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PubMed1990

The CD4 associated tyrosine protein kinase p56lck is positively regulated through its site of autophosphorylation.

Antibody-mediated aggregation of the CD4 T-cell surface antigen activates bound p56lck molecules and can result in increased intracellular tyrosine protein phosphorylation. To evaluate the basis of the CD4 induced tyrosine phosphorylation signal, we have studied the ability of CD4 to regulate the function of p56lck when these two molecules are co-expressed in non-lymphoid cells. Our studies indicate that cross-linking of CD4 is capable of activation of p56lck in fibroblasts in a manner analogous to that previously reported for T-lymphocytes. They also demonstrate that replacement of the major site of autophosphorylation of p56lck (tyrosine 394) by a phenylalanine residue abolishes the ability to activate p56lck by CD4 cross-linking, implying that this residue is critical for the positive regulation of the Lck tyrosine kinase activity by CD4. Contrary to what we have previously reported for an antigen-dependent murine T-cell clone, as well as murine thymocytes, the CD4 induced activation of p56lck observed in fibroblasts does not result in marked changes in Lck tyrosine phosphorylation, suggesting that other lymphoid specific components may be required for these tyrosine phosphorylation changes.

Animals↗

PubMed1990

Immunohistochemical study of cat Pacinian corpuscles: co-localization of vimentin- and S-100 protein-like in the inner core.

The presence of vimentin and S-100 protein in cat Pacinian corpuscles of cat mesentery has been investigated immunohistochemically (streptavidin-biotin method) using monoclonal antibodies. A positive reaction for both vimentin- and S-100 protein-like was found only in the lamellae of the inner core. The presence of vimentin and the co-expression of vimentin/S-100 protein-like in sensory corpuscles is reported for the first time. The authors discuss the origin of the inner core and capsule of sensory corpuscles on the basis of their immunohistochemical characteristics.

Animals↗

PubMed1990

Premature translation termination of the pre-E1 alpha subunit of the branched chain alpha-ketoacid dehydrogenase as a cause of maple syrup urine disease in Polled Hereford calves.

Maple syrup urine disease in man and cattle is an inborn metabolic error caused by the deficiency of the branched chain alpha-ketoacid dehydrogenase. We have studied the molecular basis of the disease in Polled Hereford calves. The E1 component of branched chain alpha-ketoacid dehydrogenase was virtually undetectable by Western blot analysis of fibroblasts from an affected calf. Northern blot analysis failed to detect the E1 alpha mRNA species in the fibroblasts. Nevertheless, it was readily demonstrated by reverse transcription of RNA followed by polymerase chain reaction that the mRNA for the E1 alpha subunit was present in the cells, albeit at very low concentrations. Sequencing of the polymerase chain reaction-generated cDNA for the entire coding region of the E1 alpha subunit revealed a single base substitution at codon -6 (CAG to TAG). This mutation introduces a stop codon in the leader peptide of the E1 alpha subunit, resulting in the premature termination of translation. The mutation was verified by hybridization of the amplified cDNA fragments from two affected calves with allele-specific oligonucleotides. This finding explains the pathogenesis of maple syrup urine disease in this breed of cattle, which provides the only known animal model for the human disease. In addition, the results provide evidence for the effect of premature translation termination on reducing the steady-state mRNA level and the dependence of E1 beta protein stability on the co-expression of the E1 alpha.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed1990

Stimulation of the antigen and interleukin-2 receptors on T lymphocytes activates distinct tyrosine protein kinases.

The T cell antigen receptor complex (TCR) and the interleukin 2 (IL-2) receptor are responsible for signal transduction that results in T lymphocyte activation and proliferation. Stimulation of either the TCR or the IL-2 receptor induces an increase in tyrosine phosphorylation of several cellular proteins indicating that signal transduction by both of these receptors involves the activation of a tyrosine protein kinase. Although the tyrosine protein kinases activated by these receptors have not yet been characterized the receptors themselves are known not to contain a tyrosine protein kinase domain. To determine if these receptors are coupled to the activation of similar or distinct tyrosine protein kinases we examined the patterns and kinetics of tyrosine phosphorylation induced by stimulation of these receptors on a cloned cell line. Hut 78.3 cells co-express the TCR and the p75 IL-2 receptor. These cells were stimulated with either OKT3 antibodies, specific for the TCR, or with IL-2. Signal transduction by these receptors was found to increase the tyrosine phosphorylation of a set of proteins unique to each stimulus. The kinetics of the tyrosine phosphorylation induced by OKT3 antibodies also differed from that induced by IL-2. The OKT3-dependent tyrosine phosphorylation reached maximal levels within 2.5 min and began to decline by 5 min after stimulation. In contrast, the IL-2-induced tyrosine phosphorylation did not achieve maximal levels until 15 min after the addition of IL-2 and the proteins remained phosphorylated even after 60 min of incubation. In addition the tyrosine phosphorylations induced by OKT3 and IL-2 were not affected by prior stimulation with the other agent. These results demonstrate that the TCR and IL-2 receptor are coupled to different signal transduction pathways responsible for the independent activation of distinct tyrosine protein kinases.

Antibodies, Monoclonal↗

PubMed1986

Lectin-dependent and anti-CD3 induced cytotoxicity are preferentially mediated by peripheral blood cytotoxic T lymphocytes expressing Leu-7 antigen.

Monoclonal antibodies against the CD3 antigen and certain lectins can induce interleukin 2 dependent antigen-specific T cell clones to mediate non-antigen specific cytotoxicity. On the basis of this observation, we predicted that it may be possible to identify cytotoxic T lymphocytes (CTL) in peripheral blood without knowing the antigen specificity of these in vivo primed CTL. By using this strategy, peripheral blood lymphocytes were separated into low and high-density fractions on Percoll gradients and were tested for cytotoxic activity in the presence or absence of concanavalin A (Con A) or anti-Leu-4 antibody. Lectin-dependent cellular cytotoxicity (LDCC) and anti-CD3 induced cytotoxicity against both natural killer (NK)-insensitive and NK-sensitive targets were exclusively mediated by low-density CD3+ T lymphocytes. Additional studies indicated that low-density CD3+ T lymphocytes co-expressing Leu-7 antigen preferentially mediated this activity, although in some individuals, significant activity was also observed in the low-density T cells lacking Leu-7. In contrast, high-density CD3+ T lymphocytes and CD16+ (Leu-11+) NK cells (both Leu-7 and Leu-7+) did not mediate nonantigen-specific cytotoxicity under these conditions. The finding that NK cell-mediated cytotoxicity was unaffected by these lectins refutes the hypothesis that lectin-dependent cellular cytotoxicity is simply a result of effector and target agglutination. T cell-mediated cytotoxicity was both lectin and antibody specific. Phytohemagglutinin, Con A, and pokeweed mitogen induced cytolytic activity in the Leu-7+ T cells, whereas wheat germ agglutinin did not. Of the antibodies against T cell-associated differentiation antigens (anti-Leu-2,3,4, and 5), only anti-Leu-4 induced cytotoxicity. This anti-CD3-induced cytotoxicity was essentially completely inhibited by the presence of anti-LFA-1 or anti-CD2 monoclonal antibodies, implicating these molecules in the triggering process. A proportion of the CD3+, Leu-7+ CTL expressed HLA-DR antigens, indicating possible in vivo activation. Because previous clinical studies have indicated that lymphocytes with this phenotype may be elevated in clinical situations associated with immunosuppression and chronic viral infection, this unique subset of CD3+ T lymphocytes may represent a population of in vivo primed CTL possibly against viral antigens.

Antibodies, Monoclonal↗

PubMed1986

Abnormalities of the in vitro cellular and humoral responses to tetanus and influenza antigens with concomitant numerical alterations in lymphocyte subsets in Down syndrome (trisomy 21).

Peripheral blood leukocytes (PBL) from noninstitutionalized individuals with trisomy 21, paired with closely age-matched and/or family members as controls, were analyzed for different aspects of their cellular and humoral immune responses, and were phenotypically characterized by means of various monoclonal antibodies. Both the in vitro PBL proliferative and antibody responses to a bacterial antigen (tetanus toxoid) and to viral antigens (influenza A/Bangkok and B/Singapore) were significantly decreased in trisomy 21. In addition, bacterial and viral antigen-induced in vitro interleukin 2 (IL 2) production was markedly reduced, although mitogen (PHA)-stimulated IL 2 production was not impaired. The functional abnormalities observed in trisomy 21 PBL occur concomitantly with numerical alterations in circulating lymphocyte subsets in these same individuals. Although no difference was observed between the trisomic and control groups in the percentage of total T and B lymphocytes, a decreased level of Leu-3a + 3b-positive cells (T helper/inducer cells) and an increased level of Leu-2a-positive cells (T suppressor/cytotoxic cells) that co-expressed Leu-15 (suppressor alone) were noted.

Adolescent↗

PubMed1986

Monoclonal antibody analysis of bovine epithelial keratins. Specific pairs as defined by coexpression.

We have characterized the keratin proteins of various bovine epithelial tissues by one- and two-dimensional gel electrophoresis, coupled with the immunoblot technique using AE1, AE2, AE3, AE5, CA20, BE14, and 6.11 monoclonal antikeratin antibodies. The results indicate that all known bovine keratins can be divided into two subfamilies. The "acidic" (Type I) subfamily consists of 41-, 43-, 45-, 46-, 50-, 54-, 56-, and 56.5-kDa keratins, all of which have a pI of less than 5.6, and most of them are recognized by our AE1 antibody, whereas the "neutral-to-basic" (Type II) subfamily consists of 55-, 57-, 58-, 62-65-, 66-, and 67-kDa keratins, all of which have a pI of greater than 6.0 and are recognized by our AE3 antibody. Tissue distribution data and cell culture studies show that, within the two subfamilies, keratins with similar "size ranks" form a "pair" as defined by frequent co-expression. Furthermore, within most "keratin pairs," the basic keratin is larger than the acidic one by 8-10 kDa. These results provide further support for the concepts of "keratin subfamilies" and keratin pairs and are consistent with the possibility that the acidic and basic members of at least some keratin pairs may interact specifically during in vivo tonofilament assembly and/or function. Immunoblotting data derived from the use of several monospecific antibodies show that although the size, charge, and pattern of expression of most bovine keratins are similar to those of the human counterparts, there are important exceptions to this rule.

Animals↗

PubMed1988

LGL-1: a non-polymorphic antigen expressed on a major population of mouse natural killer cells.

Rat mAb have been raised to mouse liver-derived large granular lymphocytes (LGL). One of these mAb (4D11) binds specifically to mouse LGL and appears to recognize a non-allelic determinant on NK-active cell populations. The Ag recognized by 4D11 is expressed on LGL of all mouse strains tested, including C57BL/6 (B6), BALB/c, C3H/HeJ, and SJL/J; thus, we have provisionally called this Ag LGL-1. Analysis of various lymphoid and hemopoietic tissues has indicated that only normal tissues known to contain NK activity have 4D11+ cells. With B6 and B6 congenic strains, a positive correlation exists between the number of LGL in a sample and the percentage of 4D11 immunofluorescence-positive cells detected by flow cytometric analysis. Dual color immunofluorescence analyses indicate that some LGL-1+ cells are also stained for Ly-1 and Thy-1. A very small subset exists that is weakly positive for CD3 and LGL-1. However, virtually no cells are seen which co-express LGL-1 and Ly-2. LU activity against YAC-1 targets was increased 7- to 700-fold in LGL-1+ spleen cells obtained by cell sorting from several different strains of mice (B6, BALB/c, C3H/HeJ, SJL/J, and athymic/nude). Sorted, LGL-1- spleen cells contained little or no NK activity. Cells positively selected for LGL-1 also contained between 50 and 60% LGL by morphology. By using facilitated in vitro antibody plus C' treatments, the majority of NK activity can be depleted from both B6 spleen and liver-derived leukocyte populations enriched for NK cells. mAb 4D11 was also shown to precipitate a protein of approximately 87 kDa from the surface of enriched murine NK cells. This mAb should prove valuable for understanding the role of NK cells in the immune response.

Animals↗

PubMed1989

Review of selected lineage-directed antibodies useful in routinely processed tissues.

This review discusses several commonly used lineage-directed antibodies, including those to cytokeratins, vimentin, glial fibrillary acidic protein, neurofilaments, desmin, actin, leukocyte common antigen, and melanoma-specific antigen. Discussion is particularly directed to issues of antibody sensitivity and specificity, with several confusing and/or potentially beneficial examples of cross-lineage antigenic co-expression cited. The value of using limited panels composed of antibodies with complementary specificities is also emphasized.

Actins↗

PubMed1989

Human T cell clones present antigen.

Two human T cells clones are described which react with influenza virus hemagglutinin type H3 and synthetic peptides of H3 when presented by PBMC APC. Both T cell clones also responded to peptide Ag in the absence of additional APC suggesting that T cells can simultaneously present and respond to Ag. T cell clones could only present peptide Ag and not an appropriate strain of inactivated whole influenza virus thus indicating an inability to process Ag conventionally. Peptide presentation by T cells was dose dependent, restricted by MHC class II Ag and was dependent on the number of Ag presenting T cells per culture. Experiments with nested peptides showed that the same epitope was recognized in the presence and absence of PBMC APC. No Ag or IL-2 from the propagation procedure was carried over into assays and two-color fluorescence-activated cell sorter analysis of each clone detected no contaminating cells with the phenotype of monocytes, macrophages or B cells; in each T cell clone, all cells expressing MHC class II Ag co-expressed CD3. These date therefore provide strong evidence that human T cell clones can simultaneously present and respond to appropriate forms of Ag.

Amino Acid Sequence↗

PubMed1989

Phenotypic study of CD4+ and CD8+ lymphocyte subsets in relation to cytomegalovirus carrier status and its correlate with pokeweed mitogen-induced B lymphocyte differentiation.

A characteristic of active cytomegalovirus (CMV) infection is its suppressive effect on in vitro assays of immune function. The expression of CD11b by the Cd4+ and Cd8+ lymphocytes allows the identification of subsets with distinct regulatory functions of pokeweed mitogen (PWM) induced B cell differentiation. In order to relate that result with our previous observation that CMV carriers have significantly increased numbers of CD4+, HNK1+ and CD8+, HNK1+ lymphocytes in their peripheral blood compared with non-carriers, we performed a three-colour flow cytometric analysis of the co-expression of Cd11b and HNK1 by CD4+ and CD8+ lymphocytes obtained from 27 CMV carriers and 42 non-carriers. The differences between CMV carriers and non-carriers were significant for the CD4+, HNK1+ lymphocytes (median [5th and 95th percentiles], 59 [18 and 123 versus 24/7 and 73 per mm3, respectively; P less than 0.001) and CD8+, HNK1+ lymphocytes (59 [18 259] versus 52 [23 and 139] per mm3; P less than 0.001), but not for the CD4+, CD11b+ lymphocytes (59 [18 and 135] versus 52 [17 and 104] per mm3) and the CD8+, CD11b+ lymphocytes (85 [34 and 293] versus 82 [21 and 248] per mm3). The CD4+, HNK1+ and CD8+, HNK1+ lymphocytes that were increased in CMV carriers compared with non-carriers included mostly CD11b-, but also CD11b+ lymphocytes. After sorting CD4+ and CD8+ lymphocytes for four CMV carriers into HNK1+ and HNK1- fractions, we analyzed their regulatory functions on PWM-driven B cell Helper function to PWM-driven B cell differentiation was exclusively associated with the CD4+, HNK1- lymphocytes; the CD4+, HNK1+ generally did not show helper or suppressor activity in this assay. Both CD8+, HNK1+ and CD8+, HNK1- lymphocytes showed suppressor activity. Thus, the NHK1 marker does not constitute a phenotypical correlate for suppressor cells of PWM-driven B-cell differentiation.

Adolescent↗

PubMed1988

Intermediate filament typing in tumour diagnostics--an aid in histogenetic classification?

It is commonly accepted, that a histogenetic correlation can be established between tumour and mother tissue by means of intermediate filament typing. Recent results concerning the co-expression of different intermediate filaments within one cell, the occurrence of epithelial-specific intermediate filaments in soft tissue tumours, and the modulation of intermediate filament type expression caused by some bioactive substances and viral infections cast doubts on the general acceptance of the histogenetic classification of human tumours by intermediate filament typing. Its characterization determines only the actual morphological differentiation of the neoplastic cells and represents a valuable tool for the diagnostic assessment of the tumour under the viewpoint of the functional differentiation of its cells. A doubtless conclusion concerning the mother tissue of the neoplasia (histogenetic origin) is therefore not possible.

Animals↗

PubMed1989

Ultrastructural analysis of HNK-1+ cells in human peripheral blood and lymph nodes.

HNK-1 positive (HNK-1+) cells in human peripheral blood and lymph nodes were comparatively analysed by means of immunohistochemistry and immunoelectron microscopy. In peripheral blood, the HNK-1+ cells were grouped into large granular lymphocytes (LGLs), small lymphocytes and intermediate forms, all of which had many fine cytoplasmic processes. Except for smooth-surfaced lymphocytes, they could not be distinguished from helper/inducer T (OKT4/Leu3a) cells and suppressor/cytotoxic T (OKT8/Leu2a) cells. In double staining, HNK-1+T3- cells and HNK-1+T3+ cells could not be clearly distinguished in terms of morphology, although the former contained many LGLs. The HNK-1+ cells in the lymph nodes accumulated in the light zones of the germinal centers (GCs). These cells were small to medium-sized lymphocytes with few electron-dense granules and exclusively co-expressed helper/inducer T cell antigens (HNK-1+T4+). Their cytoplasmic projections were interwoven with those of the follicular dendritic cells which trap immune complexes for a long duration. These configurations suggest that HNK-1+T4+ cells in GCs are engaged in an immunological regulation of germinal center cells. On the other hand, large blastic HNK-1+ cells were scattered outside the GCs and some of them were in the process of mitosis. Furthermore, HNK-1+LGL-like cells with a few large electron-dense granules were rarely seen. These observations indicate that the HNK-1+ cells in the lymph nodes may proliferate outside GCs and differentiate into LGLs with a strong natural killer function.

Adult↗

PubMed1989

The expression of extracellular matrix and cytoskeleton in fused cells.

In the present paper results from our studies on the expression and regulation of the differentiated normal and transformed epithelial and fibroblastic phenotypes are reviewed. The expression of the extracellular matrix- and basement membrane-associated proteins, fibronectin and laminin, and different intermediate filament proteins were studied in different fused cells. Heterokaryons and cytoplasmic hybrids (cybrids) were formed by fusing normal or malignant epithelial cells with normal fibroblasts or malignant glial cells. No differences were observed in the expression of these phenotypic markers between unfused parental cells and the corresponding homokaryons. Thus, the fusion process itself does not cause changes in the expression of these phenotypic markers. In heterokaryons formed after fusion of normal or malignant epithelial cells with normal fibroblasts or malignant glial cells, two or even three different types of intermediate filaments could be co-expressed. Thus, no suppression of the expression of the various intermediate filaments is caused by the non-homologous parental cell. Expression of the extracellular matrix proteins, fibronectin and laminin, on the other hand, could be extinguished by cells and cytoplasts not expressing fibronectin matrix, such as transformed fibroblasts and HeLa cells. These results support the role of transacting regulatory factors controlling the expression of the different extracellular matrix proteins. Alternatively, the results can be explained by changes in the distribution and concentration of the extracellular matrix receptor proteins in the fused cells.

Animals↗

PubMed1989

CD4/Leu7 and CD8/Leu7 large granular lymphocytosis: comparative studies between NK cells and T cells.

Lymphocytes, co-expressing CD4/Leu7 and CD8/Leu7 markers respectively, taken from two patients having large granular lymphocytosis taking an indolent clinical course have been comparatively studied for function as NK cells and T cells. Both large granular lymphocytes (LGLs) were acid phosphatase positive and showed a beta-glucuronidase reaction in their cytoplasmic granules. Studies on case 1 indicated that the CD4/Leu7 lymphocytosis with LGL morphology takes a benign clinical course with mild neutropenia as well as those of CD8/Leu7 LG lymphocytosis. Both CD4/Leu7 and CD8/Leu7 LGLs behave similarly in their lack of NK activity, and manifest decreased IL-2 production in vitro and show a low IL-2 receptor expression unrelated to their T cell phenotype, but behave differently in influencing the immunoglobulin production in vitro and the ADCC activity, depending on their T cell phenotype and on the expression of Fc receptor, respectively. Furthermore, the altered Fc receptors which were undetectable by the Leul 1 antibody but were still effective for ADCC activity might be present in case 2 LGLs.

Aged↗

PubMed1989

The tissue distribution of T lymphocytes expressing different CD45 polypeptides.

The distribution of T lymphocytes expressing the different polypeptides of the leucocyte common antigen (LCA) family detected by CD45R and UCHL1 antibodies has been studied in normal lymphoid tissues. In the thymus most cortical thymocytes express UCHL1 and co-express CD4 and CD8. The more mature membrane CD3+ (mainly medullary) T cells are heterogenous and may express both UCHL1 and CD45R weakly or be restricted to display CD45R or UCHL1 alone. In the medulla both the CD45R+ and UCHL1+ subpopulations contain single positive CD4 and CD8 cells. In tonsils, germinal centre T cells are almost exclusively UCHL1+, CD4+ and a proportion also express HNK-1 (Leu 7) antigen. In the paracortical areas approximately equal numbers of CD45R+ and UCHL1+ cells are found but these separately occupy nests of cells containing one or the other type. Again, both CD45R+ and UCHL1+ cells include single CD4+ and CD8+ lymphocytes. A small proportion (less than 5%) of strongly CD45R+, UCHL1+ double-stained cells are also seen, and these probably represent recently activated lymphocytes. In the gut, small clusters of such strongly double-labelled cells are in the submuscular mucosae while cells of the lamina propria are almost exclusively UCHL1+. Many intra-epithelial lymphocytes are only weakly positive or negative for UCHL1 and appear to be CD45R-. These results are consistent with the view that expression of different CD45 polypeptides identifies successive stages of thymocyte-T-cell maturation and that following their thymic education, unprimed T lymphocytes are CD45R+, while primed memory T cells are UCHL1+. These populations occupy different microenvironments.

Antigens, Differentiation↗

PubMed1989

Lymphocyte subpopulations in Bancroftian filariasis: activated (DR+) CD8+ T cells in patients with chronic lymphatic obstruction.

To examine the relationship between lymphocyte phenotypes and states of activation in patients with Bancroftian filariasis, dual colour flow cytometry and concurrent in vitro cell culture were performed on normal individuals (NV; n = 15), and on patients with either asymptomatic microfilaraemia (MF; n = 12) or elephantiasis (CP; n = 11). In contrast to findings by others in a population with Brugian filariasis, the percentages of total B lymphocytes (CD19), T lymphocytes (CD3), helper/inducer T lymphocytes (CD4), and suppressor/cytotoxic T lymphocytes (CD8) in both patient groups were found to be within the range defined by clinically normal individuals. Furthermore, there were no differences among the groups in the expression of the IL-2 receptor (CD25) on T cells. There was, however, a significantly greater proportion (P less than 0.01) of 'activated' cytotoxic/suppressor lymphocytes (defined by co-expression of CD8 and HLA-DR) in patients with elephantiasis (16.4 +/- 8.6%) than in the MF (8.9 +/- 2.6%) or NV (8.3 +/- 2.9%) groups. Further, when the expression of this activation antigen was examined in parallel with in vitro mitogen responsiveness, an inverse correlation between the percentage of CD8+ HLA-DR+ lymphocytes and pokeweed mitogen-induced proliferation was seen (r = -0.54; P less than 0.001). These data provide further definition of the immunoregulatory abnormalities seen in human filarial infections and suggest that activated CD8+ T lymphocytes may be involved in the pathogenesis of the chronic obstructed lymphatic form of this disease.

Adult↗

PubMed2025

Whole genome duplication drives transcriptome reprogramming in response to drought in alfalfa.

Genome doubling did not enhance drought tolerance in alfalfa, but may set the stage for long-term adaptation to drought through a novel transcriptional landscape. Whole genome duplication (WGD) has been shown to enhance stress tolerance in plants. Cultivated alfalfa is autotetraploid, but diploid wild relatives are important sources of genetic variation for breeding. Investigating how WGD affects gene expression in stress conditions could provide better understanding for use of diploid genetic resources. In this work, we compared the drought response of neotetraploid plants obtained by bilateral sexual polyploidization with diploid full sibs, by measuring physiological and biochemical traits and RNA-seq. Without drought, 4x plants had lower photosynthetic potential than 2x plants per unit leaf area, but larger leaves allowed them to outperform the per leaf photosynthetic potential of 2x plants. Physiological and biochemical traits were significantly affected by drought in both 2x and 4x plants, but the differences between ploidies were small and nonsignificant. Proline levels were higher in 4x than 2x plants, both in control and drought conditions, indicating that larger cells with higher volume-to-surface ratio of 4x  plants require a higher osmolyte concentration. RNA-seq and gene network analyses showed that more genes were affected by drought at 4x than at 2x level, with downregulation of hundreds of genes involved in photosynthesis and stomatal movement at 4x level, suggesting that WGD made the 4x plants more responsive to drought. Genes involved in proline, phytormone and cell wall functions were also transcriptionally affected by drought in 4x plants. We conclude that WGD did not immediately enhance drought tolerance in alfalfa, but may set the stage for long-term adaptation to drought through a novel transcriptional landscape.

Medicago sativa↗