Overexpression of the kiwifruit SVP3 gene affects reproductive development and suppresses anthocyanin biosynthesis in petals, but has no effect on vegetative growth, dormancy, or flowering time

SVP-like MADS domain transcription factors have been shown to regulate flowering time and both inflorescence and flower development in annual plants, while having effects on growth cessation and terminal bud formation in perennial species. Previously, four SVP genes were described in woody perennial vine kiwifruit (Actinidia spp.), with possible distinct roles in bud dormancy and flowering. Kiwifruit SVP3 transcript was confined to vegetative tissues and acted as a repressor of flowering as it was able to rescue the Arabidopsis svp41 mutant. To characterize kiwifruit SVP3 further, ectopic expression in kiwifruit species was performed. Ectopic expression of SVP3 in A. deliciosa did not affect general plant growth or the duration of endodormancy. Ectopic expression of SVP3 in A. eriantha also resulted in plants with normal vegetative growth, bud break, and flowering time. However, significantly prolonged and abnormal flower, fruit, and seed development were observed, arising from SVP3 interactions with kiwifruit floral homeotic MADS-domain proteins. Petal pigmentation was reduced as a result of SVP3-mediated interference with transcription of the kiwifruit flower tissue-specific R2R3 MYB regulator, MYB110a, and the gene encoding the key anthocyanin biosynthetic step, F3GT1. Constitutive expression of SVP3 had a similar impact on reproductive development in transgenic tobacco. The flowering time was not affected in day-neutral and photoperiod-responsive Nicotiana tabacum cultivars, but anthesis and seed germination were significantly delayed. The accumulation of anthocyanin in petals was reduced and the same underlying mechanism of R2R3 MYB NtAN2 transcript reduction was demonstrated.

The roles of adsorption in hydrate precipitation

It has been well established that organic compounds with adjacent hydroxyl groups in Bayer process liquor can inhibit gibbsite precipitation by acting as seed poisons. The degree of inhibition is a function of the number and stereochemistry of the hydroxyl groups. Seed poisons generally adsorb strongly onto hydrate surfaces, implying that surface coverage is the mechanism for yield inhibition. There are examples however of organics that strongly adsorb but do not lead to yield inhibition. There is a possibility that this apparent contradiction may be an artifact of differences in conditions between the adsorption and precipitation experiments. The present work investigates the adsorption and inhibition effects of a range of compounds under strictly similar conditions to clarify the role of adsorption on yield inhibition.