Storage of Cohniella cepula (Orchidaceae) Pollinia: Fertilizing Ability and Subsequent Fruit and Seed Formation

Abstract

Pollen storage is of great importance for plant breeding and production besides an efficient means for preservation of haploid gene pool of plant genetic resources and rare or endangered species. Pollinia of Cohniella cepula were stored over 1 year at 4, −20, −70, and −196 °C. Fertilizing ability of fresh and stored (30 to 360 days) pollinia was determined by the fruit and seed formation for each treatment, as well as by the seed viability, in vitro seed germination, and seedling growth. Pollinia stored at −70 and −196 °C showed high fertilizing ability (94.4% to 100.0%) even 1 year after collection, revealing no significant differences with fresh pollinia. Seeds from all treatments showed high viability (91.2% to 94.3%) through the 2,3,5-triphenyltetrazolium chloride (TTC) reduction assay and high in vitro germination (91.7% to 97.3%). Thus, successful ultracold storage of C. cepula pollinia was feasible without any desiccation, cryoprotection, or precooling treatment before placing into an ultra freezer (−70 °C) or immersing in liquid nitrogen (LN) (−196 °C).