Characterization of microspore development and pollen tube growth response to self and cross-pollination in Jeju old local citrus species

This study was conducted to investigate the seed formation potential by the evaluation of microspore development and self- and cross-compatibility through their pollen tube growth response to self and cross pollination in Jeju old local citrus species. Anther and pollen histological analyses were done to observe microspore development for three species including byungkyul, sadoogam, and dangyooza. Pollens of ten citrus species were tested for pollen viability by staining with Lugol’s solution and fluorescein diacetate. Flowers of all species were emasculated and self- and cross-pollinated just before anthesis. Pistils of nine pollinating combinations between the listed three species were collected at 1, 3, 5, 7, and 9 days after pollination for evaluation of a growth pattern of the pollen tube. Pistils of the other combinations were collected at 9 days after pollination for self- and cross-compatibility evaluation. Pistils were prepared by squashing and staining method with aniline blue. Eight pollen developmental stages were recognized and indicated normal development of microspore. These ten citrus species produced high percentage of viable pollens. Pollen tube behavior in compatible and incompatible pollination was distinguished. Pollen tube performance was largely depended on male-female combination. All of these Jeju old local citrus species were male fertile and have the ability to produce enough viable pollens for self- and cross-pollination. All evaluated citrus species were self- and cross-compatible to each other except dangyooza which was self-incompatible.