Authors:A. Gul Kazi, A. Rasheed, H. Bux, A.A. Napar, A. Ali, and A. Mujeeb-Kazi
The B(S) genome diploids (2n = 2x = 14) are a unique reservoir of genetic diversity that can provide wheat breeders a rich source of allelic variation for stress traits that limit productivity. Restricted in practical use essentially due to their complex chromosomal behavior, these diploids have been in limited practical usage. The classic utilization example has been the suppression activity of the Ph locus and role in alien genetic transfer aspects that has been a standard in cytogenetic manipulation studies. For applied efforts focusing on Aegilops speltoides researchers in CIMMYT initiated an ambitious program to make AABBBB(SS) synthetics and made progress by generating over 50 such synthetics. Of these 20 were available for this study in which phenology and powdery mildew screening were evaluated. Four of these 20 synthetics appeared to be useful sources for further exploitation in breeding. These were entries 6, 9, 10 and 11 suited for exploitation in pre-breeding, with positive phenological characters particularly high thousand-kernel weight and are cytologically near euploid at 2n = 6x = 42. The subtle hyper (43) and hypoploid number would not negate their applied use potential. Preference however goes to genotypes 9 and 11.
Authors:X. J. Li, X. G. Hu, T. Z. Hu, G. Li, Z. G. Ru, L. L. Zhang, and Y. M. Lang
Thinopyrum ponticum is particularly a valuable source of genes for wheat improvement. A novel wheat-Th. ponticum addition line, 1–27, was identified using cytology, SSR, ESTSSR, EST-STS and PCR-based landmark unique gene (PLUG) markers in this study. Cytological studies showed that 1–27 contained 44 chromosomes and formed 22 bivalents at meiotic metaphase I. Genomic in situ hybridization (GISH) analysis indicated that two chromosomes from Th. ponticum had been introduced into 1–27 and that these two chromosomes could form a bivalent in wheat background. Such results demonstrated that 1–27 was a disomic addition line with 42 wheat chromosomes and a pair of Th. ponticum chromosomes. One SSR marker (BARC235), one EST-STS marker (MAG3284) and 8 PLUG markers (TNAC1210, TNAC1787, TNAC1803, TNAC1805, TNAC1806, TNAC1821, TNAC1867 and TNAC1957), which were all from wheat chromosome group 7, produced the specific band in Th. ponticum and 1–27, indicating that the introduced Th. ponticum chromosomes belonging to the group 7 of wheat. Sequence analysis on specific bands from Th. ponticum and 1–27 amplified using the PLUG marker TNAC1867 further confirmed this result. The 1–27 addition line was also observed to be high resistant to powdery mildew though it is not clear if the resistance of 1–27 inherited from Th. ponticum. This study provided some useful information for effective exploitation of the source of genetic variability in wheat breeding.
): Reproductive biology of Vicia L II. Cytological and cytoembryological studies on the anther wall, microsporogenesis, pollen mitosis and development of the male gametophyta of Vicia galileae Plitm. et Zoh. - Tr. J. Biol. 23 : 269-280. (in Turkish with English
Radiofrequency radiations (RFR) are electromagnetic frequencies (EMFs) that encompass frequencies below that of visible light and above that of extremely low frequency fields. Typical man-made sources of RFR include broadcast AM/FM/TV, mobile phones and base stations, microwave ovens and radar. In this investigation, the cytological and molecular effects of RF-EMFs at 2.45 GHz, the frequency commonly used in telecommunication and microwave ovens, have been investigated in dividing root cells of five wheat cultivars following grain exposure to very short times ranging from one second to one minute. Enhanced mitotic activity and increased proportion of chromosomal abnormalities were scored in root cells as the exposure time increased. Most abnormalities are comprised of cmetaphase configurations, unoriented chromosomes at metaphase, laggards and multipolar ana-telophases indicating an action on the mitotic apparatus as well as chromosomal bridges and the formation of micronuclei indicating true clastogenic effects by the used radiation. In addition, the amplified fragment length polymorphism (AFLP) fingerprinting indicated marked DNA polymorphism among wheat cultivars and also as a result of exposure to RF-EMFs at 2.45 GHz. The results indicate remarkable cytogenetic and molecular consequence of man-made sources of RFR in plants that may lead to genetic variation. However, further research on this aspect is required to get a concrete answer for its mutagenic/carcinogenic activity.
Authors:G.C. Zhou, H.C. Shi, X.J. Yu, J.C. Yuan, Q. Guo, C.Y. Zhao, Q. Sun, and Y.P. Ke
Male sterile mutants play an important role in the utilisation of crop heterosis. Male sterile plants were found in S5 generations of maize hybrid ZH2, through continuous sib-mating by using the fertile plants in the same population, we obtained a male sterile sibling population K932MS including sterile plants K932S and a fertile plant K932F. The objective of this study was to clarify the genetic characterisation and abortion characteristics by nucleus and cytoplasm effect analyses, cytoplasm grouping, and cytological observation. The results showed that no difference was found between K932S and K932F in the vegetative growth stage, but K932S had no emerging anther or pollen grains. The segregation ratio of fertile plants to sterile plants was 1:1 in the sibling progenies, while it was 3:1 in self-crossing progenies of K932F. The sterility of K932S could be restored among reciprocal progenies when seven normal inbred lines were used as females respectively. The fertility expression of K932S crossed with 30 testers would be changed in different test-crosses and some backcross progenies. The C-type restorer Zifeng-1 (Rf4Rf4) was able to restore the fertility of K932S, and the specific PCR amplification bands of K932MS were consistent with CMSCMo17. The anther of K932S began abortion at dyad with its tapetum expanded radically and vacuolated: this induced abnormality in the shapes of both dyads and tetrads. The microspore could not develop normally, and then it collapsed and gradually disappeared. Hence, K932MS is a C-type cytoplasmic male sterile mutant with a pollen-free, stable inheritance: it has potential application value for further research.
Authors:C. Máthé, G. Vasas, G. Borbély, F. Erdődi, D. Beyer, Andrea Kiss, G. Surányi, S. Gonda, Katalin Jámbrik, and Márta M-Hamvas
This study compares the histological, cytological and biochemical effects of the cyanobacterial toxins microcystin-LR (MCY-LR) and cylindrospermopsin (CYN) in white mustard (Sinapis alba L.) seedlings, with special regard to the developing root system. Cyanotoxins induced different alterations, indicating their different specific biochemical activities. MCY-LR stimulated mitosis of root tip meristematic cells at lower concentrations (1 μg ml−1) and inhibited it at higher concentrations, while CYN had only inhibitory effects. Low CYN concentrations (0.01 μg ml−1) stimulated lateral root formation, whereas low MCY-LR concentrations increased only the number of lateral root primordia. Both inhibited lateral root development at higher concentrations. They induced lignifications, abnormal cell swelling and inhibited xylem differentiation in roots and shoots. MCY-LR and CYN induced the disruption of metaphase and anaphase spindles, causing altered cell divisions. Similar alterations could be related to decreased protein phosphatase (PP1 and PP2A) activities in shoots and roots. However, in vitro phosphatase assay with purified PP1 catalytic subunit proved that CYN in contrast to MCY-LR, decreased phosphatase activities of mustard in a non-specific way. This study intends to contribute to the understanding of the mechanisms of toxic effects of a protein phosphatase (MCY-LR) and a protein synthesis (CYN) inhibitory cyanotoxin in vascular plants.
Aegilops sharonensis (Sharon goatgrass) is a valuable source of novel high molecular weight glutenin subunits, resistance to wheat rust, powdery mildew, and insect pests. In this study, we successfully hybridized Ae. sharonensis as the pollen parent to common wheat and obtained backcross derivatives. F1 intergeneric hybrids were verified using morphological observation and cytological and molecular analyses. The phenotypes of the hybrid plants were intermediate between Ae. sharonensis and common wheat. Observations of mitosis in root tip cells and meiosis in pollen mother cells revealed that the F1 hybrids possessed 28 chromosomes. Chromosome pairing at metaphase I of the pollen mother cells in the F1 hybrid plants was low, and the meiotic configuration was 25.94 I + 1.03 II (rod). Two pairs of primers were screened out from 150 simple sequence repeat markers, and primer WMC634 was used to identified the presence of the genome of Ae. sharonensis. Sequencing results showed that the F1 hybrids contained the Ssh genome of Ae. sharonensis. The sodium dodecyl sulfate polyacrylamide gel electrophoresis profile showed that the alien high molecular weight glutenin subunits of Ae. sharonensis were transferred into the F1 and backcross derivatives. The new wheat-Ae. sharonensis derivatives that we have produced will be valuable for increasing resistance to various diseases of wheat and for improving the quality of bread wheat.
Authors:Aysen Yumurtaci, Yildiz Aydin, and Ahu Uncuoglu
Effects of salt stress on root growth, mitotic index, nuclear volume, vacuolization, nucleolar distortion and starch content were investigated in Turkish bread wheat (
L. cvs. Yildiz — salt sensitive, Dagdas — salt tolerant) and durum wheat (
L. cvs. C1252 — salt sensitive, Meramsalt tolerant) genotypes which were treated with 150 mM NaCI over a 6-day period. Salt treatment of wheat seedlings resulted in a decrease in root elongation and cell division in all genotypes at the 48 hours. According to controls, wheat root length decrease was 49% for Dagdas, 53.34% for Yildiz, 25.34% for Meram, 53.68% for C1252 at the 48 h. Mitotic index showed a more significant decrease in sensitive genotypes (1.24% for Yildiz, 0.66% for C1252 compairing to their controls 3.85% and 3.72%, respectively) of bread and durum wheat rather than tolerant ones (2.21% for Dagdas, 1.57% for Meram compairing to their controls 4.12% and 5.88%, respectively) at the 48 h of salt treatment. Calculated nuclear volume of wheat genotypes besides Dagdas showed a decline at the 48 h ranged from 1.57×10
. Vacuolization and nuclear distortion appeared on DAPI-stained preparations. There was a clear reduction in starch content in salt treated genotypes of durum wheat.