Effects of plant growth regulators on callus formation, growth and regeneration in axenic tissue cultures of Gracilaria tenuistipitata and Gracilaria perplexa (Gracilariales, Rhodophyta)

The effects of auxins and cytokinin on callus formation, growth and regeneration of Gracilaria tenuistipitata Chang et Xia and G. perplexa Byrne et Zuccarello (Gracilariales, Rhodophyta) are reported. Plant growth regulators (PGR) in concentrations ranging from 0.1 to 100.0 μmol of indole‐3‐acetic acid, 2,4‐dichlorophenoxyacetic acid (2,4‐D), and kinetin (K) were added to the ASP 12‐NTA solid medium (0.7% agar), and apical and intercalary segments (5 mm long) were inoculated as initial explants. K stimulated growth rates of intercalary segments of G. tenuistipitata in a linear relation, and 2,4‐D (1.0 μmol) and K (10.0 μmol) stimulated growth rates of apical and intercalary segments of G. perplexa, respectively. The simultaneous formation of apical, basal, and intermediate calluses is reported for the first time in axenic tissue cultures of red algae. With intercalary segments of G. tenuistipitata, basal callus induction rates were higher than those of apical and intermediate calluses in the majority of treatments, and auxins had stimulatory effects on the formation of all callus types. In apical segments of G. perplexa, intermediate callus formation was stimulated only by treatment with 1.0 μmol of K, while apical callus formation was stimulated by indole‐3‐acetic acid (1.0–10.0 μmol), 2,4‐D (10.0–100.0 μmol), or K (0.1 μmol). Intercalary segments of G. perplexa developed only intermediate calluses, and the majority of treatments with PGR stimulated higher rates than those presented by apical segments. Potential for regeneration (development of adventitious plantlets originated from callus cells) was higher in apical calluses than in basal and intermediate calluses developed in intercalary segments of G. tenuistipitata. Moreover, auxins and cytokinin were essential to the induction of regeneration in intermediate calluses, while specific concentrations stimulated regeneration from basal and apical calluses. Plant regeneration in G. perplexa was observed only after transferring calluses from solid to liquid medium, and the majority of treatments with PGR had stimulatory effects. Regenerating plants of G. perplexa developed tetrasporangia, and released tetraspores giving rise to adult gametophytes. Our results indicate that auxins and cytokinin have a regulatory role in the growth and morphogenesis in G. tenuistipitata and G. perplexa, and diversity of responses presented by both species is related to specific developmental systems.     

Gracilaria species (Gracilariaceae, Rhodophyta) from southeastern Australia, including a new species, Gracilaria perplexa sp. nov.: Morphology, molecular relationships and agar content

Select species of the agarophyte Gracilaria were studied from southeastern Australia. The morphology and anatomy of species is described and molecular relations are inferred based on plastid and mitochon‐drial DNA sequence data. Agar yields and qualities are determined for each species. Gracilaria chilensis, found in Tasmania and Victoria, is morphologically and molecularly similar to G. chilensis from New Zealand and Chile and has low agar yields of 11–16%. Gracilaria cliftonii from Victoria, has high crude agar yield (52%) and is molecularly uniform. Gracilaria perplexa sp. nov., known only from Botany Bay, New South Wales, has an agar yield of 39%. The agar of G. perplexa is unusual in requiring the addition of 0.1 mol L^?1 NaCl for alcohol precipitation and is cold‐water (25°C) soluble because of the very high sulfate ester content. Molecular phylogeny shows that G. perplexa is closely related to Gracilaria preissiana from western Australia, but differs from the latter in its reduced branching and narrower more terete axes.     

Behavioural evidence for body colour signaling in the fiddler crab Uca perplexa (Brachyura: Ocypodidae)

In the reproductive season, mature females of the fiddler crab Uca perplexa leave their burrows and wander about their habitat for mating. To clarify whether the fiddler crabs respond to colour or luminosity, I examined the behavioural responses of the males to the wandering females before and after the females were painted white, red, black or blue. The behaviours of the males were categorized into three types: lateral–circular wave and lateral–straight wave for courting, and repelling. Before painting, almost all of the males courted the females. After painting, significantly fewer males courted the red-, black- and blue-painted females than courted the white-painted females. These results mean that the fiddler crabs can discriminate colours or luminosity. The role of body colour as a visual signal in crab society is discussed.     

采自甘肃白龙江流域中国茶渍属地衣的三个新记录种

在对甘肃白龙江流域的茶渍属(Lecanora)地衣进行调查采集和鉴定的基础上,报道三个中国新记录种:暗灰茶渍(L.cinereofusca H.Magn),暗黄茶渍(L.flavidofusca Mll.Arg.)和颗粒茶渍(L.perplexa Brodo)。对每种给出了详尽的形态、解剖和化学特征描述,并提供了每种的外部形态照片。