Submitted to: Acta Physiologiae Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 30, 1997
Publication Date: N/A
Interpretive Summary: The manuscript describes the latest data obtained by the authors concerning the response of the model plant Tortula ruralis to desiccation and rehydration. The authors discuss their work that suggests some desiccation- tolerant plant tissues store vital mRNAs, those that encode rehydrins, during drying for instant use upon rehydration. The authors also discuss the nature of rehydrins and the possible roles that some have in the mechanism of desiccation. These roles include ion storage and removal and anti-oxidant production. The identification and characterization of rehydrins from Tortula ruralis are the first steps in identifying gene products for use in a biotechnological approach to increasing drought resistance in crops. The importance of this approach to agriculture is extensive as, to date, normal breeding strategies have not provided crop varieties with adequate drought resistance.
Technical Abstract: Desiccation-tolerant plants can be grouped into two categories: 1) desiccation-tolerant plants whose internal water content rapidly equilibrates to the water potential of the environment and 2) the modified desiccation-tolerant plants that all employ mechanisms to retard and control the rate of water loss. Desiccation-tolerant species, in particular rthe moss Tortula ruralis, appear to utilize a tolerance strategy that combines a constitutive protection system and a rehydration-inducible recovery mechanism. The rehydration-induced recovery mechanism of Tortula ruralis relies heavily upon a change in gene expression that is mediated by post-transcriptional events. Utilizing cDNAs representing individual hydrins (proteins whose synthesis is hydration specific) and rehydrins (proteins whose synthesis is rehydration specific), it was determined that if drying rates were slow rehydrin transcripts selectively accumulate in the dried gametophytes. Biochemical analysis utilizing cesium chloride gradients, oligo dT chromatography, and FPLC established the existence of rehydrin specific messenger ribonucleoprotein particles. The identities of several rehydrins are also presented and discussed.