title: Induced polyploidy dramatically increases the size and alters the shape of fruit in Actinidia chinensis.
abstract: OBJECTIVE
  Some otherwise promising selections of Actinidia chinensis (kiwifruit) have fruit that are too small for successful commercialization. We have therefore made the first detailed study in diploid kiwifruit of the effects of chromosome doubling induced by colchicine on fruit size, shape and crop loading.
  
  
  METHODS
  Flow cytometric analysis of young leaves and chromosome analysis of flower buds and root tips was used to confirm the stability of induced autotetraploids. Fruit weight, size and crop load were measured in the third year after planting in the field and for three consecutive years. DNA fingerprinting was used to confirm the origin of the material.
  
  
  RESULTS
  There was a very significant increase in fruit size in induced autotetraploids of different genotypes of A. chinensis. With the commercially important diploid cultivar 'Hort16A', most regenerants, Type A plants, had fruit which were much the same shape as fruit of the diploid but, at the same fruit load, were much larger and heavier. Some regenerants, Type B plants, produced fruit similar to 'fasciated' fruit. Fruit of the autotetraploids induced from three female red-fleshed A. chinensis selections were also 50-60 % larger than fruit of their diploid progenitors. The main increase in fruit dimensions was in their diameters. These improved fruit characteristics were stable over several seasons.
  
  
  CONCLUSIONS
  Chromosome doubling has been shown to increase significantly fruit size in autotetraploid A. chinensis, highlighting the considerable potential of this technique to produce new cultivars with fruit of adequate size. Other variants with differently shaped fruit were also produced but the genetic basis of this variation remains to be elucidated. Autoploids of other Actinidia species with commercial potential may also show improved fruit characteristics, opening up many new possibilities for commercial development.
authors: The New Zealand Institute for Plant & Food Research Ltd, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand. jinhu.wu@plantandfood.co.nz
authors: Jin-Hu
authors: JH
authors: Wu
authors: A Ross
authors: AR
authors: Ferguson
authors: Brian G
authors: BG
authors: Murray
authors: Yilin
authors: Y
authors: Jia
authors: Paul M
authors: PM
authors: Datson
authors: Jingli
authors: J
authors: Zhang
mesh_terms: D029042:Actinidia / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development*; D018556:Crops, Agricultural / Q000235:genetics / Q000254:growth & development; D035264:Flowers / Q000166:cytology; D005638:Fruit / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D014644:Genetic Variation; D018519:Meristem / Q000166:cytology; D018515:Plant Leaves / Q000166:cytology; D030821:Plants, Genetically Modified; D011123:Polyploidy