Freezing tolerance of bread winter wheat and its relation with morphological features

In recent years there have been significant changes in weather conditions during wheat growth and development. The aim of the study was to establish the relationship between the level of freezing tolerance of bread winter wheat varieties and their morphological features. The study was conducted during 2016–2019 at the V.M. Remeslo Myronivka Institute of Wheat. 19 bread winter wheat varieties bred at Myronivka were studied. Freezing tolerance of plants was determined according to DSTU 4749:2007 which based on freezing wheat plants in chambers at -18 ºC and -20 ºC with pre-hardening in the open field. The high-frost-tolerant wheat variety Myronivska 808 was used as standard of freezing tolerance. Statistical data processing was performed according to Fisher’s test. Morphological condition of plants was estimated in autumn after vegetation dormancy onset and in spring after its restoration according to the F.M. Kuperman method. The research years were characterized by contrasting weather conditions. It was found that the most bread winter wheat varieties bred at Myronivka have high and medium level of freezing tolerance. Over the years of the research, the elongation of apical cone in the standard variety Myronivska 808 varied from 0.01 to 0.42 mm. In the varieties studied, the elongation of apical cone ranged within 0–0.10 mm (2016– 17), 0.35–0.68 (2017–18) and 0.03–0.32 mm (2018–19). According to the assessment of freezing tolerance, there have been identified valuable bread winter wheat varieties with percent of viable plants over the years of the research exceeding standard variety Myronivska 808 or being at the same level. The varieties MIP Kniazhna, Trudivnytsia myronivska, Lehenda Myronivska, Estafeta myronivska, Vezha myronivska, MIP Dniprianka, MIP Assol were high frost tolerant ones. On average, over the years of the research the varieties MIP Kniazhna, Trudivnytsia myronivska, Lehenda Myronivska, Estafeta myronivska, Vezha myronivska, MIP Dniprianka, and MIP Assol had elongation of apical cone at the level of the Myronivska 808 variety. The variation of the strength and direction of connections between the level of frost resistance and morphological indicators (plant height, length of the growth cone) determined at the time of termination and restoration of winter wheat vegetation was established. Key words: winter wheat, varieties, freezing tolerance, growth, development, apical cone.

Tibetyrus gen. nov., a new myrmecophilous Tyrini from Xizang, China (Coleoptera: Staphylinidae: Pselaphinae)

Tibetyrus formicarius Yin & Lin, gen. et sp. nov., a new myrmecophilous genus and species of the pselaphine tribe Tyrini, is described from southeastern Xizang, China. Three adults were collected in nests of a Formica ant species (Hymenoptera: Formicidae) at an altitude of 3,485 m. Tibetyrus is similar to Megatyrus Hlaváč & Nomura in sharing the basally pedunculate maxillary palpi that lack an apical cone on the fourth palpomeres. Nevertheless, it can be readily separated from the latter and all other genera of the tribe by its unique suite of morphological features as well as a highly recognizable habitus.

Influence of photoperiod on morphogenetic processes in near-isogenic lines in PPD genes of soft wheat

Aim. Investigation of the effects of contrast photoperiodic conditions and the state of the Ppd genes (dominant or recessive) on growth and morphogenetic reactions in NILs of soft winter wheat Myronivska 808 and Mercia cultivars. Methods. Experiments were carried out in field and vegetation chamber conditions. NILs were cultivated in contrast photoperiodic conditions: control group plants – in the conditions of a long photoperiod of 16 hours (LD), experimental group plants – in a short photoperiod – 9 hours (SD). The stages of organogenesis, the height of apical growth cones, the number of tillers and biomass of the above-ground part of plants were determined. Results. In our studies, we found that all NILs of both cultivars respond to a photoperiod reduction as typical long-day plants, namely: they have a two-stage of organogenesis delay in development, growth processes are inhibited (growth of the apical cone, formation of tillering shoots and accumulation of plant biomass). It was shown that NILs with the genotypes Ppd-A1a and Ppd-D1a are characterized by accelerated development due to inhibition of growth processes. Conclusions. The genes responsible for controlling the development and photoperiodic sensitivity of soft wheat plants also determine the pace of development, growth and morphogenetic reactions of common wheat plants as in LD photoperiod conditions (16 hours), as well as in SD photoperiod conditions (9 hours). Keywords: Triticum aestivum L., Ppd genes, photoperiod, stages of organogenesis, shoot apex.

Spermatological characters of Acanthobothrium crassicolle Wedl, 1855 (Tetraphyllidea, Onchobothriidae), a parasite of the common stingray Dasyatis pastinaca

We describe the spermiogenesis process and the ultrastructural characters of the spermatozoon of Acanthobothrium crassicolle by means of transmission electron microscopy, including cytochemical analysis for glycogen. Spermiogenesis in A. crassicolle begins with the formation of the differentiation zone that contains two centrioles associated with striated rootlets and an intercentriolar body. The latter is formed by one electron-dense layer. The centrioles develop into two free flagella that first grow orthogonally to a median cytoplasmic process and then undergo flagellar rotation becoming parallel to that median cytoplasmic process. After flagellar rotation only one of the flagella completes its growth and both short and long flagella undergo proximodistal fusion with the median cytoplasmic process. In the final stages of spermiogenesis, the nucleus becomes filiform and migrates into the spermatid body. Later, the ring of arched membranes constricts and the spermatozoon is liberated from the residual cytoplasm. The ultrastructural organization of the spermatozoon of A. crassicolle follows the general pattern of spermatozoa of the other Tetraphyllidea-Onchobothriidae species, but exhibits some differences. It is filiform, tapered at both extremities and lacks mitochondrion. It contains two axonemes of unequal length showing the 9 + “1“ pattern of Trepaxonemata, a nucleus, parallel cortical microtubules and electron-dense granules of glycogen. The anterior extremity of the male gamete contains a single crested body surrounding a thin and long apical cone. This type of apical cone has never been described in a tetraphyllidean spermatozoon. Another particularity is the presence of a single electron-dense microtubule at the vertex of the crested body.

Ultrastructure of the spermatozoon of Calliobothrium verticillatum (Cestoda, Tetraphyllidea, Oncobothriidae)

The ultrastructure of the spermatozoon of Calliobothrium verticillatum (Cestoda, Tetraphyllidea, Oncobothriidae) parasite of the smoothhound shark, Mustelus mustelus L. (Pisces, Carcharhiniformes), was studied by transmission electron microscopy. This spermatozoon presents five regions characterized by several ultrastructural elements: an apical cone, a crested body, two axonemes of 9 + “1” pattern, electron-dense granules, a nucleus and cortical microtubules. In the present study, three of these features were the subject of a detailed attention. The first is the presence of two axonemes, which confirms that the Tetraphyllidea, Oncobothriidae possess two axonemes whereas the Tetraphyllidea, Phyllobothriidae possess only one axoneme. The second is the presence of one crested body, a criterion homogeneous in the Tetraphyllidea but heterogeneous among the different orders of Cestoda. The third is the number and the disposition of cortical microtubules. These three criteria seem to be interesting for phylogeny.

Ultrastructural study of spermiogenesis and the spermatozoon in Catenotaenia pusilla, an intestinal parasite of Mus musculus

The ultrastructure of spermiogenesis and the mature spermatozoon in Catenotaenia pusilla (Cestoda: Catenotaeniidae) is described. Spermiogenesis is characterized by the presence of a single axoneme which grows on the outside of a cytoplasmic extension at an angle of 45°. Flagellar rotation and proximodistal fusion are produced in this process. The centrioles lack striated roots and an intercentriolar body. In the mature spermatozoon four different regions are described. The anterior extremity is capped by an apical cone and presents two helical crest-like bodies of unequal length. The axoneme, of the 9 + ‘1’ pattern of the Trepaxonemata, presents a periaxonemal sheath. The cortical microtubules form a spiral pattern at an angle of about 40° to the hypothetical spermatozoon axis. The nucleus is kidney- to horseshoe-shaped in cross section. Granules and proteinaceus walls are not observed in the spermatozoon of C. pusilla.

Comparative ultrastructure of the spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis (Cestoda, Anoplocephalidae, Inermicapsiferinae), intestinal parasites of rodents in Senegal

Spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis are filiform and tapered at both extremities. The anterior extremity exhibits an apical cone of electron-dense material and two helical ridges. The axoneme, of the 9 + "1" pattern, is surrounded over part of its length by a sheath of electron-dense material. At the posterior extremity the cytoplasm contains electron-dense material. In regions III and IV of the spermatozoa the cytoplasm is subdivided into compartments of electron-lucent material limited by irregularly spaced walls of electron-dense material. The sperm nucleus is a compact cord wound in a spiral around the axoneme. Cortical microtubules are helically arranged down the length of the spermatozoa except at the posterior extremity where they run parallel to the spermatozoon axis. In I. madagascariensis, cortical microtubules may not extend as far as the posterior extremity of the spermatozoa; the dense periaxonemal material exists in regions I to IV of the spermatozoon and the nucleus never coils more than once around the axoneme.