Choice of pollen parent affects red flesh colour in seedlings of diploidActinidia chinensis(kiwifruit)

Abstract

Flowers of diploid Actinidia chinensis (kiwifruit) were hand-pollinated with pollen from either hexaploid A. deliciosa or diploid A. chinensis males and the subsequent fruit were evaluated. Following pollination with A. deliciosa pollen, fruit set, fresh weight, dry matter content, and seed weight and number were reduced. However, the most striking effect was on fruit flesh colour: the proportion of seedlings expressing red pigmentation, the intensity of pigmentation and the anthocyanin concentration were greatly reduced. The effects on maternal fruit tissues were probably indirect consequences of a reduction in the number of fertilized ovules due to partial pollen incompatibility. Effects on seed development could be explained largely by the ploidy difference between the seed and pollen parents. Growers should be cautious about using A. deliciosa pollen to pollinate diploid A. chinensis females, especially red-fleshed cultivars.

Pollen parent effects on fruit attributes of diploidActinidia chinensis‘Hort16A’ kiwifruit

“…These increases were more than sufficient to offset reductions in FW attributable to the lower mean numbers of ovules fertilized by pollen from the higher ploidy males, resulting in the observed net increases in mean FW relative to pollination with pollen from diploid A. chinensis 'Bruce'. In the study by Seal et al (2013) with the same A. deliciosa pollen, any similar effect, if present, was insufficient to offset the impact on FW of a large (about 31%) mean reduction in the number of fertilized ovules and almost total seed abortion. In that study, there was significant variation among female seedlings in the reduction in the number of fertilized ovules following pollination by A. deliciosa relative to the number resulting from pollination by A. chinensis 'Bruce'.…”

“…The use of pollen from the tetraploid A. chinensis males or from A. deliciosa reduced the proportion of well-formed seed, and slightly delayed fruit development. In a concurrent study, when the same pollen of A. chinensis 'Bruce' and A. deliciosa was used to pollinate seedlings of diploid A. chinensis, the mean number of fertilized ovules, FW and % DM were significantly reduced following pollination with the A. deliciosa pollen (Seal et al 2013). Despite all these factors, in the present study, pollination of 'Hort16A' with pollen from the tetraploid A. chinensis or A. deliciosa males significantly increased the FW and % DM (after adjusting for differences in seed % DM) compared with pollination with pollen from A. chinensis 'Bruce'.…”

“…Kiwi Pollen and pollen from the tetraploid A. chinensis selections T1 and T2 were collected the previous spring and stored at (20 8C because the males flower too late in the season to provide fresh pollen for 'Hort16A'. Methods for the collection and preparation of pollen from flowers of 'Bruce', T1 and T2, and for hand-pollination were as described by Seal et al (2013). Pollen samples stained with lactophenol cotton blue showed high stainability.…”

“…Fruit set, FW, % DM, soluble solids concentration (SSC), fruit firmness and flesh colour at harvest were measured, as well as the total seed weight and seed % DM, using the methods described by Seal et al (2013). Ten adjacent locules (about 30% of all locules) in each of 9Á12 fruit from each handpollination treatment were scored in situ after cutting the fruit longitudinally.…”

“…Pollination of other diploid A. chinensis females with pollen from hexaploid A. deliciosa males resulted in poor pollen tube growth, a reduced rate of fertilization and eventual degeneration of the endosperm and embryo (Harvey et al 1991). Seal et al (2013) found that pollination of seedlings of diploid A. chinensis with pollen from hexaploid A. deliciosa reduced the mean FW and % DM, and the anthocyanin content of seedlings with red-fleshed fruit. These effects were associated with significant reductions in the mean number of fertilized ovules and almost total seed abortion.…”