Project Number: WVA00407
CRIS Number: 0180849
Multi-State Project: W-130
FREEZE DAMAGE AND PROTECTION OF HORTICULTURAL SPECIES
Investigators: Arora, R.
Performing Department: Plant & Soil Sciences -- 1825
Start Date: 10/01/1998
Termination Date: 12/31/2001
Reporting period: 10/01/1998 to 12/31/2001
Termination Report:
Dehydrins are plant proteins that may play a critical role in stabilizing cell functions during freezing and other dehydrative stresses. Previous study in our laboratory demonstrated that the expression of a 25 kD dehydrin in leaves is associated with varying levels of freezing tolerance among F2 segregants , species, and cultivars of evergreen Rhododendron. In order to further characterize it and understand the physiological role of this dehydrin, we are currently investigating the following: 1) seasonal expression (at nonacclimated and cold acclimated state) of 25 kD dehydrin in ~ 28 Rhododendron species representing a wide array of genotypes representing varying degrees of cold hardiness (-13C to -60C) and geographical origin (Borneo to northeastern U.S.); 2) accumulation of 25 kD dehydrin in response to water stress and ABA treatments; 3) in situ localization of dehydrins (via tissue printing) in water stressed and cold acclimated Rhodondendron leaves; and 4) is 25 kD dehydrin accumulation regulated by low temperature, short photoperiods or both? Results, to date, indicate that the 25 kD dehydrin accumulates to higher levels in the cold acclimated leaves of almost all the species under investigation suggesting a universal role of this dehydrin during cold acclimation in Rhododendron. Preliminary data from tissue printing indicate that, in water stressed tissues, dehydrins accumulate more in and around the vascular tissues (mid-rib). Preliminary experiments showed no effect of ABA treatment on the hardiness and 25 kD dehydrin accumulation in leaves of two Rhododendron cultivars. ABA was applied as spray and drench in these experiments, however, potentially more effective protocols of ABA application will be employed in future studies. Experiments investigating low temperature- and / or short photoperiod-regulation of 25 kD dehydrin accumulation are underway.
Publications:
Arora, R. 2001. Cold acclimation in Rhododendron: a genetic and physiological study. In: P.H. Li and E.T. Palva (eds.), Plant Cold Hardiness: gene regulation and genetic engineering Kluwer Acedemic/Plenum Publishers, (in press)
Impact:
Establishing a role of 25 kD dehydrin in Rhododendron cold hardiness will facilitate future studies involving gene isolation and transformation of less hardy plants and potentially improving cold hardiness in rhododendrons and related species. Results from environmental regulation of this dehydrin will help unravel the fundamental mechanisms for seasonal changes in rhododendron cold hardiness and thereby allowing the development of cultural practices to manipulate cold acclimation and deacclimation.