Chin J Plant Ecol ›› 2013, Vol. 37 ›› Issue (7): 641-649.DOI: 10.3724/SP.J.1258.2013.00066

• Research Articles • Previous Articles     Next Articles

Diadelphous stamens in Glycyrrhiza glabra: their development and adaptive significance

TIAN Run-Wei1,LU Jia-Hui1,2,3,*(),LI Xue-Yu3,YU Ying1,XIE Liang-Bi1,QIN Zhong-Li1   

  1. 1College of Life Sciences, Shihezi University, Shihezi, Xinjiang 832003, China
    2The Key Laboratory of Oasis Eco-agriculture Xinjiang Production and Construction Group, Shihezi, Xinjiang 832003, China
    3Institute of Licorice in Shihezi University, Shihezi , Xinjiang 832003, China
  • Received:2013-01-16 Accepted:2013-05-14 Online:2013-07-01 Published:2013-07-05
  • Contact: LU Jia-Hui

Abstract:

Aims The stamens of Glycyrrhiza species are diadelphous, with nine staminal filaments united at the base as a staminal sheath and separated in the upper portion of the staminal sheath. The arrayal shape of the nine stamens changes from two rows at an early stage to an inverted “V”-shaped arrangement at a later stage. Our objectives were to (1) describe development of the stamens in G. glabra (from the bud stage to full bloom) to determine differences in shape development, timing and position of stamens and (2) determine the functional role of long- and short-level stamens in the pollination processes and its adaptive significance.
Methods The development of stamens (measurement of the filament, anther, and style lengths at five developmental stages) and variability of timing and position of stamens were observed under a dissecting microscope. Scanning electron microscopy recorded pollen morphology. The vitality, quantity and chemical composition of pollen were counted and detected. In addition, the number of seeds following each pollination treatment and the pollinator behavior of insects on different stamen removal treatments were compared to examine differentiation of long- and short-level stamens.
Important findings There were differences between the long- and short-level stamens in filament length, anther size and shape early in development, but the differences disappeared when filaments elongated and mature pollen was released. The numbers of pollen grains and pollen vitality between the long- and short-level stamens were different later in development. However, no significant differences were observed in chemical composition of pollen and seed sets among different treatments. Emasculation of the long- and short-level stamens induced reductions in the visiting frequency, but the seed sets of emasculation were higher than without emasculation, which indicates that emasculation reduces the interference between stamens and stigma and improves the pollination rate. The arrayal shape of stamens changed from two rows early in time to an inverted “V”-shaped arrangement at a later stage and resulted in different quantity and vitality of pollen. This indicates that the flower of G. glabra uses fewer male resources to obtain the highest pollination efficiency and to improve male functionality.

Key words: arrangement, male function, pollination, resource allocation, stamen development