Respiration of turions and winter apices in aquatic carnivorous plants

Abstract

Basic respiration characteristics were measured in turions of six aquatic plant species differing greatly in their ecological and overwintering characteristics both before and after overwintering, i.e., in dormant and non-dormant state: non-carnivorous Hydrocharis morsus-ranae and Caldesia parnassifolia and carnivorous Aldrovanda vesiculosa, Utricularia australis, U. ochroleuca, and U. bremii, and in non-dormant winter apices of three Australian (sub)tropical populations of Aldrovanda and of two temperate North American Utricularia species, U. purpurea and U. radiata. Respiration rate of autumnal (dormant) turions at 20• C ranged from 0.36 to 1.3 µmol O2 kg −1 (FM) s −1 and, except for U. bremii, increased by 11-114% after overwintering. However, this increase was statistically significant only in two species. Respiration Q10 in dormant turions ranged within 1.8-2.6 and within 2.3-3.4 in spring (non-dormant) turions. Turions of aquatic plants behave as typical storage, overwintering organs with low respiration rates. No relationship was found between respiration rate of turions and overwintering strategy. In spite of their low respiration rates, turions can usually survive only from one season to another, due to their limited reserves of respiratory substrates for long periods. Contrary to true turions, respiration rates in non-dormant winter apices both in Australian Aldrovanda populations and temperate U. radiata and U. purpurea, in sprouting turions, and growing shoot apices of Aldrovanda were high and ranged from 2.1 to 3.1 µmol kg −1 (FM) s −1 , which is comparable to that in aquatic plant leaves or shoots.

Bud dormancy breaking affects respiration and energy balance of bilberry shoots in the initial stage of growth

“…In the course of dormancy induction in peach tree buds caused by shortening of photoperiod, CP activity decreased, whereas ability to transfer electrons along AP became greater [23]. In the dormant period, contribution of AP to total respiration of buds in aquatic plants varied in a wide range (50-90%) [24].…”

Tissue mineral nutrient content in turions of aquatic plants: does it represent a storage function?

“…Some subtropical or temperate Utricularia species and A. vesiculosa populations produce nondormant, quiescent shoot apices, denoted henceforth as "winter apices" (Adamec 2003b(Adamec , 2008a. However, contrary to true dormant turions, respiration rates in non-dormant winter apices of these two genera were comparable with those in growing aquatic plant shoots (Adamec 2008a).…”

“…As in typical storage organs, the dark respiration rate of turions of 6 aquatic species was rather low compared to dark respiration rates of shoots (leaves) of aquatic plants of the same or other species at a standard temperature (Adamec 2008a) -around 30-75 % lower on a fresh weight (FW) basis and 80-85 % lower per unit DW. Some subtropical or temperate Utricularia species and A. vesiculosa populations produce nondormant, quiescent shoot apices, denoted henceforth as "winter apices" (Adamec 2003b(Adamec , 2008a.…”

“…Turions of free-fl oating (non-rooted in the sediment) aquatic genera (e.g., Hydrocharis, Utricularia, Aldrovanda, Spirodela) ripen at the water surface, overwinter at the bottom, but usually germinate (sprout) at the water surface in warmer water, while those of aquatic rooted genera (e.g., Potamogeton, Caldesia, Myriophyllum) both ripen, germinate, and root at the bottom in colder water and shade (Sculthorpe 1967, Adamec 1999, 2008a. Moreover, turions of free-fl oating aquatic species differ in the mechanism of autumnal sinking and spring fl oating (Newton et al 1978, Adamec 1999, 2008a: Turions of Aldrovanda vesiculosa, Hydrocharis morsus-ranae, and Spirodela polyrhiza have developed an active mechanism of sinking and rising. It has been suggested that sinking and rising of Aldrovanda turions is caused by variable gas volume in the gas spaces of turion leaves (Adamec 1999(Adamec , 2003a.…”

“…Some subtropical or temperate Utricularia species and A. vesiculosa populations produce nondormant, quiescent shoot apices, denoted henceforth as "winter apices" (Adamec 2003b(Adamec , 2008a. However, contrary to true dormant turions, respiration rates in non-dormant winter apices of these two genera were comparable with those in growing aquatic plant shoots (Adamec 2008a). Chapin et al (1990) defi ned storage in plants as "resources that build up in the plant and can be mobilized in the future to support biosynthesis for growth or other plant functions".…”