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Formation of specialized propagules resistant to desiccation and cryopreservation in the threatened moss Ditrichum plumbicola (Ditrichales, Bryopsida).

Abstract：

BACKGROUND AND AIMS:Successful cryopreservation of bryophytes is linked to intrinsic desiccation tolerance and survival can be enhanced by pre-treatment with abscisic acid (ABA) and sucrose. The pioneer moss Ditrichum plumbicola is naturally subjected to desiccation in the field but showed unexpectedly low survival of cryopreservation, as well as a poor response to pre-treatment. The effects of the cryopreservation protocol on protonemata of D. plumbicola were investigated in order to explore possible relationships between the production in vitro of cryopreservation-tolerant asexual propagules and the reproductive biology of D. plumbicola in nature. METHODS:Protonemata were prepared for cryopreservation using a four-step protocol involving encapsulation in sodium alginate, pre-treatment for 2 weeks with ABA and sucrose, desiccation for 6 h and rapid freezing in liquid nitrogen. After each stage, protonemata were prepared for light and electron microscopy and growth on standard medium was monitored. Further samples were prepared for light and electron microscopy at intervals over a 24-h period following removal from liquid nitrogen and re-hydration. KEY RESULTS:Pre-treatment with ABA and sucrose caused dramatic changes to the protonemata. Growth was arrested and propagules induced with pronounced morphological and cytological changes. Most cells died, but those that survived were characterized by thick, deeply pigmented walls, numerous small vacuoles and lipid droplets in their cytoplasm. Desiccation and cryopreservation elicited no dramatic cytological changes. Cells returned to their pre-dehydration and cryopreservation state within 2 h of re-hydration and/or removal from liquid nitrogen. Regeneration was normal once the ABA/sucrose stimulus was removed. CONCLUSIONS:The ABA/sucrose pre-treatment induced the formation of highly desiccation- and cryopreservation-tolerant propagules from the protonemata of D. plumbicola. This parallels behaviour in the wild, where highly desiccation-tolerant rhizoids function as perennating organs allowing the moss to endure extreme environmental conditions. An involvement of endogenous ABA in the desiccation tolerance of D. plumbicola is suggested.

journal_name

Ann Bot

journal_title

Annals of botany

authors

Rowntree JK,Duckett JG,Mortimer CL,Ramsay MM,Pressel S

doi

10.1093/aob/mcm141

subject

Has Abstract

pub_date

2007-09-01 00:00:00

pages

483-96

issue

eissn

0305-7364

issn

1095-8290

pii

mcm141

journal_volume

100

pub_type

杂志文章

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Formation of specialized propagules resistant to desiccation and cryopreservation in the threatened moss Ditrichum plumbicola (Ditrichales, Bryopsida).