Aneuploidy among androgenic progeny of hexaploid triticale (XTriticosecale Wittmack).

Doubled haploids are an established tool in plant breeding and research. Of several methods for their production, androgenesis is technically simple and can efficiently produce substantial numbers of lines. It is well suited to such crops as hexaploid triticale. Owing to meiotic irregularities of triticale hybrids, aneuploidy may affect the efficiency of androgenesis more severely than in meiotically stable crops. This study addresses the issue of aneuploidy among androgenic regenerants of triticale. Plant morphology, seed set and seed quality were better predictors of aneuploidy, as determined cytologically, than flow cytometry. Most aneuploids were hypoploids and these included nullisomics, telosomics, and translocation lines; among 42 chromosome plants were nulli-tetrasomics. Rye chromosomes involved in aneuploidy greatly outnumbered wheat chromosomes; in C(0) rye chromosomes 2R and 5R were most frequently involved. While the frequency of nullisomy 2R was fairly constant in most cross combinations, nullisomy 5R was more frequent in the most recalcitrant combination, and its frequency increased with time spent in culture with up to 70% of green plants recovered late being nullisomic 5R. Given that 5R was not involved in meiotic aberrations with an above-average frequency, it is possible that its absence promotes androgenesis or green plant regeneration. Overall, aneuploidy among tested combinations reduced the average efficiency of double haploid production by 35% and by 69% in one recalcitrant combination, seriously reducing the yield of useful lines

Arabinogalactan proteins improve plant regeneration in barley (Hordeum vulgare L.) anther culture

Androgenesis-based methods of doubled haploid (DH) production show considerable variation in efficiency in different barley genotypes. Arabinogalactan proteins (AGPs) have been shown to play a key role in several developmental processes, including embryogenesis, in different plant species. In this study we investigated the effect of exogenous AGPs from gum arabic on androgenesis and the regeneration efficiency in barley anther culture. Supplementation of the induction medium with 10 mg l^{-1} gum arabic increased the total plant regeneration rate up to 2.8 times; when exposure to GA was extended to also include the pretreatment step, the regeneration rate was up to 6.6-times higher than in control. The effect of gum arabic was reversed by the Yariv reagent, an AGPs antagonist. This suggests a direct involvement of AGPs in androgenic development from barely microspores. Addition of gum arabic reduced cell mortality, increased the frequency of mitotic divisions of microspores and the number of multicellular structures (MCSs) when compared to control. The positive effect of gum arabic also included reduction in time required for the androgenic induction and substantially improved the quality of formed embryos. Observations made in this study imply a complex role of AGPs during androgenic development and confirmed the usefulness of gum arabic in production of barley androgenic plants

The Effects of Combined Abiotic and Pathogen Stress in Plants: Insights From Salinity and Pseudomonas syringae pv lachrymans Interaction in Cucumber

Plants are often challenged by abiotic and biotic stresses acting in combination and the response to combinatorial stress differs from that triggered by each factor individually. Although salinity and pathogens are major stressors limiting plant growth and productivity worldwide, their interaction is poorly understood. The reactions to pathogens overlap with those to abiotic stresses, and reactive oxygen species (ROS) and stress hormones represent central nodes in the interacting signaling pathways. Usually, abiotic stress negatively affects plant susceptibility to disease. Specific focus of this review is on cucumber plants exposed to salt stress and thereafter infected with Pseudomonas syringae pv lachrymans (Psl). We addressed this problem by discussing the changes in photochemistry, the antioxidant system, primary carbon metabolism, salicylic acid (SA) and abscisic acid (ABA) contents. Salt-treated plants were more prone to infection and this effect was determined by changes in the hormonal and redox balance as well as the carboxylate metabolism and activities of some NADPH-generating enzymes. Our detailed understanding of the interactive effects of biotic and abiotic stresses is fundamental to achieve enhanced tolerance to combination stress in agronomically important crops

Analysis of T-DNA integration and generative segregation in transgenic winter triticale (x Triticosecale Wittmack)

BACKGROUND: While the genetic transformation of the major cereal crops has become relatively routine, to date only a few reports were published on transgenic triticale, and robust data on T-DNA integration and segregation have not been available in this species. RESULTS: Here, we present a comprehensive analysis of stable transgenic winter triticale cv. Bogo carrying the selectable marker gene HYGROMYCIN PHOSPHOTRANSFERASE (HPT) and a synthetic green fluorescent protein gene (gfp). Progeny of four independent transgenic plants were comprehensively investigated with regard to the number of integrated T-DNA copies, the number of plant genomic integration loci, the integrity and functionality of individual T-DNA copies, as well as the segregation of transgenes in T(1) and T(2) generations, which also enabled us to identify homozygous transgenic lines. The truncation of some integrated T-DNAs at their left end along with the occurrence of independent segregation of multiple T-DNAs unintendedly resulted in a single-copy segregant that is selectable marker-free and homozygous for the gfp gene. The heritable expression of gfp driven by the maize UBI-1 promoter was demonstrated by confocal laser scanning microscopy. CONCLUSIONS: The used transformation method is a valuable tool for the genetic engineering of triticale. Here we show that comprehensive molecular analyses are required for the correct interpretation of phenotypic data collected from the transgenic plants

Evidences of organic acids exudation in aluminium stress responses of two Madeiran wheat (Triticum aestivum L.) landraces

Two wheat (Triticum aestivum L.) Madeiran landraces were subjected to 100 μM and 200 μM of aluminium (Al) in hydroponic culture, assessing the organic acid exudation role in plant’s responses to this metal. Samples of initial landrace populations (F0), F3 and haplodiploid lines (DH) were evaluated using standard tests: eriochrome cyanine R staining, root elongation and callose accumulation in roots. Root exudates were obtained to determine if the accumulation of malic and citric acids in hydroponic medium was a response to Al exposure. Additionally, the presence of ALMT1 gene was determined using five microsatellite markers. Standard tests confirmed that ISOP 76 was Al tolerant and ISOP 239, Al susceptible. ISOP 76, in the presence of 100 μM Al, exuded substantially more malic acid (12.87 to 43.33 mg/L), than ISOP 239 (3.65 to 7.72 mg/L). The levels of both organic acid exudation were substantially lower in ISOP 239 than in the ISOP 76. In the presence of 200 μM Al, ISOP 76 F0 shows a higher root elongation ratio (better tolerates Al), but the DH line was the one that exuded higher content of malic acid. Different gene alleles and promoters were detected in both landraces. Molecular differences could explain the observed dissimilarity in organic acid exudation response to Al stress.The authors are grateful to the Madeiran farmers providing samples of wheat landraces, and to all staff of CGR ISOPlexis Gene bank and of the Department of Biological Sciences of Alberta University for support and access to laboratory facilities. This work got the funding support from the programs INTERREG III-B, contract 05/MAC/4.1/C15 and Madeira PO 14-20, contract CASBio, refª. M1420-01-0145-FEDER-000011.info:eu-repo/semantics/publishedVersio