The impact of cell division and cell enlargement on the evolution of fruit size in Pyrus pyrifolia.
OBJECTIVE
Dramatic increases in fruit size have accompanied the domestication of Pyrus pyrifolia. To evaluate the contribution of cell division and cell enlargement in the evolution of fruit size, the following study was conducted.


METHODS
Three wild Pyrus and 46 cultivated Pyrus pyrifolia cultivars were selected to examine cell number/size at time of pollination and at time of fruit harvest. The period of cell division was estimated by logarithmic curve of the increasing pattern of cell number, and its correlations with maturation period and final fruit size were analysed.


RESULTS
Final fruit size is directly related to the number of cells produced in the period immediately following pollination. Late-maturing cultivars are larger than earlier-maturing cultivars and this is due to an extended period of cell division.


CONCLUSIONS
The evolution of fruit size in P. pyrifolia has mainly resulted from shifts in the ability of cells to divide rather than to enlarge.
Zhang
Caixi
C
Department of Plant Science, College of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 201101, China.
Tanabe
Kenji
K
Wang
Shiping
S
Tamura
Fumio
F
Yoshida
Akira
A
Matsumoto
Kazuhiro
K
D005075:Biological Evolution; D001947:Breeding; D002455:Cell Division; D049108:Cell Enlargement; D005638:Fruit / Q000033:anatomy & histology / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D031989:Pyrus / Q000033:anatomy & histology / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*