/night temperature of 32/28˚C for two days at the seven-leaf stage and the nine-leaf stage) and post-anthesis (34/30˚C for seven days at the 10th day after anthesis). At maturity, seeds from both groups were harvested. Seedlings (the progeny generation) from each group seed were further divided two sub-groups: one was subjected to high temperature stress at a day/night temperature of 34/30˚C, while the other was set at 26/22˚C for six days from the 10th day after anthesis (DAA). During both priming and high-temperature stress, plants under different treatments were moved into sepatarate growth chambers at preset temperatures. Thereafter, four treatments were established: NC, progeny of non-primed plants without post-anthesis high temperature stress; NH, progeny of non-primed plants with post-anthesis high temperature stress; PC, progeny of primed plants without post-anthesis high temperature stress; and PH, progeny of primed plants with post-anthesis high temperature stress.