Cryopreservation of pollen of wild pineapple accessions

Abstract

Cryopreservation of pollen is an additional way to conserve many species. In particular, it can be used as an alternative strategy to preserve the genetic variation of the genus Ananas. The aim of this study was to cryopreserve pollen from wild pineapple accessions to conserve a gene pool of the genus Ananas, as well as to minimize problems of asynchronous flowering among accessions preserved in a germplasm bank. Accessions of all botanical varieties were used to investigate different protocols for freezing pollen, as well as to determine their viability in vitro/in vivo during the investigation and after freezing in liquid nitrogen. Anthers with pollen of the different accessions were dehydrated and then immersed in liquid nitrogen for periods of 24h, 60days and 120days. After freezing, the viability percentage and pollen tube length were determined. In vivo viability tests were performed through 24 pollinations involving different accessions. The results showed that the cryopreservation of pollen was efficient, attaining in vitro germination rates ranging from 8.24% to 94.25%, with average of 62.67% achieved 120days after cryopreservation and pollen tube lengths longer than 0.23mm after this same period. In the in vivo pollinations with cryopreserved grains, the seed formation rate was 70.83% for the different combinations. It was possible to cryopreserve pollen from all the pineapple accessions investigated after dehydration for 6h on silica gel, with significant in vitro germination percentages and production of viable seeds.