Distribution of Endophyllum sempervivi ( Pucciniales ) in Ukraine

Epiphytotic development of the rust fungus Endophyllum sempervivi was recorded in May 2016 in the cemetery of Borzova village (Volhynian Region, Ukraine) on Jovibarba globifera, a host species and genus new for Ukraine. In northern Europe (Belgium, Denmark, Ireland, Netherlands, Norway, Sweden, UK), USA (northeastern states) and Canada (Ontario) E. sempervivi occurs beyond the area of natural distribution of Sempervivum and Jovibarba; however, it is apparently absent in Morocco, Spain south of the Pyrenees, Italy south of the Alps and in west Asia (the Caucasus) despite the presence of indigenous species of Sempervivum. A list of all localities in which E. sempervivi was recorded in Ukraine is provided. The article is illustrated by micrographs obtained by scanning electron microscopy.


Introduction
The genus Endophyllum Lév.comprises rusts producing only spermogonia and telia similar to spermogonia and aecia of Puccinia Pers.or Uromyces (Link) Unger.Their teliospores can be distinguished from normal aeciospores only on germination.Endophyllum sempervivi (Alb.& Schwein.) de Bary parasitizes Sempervivum L. and Jovibarba Opiz species of the Crassulaceae.Both host genera are closely related and have their origins in the European mountains, but in the Quaternary the distribution of Sempervivum expanded into northern Africa (the High Atlas Mountains of Morocco) and southwest Asia (the mountains of Turkey, the Caucasus and northern Iran) (Klein, Kadereit, 2015).Sempervivum ruthenicum Schnittsp.& C.B. Lehm., occurring in Romania, Moldova, Ukraine and southwestern Russia, is one of a few lowland species of the genus.Most records of E. sempervivi are on Sempervivum, while finds on Jovibarba are scarce (Denchev, 1995;Henderson, 2000;Mułenko et al., © Yu.Ya. TYKHONENKO, V.P. HELUTA, 20172008).Hitherto, this species was recorded in Ukraine only on S. ruthenicum.
The aim of this publication is to report a record of E. sempervivi on the new for Ukraine host genus and collate all currently known data on the localities of this fungus in Ukraine.

Materials and methods
A specimen collected in the field was labelled and dried for further treatment.Aecial teliospores mounted in water and/or lactic acid were investigated by light microscopy under Primo Star microscope and AxioVision 4.7 software, used as well for measurements of microstructures.For scanning electron microscopy samples were coated with an ultrathin coating of gold by ion beam sputtering unit JFC-1100.Images were obtained by scanning electron microscope JEOL JSM-6060 LA.
The specimen is deposited in Mycological Reference Collection of M.G.Kholodny Institute of Botany, National Academy of Sciences of Ukraine (KW-M).Spermogonia scattered amongst telia on both sides of leaves (mostly on upper side), globoid, brownish, 100-140 μm in diameter.Telia on both sides of leaves of systemically infected plants, sunken in the leaf tissue, usually cover a big part of the leaf blade.Peridium aecidioid, 0.8-1.5 mm in diameter, yellowish, opening at the top by irregular pore (Fig. 1, a, b, c).Peridium cells in cross-section irregularly roundish, with external walls 2.5-4 μm thick, almost smooth, internal 2.5-3 μm thick, densely covered with hemispherical warts.
Endophyllum sempervivi is apparently absent in Morocco, Spain south of the Pyrenees, Italy south of the Alps and in west Asia (the Caucasus) despite the presence of indigenous species of Sempervivum.
In terms of phenology, E. sempervivi is a spring species producing spermogonia and telia from April onwards (majority of its records were made in May).Infection results in a perennating mycelium which spreads through tissues of the host plant and overwinters there.On renewal of activity in the spring, the mycelium passes to the leaves and causes hypertrophy by elongation (Ashwort, 1935).The infected leaf contains more auxine than an uninfected one (Pilet, 1952), and may reach two, three or four times the normal size for the species.It is assumed that E. sempervivi produces substances which inhibit degradation of auxins, and this is the cause of the appearance of parasitized plants (Pilet, 1952).
Most frequently E. sempervivi occurs in dry habitats.Our specimen was also collected in a rather arid site, the infected host plants were growing in dry sandy soil of a village cemetery.