Differential RNA- and protein-expression profiles of cactus seeds capable of hydration memory

Abstract

2014). Differential RNA-and protein-expression proles of cactus seeds capable of hydration memory . AbstractHydration memory is a phenomenon in which a seed can tolerate discontinuous hydration periods, displaying enhanced germination after one or multiple hydration -dehydration (HD) cycles; it was described physiologically in a few cactus species around 15 years ago. Although no additional work was done on this subject, it has great biotechnological potential since its analysis would permit predictions about whether a seed can withstand discontinuous hydration; in the long run, the knowledge about its regulation might lead to induction of this resistance, so we aimed to provide an initial approach to the molecular mechanisms that underlie hydration memory. This phenomenon was reproduced successfully in our lab with Ferocactus peninsulae seeds. Using two-dimensional (2D) electrophoresis, we compared expression patterns of proteins involved in seed maturation of seeds and seedlings subjected to an HD cycle treatment. We found differential expression of several proteins possibly involved in primary metabolism, ubiquitination pathway and reserve protein availability regulation in seeds and seedlings subjected to an HD cycle. We also found differential stability of total RNA. These results strongly suggest that the differential expression of proteins is at least partially related to the hydration memory process.

Effects of wetting and drying cycles on the germination of nine species of the Chihuahuan Desert

“…For seeds of Echinocactus platyacanthus, Ferocactus pilosus, and Yucca filifera the three hydration/dehydration treatment resulted in the shortest t 50 (6 d less than the control group). This faster germination time has been shown elsewhere for the cacti Carnegiea gigantea (McDonough, 1964), Stenocereus thurberi (McDonough, 1964;Dubrovsky, 1996;Sánchez-Soto et al, 2005), S. gummosus (Dubrovsky, 1998), S. alamosensis (Sánchez-Soto et al, 2005), Cereus jamacaru (Rito et al, 2009), Mammillaria hernandezii (Santini and Martorell, 2013), and F. peninsulae (Dubrovsky, 1996;1998;López-Urrutia et al, 2014). Seed germination in arid lands is likely to be fast due to the short periods that the soil retains moisture (Jurado and Westoby, 1992;Gutterman, 1993).…”

“…For other species, germination percentage increases with increasing number of HD cycles, like in the study by Ren and Tao (2003) for Calligonum junceum and C. leucocladum, implying a cumulative effect of early imbibition (Hou et al, 1999). Seeds of some species seem to have "hydration memory" or a capacity to retain some of the physiological changes, like the differential expression of proteins (López-Urrutia et al, 2014), induced by imbibition even after temporary drying, having these seeds the same moisture content as the seeds that have never been hydrated (Dubrovsky, 1996).…”

“…The treatment of three cycles and the longer cycle treatment promoted the seed germination for four and two species, respectively, which is in agreement with Dubrovsky (1996) who found that repeated cycles of hydration/dehydration cause cumulative effect. It is possible that this process of hydration memory is related with the different protein expression as found for Ferocactus peninsulae (López-Urrutia et al, 2014).…”

“…Short rainfall may have accumulative physiological effects on seeds and this can be simulated using hydration/dehydration cycles to promote seed germination (Dubrovsky, 1996;Sánchez-Soto et al, 2005;Rito et al, 2009;Santini and Martorell, 2013;López-Urrutia et al, 2014). For seeds of Echinocactus platyacanthus, Ferocactus pilosus, and Yucca filifera the three hydration/dehydration treatment resulted in the shortest t 50 (6 d less than the control group).…”

“…However not all species have the same traits in similar environments (Budelsky and Galatowitsch, 1999). While the role of faster and higher seed germination after wet and dry cycles is likely to be a key factor in desert plant dynamics not many species have been tested (McDonough, 1964;Dubrovsky, 1996;1998;Wilson and Witkowski, 1998;Huang and Gutterman, 2000;Tobe et al, 2001;Ren and Tao, 2003;Sánchez-Soto et al, 2005;Rito et al, 2009;Santini and Martorell, 2013;López-Urrutia et al, 2014). In here we determined if germination rate and germination percentage varied in relation with wet and dry cycles for nine Chihuahuan Desert species.…”