A wound- and systemin-inducible polygalacturonase in tomato leaves

Oligogalacturonide fragments that activate defensive genes in plant leaves heretofore have been thought to be generated only by pathogen-derived pectin-degrading enzymes, because polygalacturonase (PG) activity has not been reported in leaves. Here, we report that mRNAs encoding a PG catalytic subunit protein and its regulatory (beta-subunit) protein are expressed in tomato leaves in response to wounding, systemin, and oligosaccharide elicitors. Synthesis of the two subunits in response to wounding is systemic and is accompanied by an increase in PG activity in extracts from both wounded and unwounded leaves. The finding that PG subunit mRNAs and PG enzyme activity are induced by wounding indicates that herbivore attacks can produce endogenous oligogalacturonide elicitors that may be involved in the local and systemic activation of defense responses against both herbivores and pathogens.

The effect of a structured neonatal resuscitation program on delivery room practices

PURPOSE

This study evaluated the introduction of the Neonatal Resuscitation Program (NRP) of the American Academy of Pediatrics and the American Heart Association into the delivery room of an Irish maternity hospital.

DESIGN

Prospective, controlled observational study of 51 deliveries before and 51 deliveries following the training of delivery room personnel in the NRP.

SAMPLE

Participants were 33 nurse-midwives and 11 pediatric resident physicians.

MAIN OUTCOME VARIABLE

Evaluation of postdelivery, newborn resuscitation practices.

RESULTS

The introduction of the NRP was associated with significant improvements in delivery room preparation, in the evaluation and management of the newborn infant, and in thermal protection at birth. Although there was a trend to use more free-flow oxygen following the introduction of the NRP, this was not statistically significant. Bag and mask ventilation was also used more frequently following NRP training. However, there were no significant differences in the use of endotracheal intubation, chest compressions, and medications. Fifteen of the 51 infants became hypothermic prior to the introduction of the NRP; none of the infants developed hypothermia in the post-NRP part of the study.

Systemin: a polypeptide signal for plant defensive genes

Damage to leaves of several plant species by herbivores or by other mechanical wounding induces defense gene activation throughout the plants within hours. An 18-amino acid polypeptide, called systemin, has been isolated from tomato leaves that is a powerful inducer of over 15 defensive genes when supplied to the tomato plants at levels of fmol/plant. Systemin is readily transported from wound sites and is considered to be the primary systemic signal. The polypeptide is processed from a 200-amino acid precursor called prosystemin, analogous to polypeptide hormones in animals. However, the plant prohormone does not possess typical dibasic cleavage sites, nor does it contain a signal sequence or any typical membrane-spanning regions. The signal transduction pathway that mediates systemin signaling involves linolenic acid release from membranes and subsequent conversion to jasmonic acid, a potent activator of defense gene transcription. The pathway exhibits analogies to arachidonic acid/prostaglandin signaling in animals that leads to inflammatory and acute phase responses.

delta-Tonoplast intrinsic protein defines unique plant vacuole functions

Plant cell vacuoles may have either storage or degradative functions. Vegetative storage proteins (VSPs) are synthesized in response to wounding and to developmental switches that affect carbon and nitrogen sinks. Here we show that VSPs are stored in a unique type of vacuole that is derived from degradative central vacuoles coincident with insertion of a new tonoplast intrinsic protein (TIP), delta-TIP, into their membranes. This finding demonstrates a tight coupling between the presence of delta-TIP and acquisition of a specialized storage function and indicates that TIP isoforms may determine vacuole identity.

Migration, ethnicity and environment: HIV risk factors for women on the sugar cane plantations of the Dominican Republic

OBJECTIVE

To determine risk factors for HIV infection among women living in the sugar cane plantation communities (bateyes) of a large private sugar cane company in the Dominican Republic.

DESIGN

Cross-sectional study of sexually active female volunteers living in the bateyes.

METHODS

Of 98 bateyes, 23 were randomly selected and visited by a mobile medical unit, to interview, examine and test volunteers for seroreactivity to HIV and syphilis.

RESULTS

The 490 subjects ranged in age from 16 to 72 years (median, 37 years); 53% were born in Haiti, 36% in Dominican Republic bateyes, and 12% elsewhere in the Dominican Republic; 58% had no formal education; and 87% had no income. HIV seropositivity was found in 28 women (5.7%), including 8.8% of those aged < 35 years. By logistic regression analysis, HIV infection was independently associated with age < 35 years [odds ratio (OR), 4.5; P < 0.01), being single with children (OR, 4.3; P < 0.01), more than one lifetime sex partners (OR, 3.4; P = 0.06), engaging in sex during menses (OR, 3.2; P = 0.02), and self-description as a prostitute (OR, 4.4; P = 0.05)1. For Haitian women, those coming to the Dominican Republic alone were more likely to have HIV infection than those coming with a male partner. Less than 4% of women reported condom use at last intercourse.

CONCLUSIONS

Women in the bateyes have a much higher rate of HIV infection than that estimated for women in the general population of Dominican Republic and a rate comparable to that of female sex workers in the Dominican Republic. AIDS prevention in the bateyes should address condom education and distribution as well as employment opportunities and education for women.

Intact PTH study: shipping frozen vs. unfrozen samples

DCI Laboratory, Nashville TN compared INCSTAR N-tact PTH SP Kit (INCSTAR Corp., Stillwater, MN, USA) results from renal dialysis patients analyzed on frozen versus unfrozen samples; unfrozen samples were analyzed at 24, 48, and 72 hours post-collection. There was no statistical or clinical difference in the results of the frozen samples and unfrozen samples analyzed at 24 hours. Clinics may now ship unfrozen samples if they arrive within 24 hours.

Systemin potentiates the oxidative burst in cultured tomato cells

Plants that have been wounded by insects or other herbivores may be more susceptible to infection by adventitious microbes. Wound-induced signal molecules, which serve to induce responses in the plant that retard further feeding, might also act to prepare a plant for possible pathogen attack. We have examined the effect of a wound-generated systemic messenger (systemin) on a pathogen-stimulated defense-response marker, the oxidative burst. We observed that neither systemin nor its inactive analog (A-17) was able to directly induce H2O2 biosynthesis in suspension-cultured tomato (Lycopersicon esculentum L.) cells, regardless of the duration of exposure of the cells to the two peptides. Similarly, neither systemin nor A-17 was capable of modifying an oligogalacturonide-elicited oxidative burst, as long as elicitor addition occurred within minutes of treatment with systemin or A-17. In contrast, preexposure of the cell cultures to systemin (but not to A-17) led to a time-dependent enhancement of the oligogalacturonide-elicited oxidative burst. By 12 h of exposure, the H2O2 biosynthetic capacity of systemin-treated cells exceeded that of the control cells by a factor of 16 +/- 2. A similar up-regulation by systemin of a mechanically stimulated oxidative burst was also observed. Because the systemin-induced augmentation in oxidant synthesis is quantitatively prevented by coincubation with 2 &mgr;M cycloheximide, and because the oxidative burst of oligogalacturonic acid-elicited control cells (no systemin exposure) is unaffected by preincubation with cycloheximide, we conclude that systemin enhancement of the tomato-cell oxidative burst requires protein synthesis.

Risk assessment, symptoms, and signs as predictors of vulvovaginal and cervical infections in an urban US STD clinic: implications for use of STD algorithms

OBJECTIVE

To identify clinical epidemiological correlates of cervical and vaginal infections and assess alternative algorithms, including two new reproductive tract infection (RTI) algorithms, for syndromic management of these infections.

DESIGN, SETTING AND SUBJECTS

We prospectively studied clinical manifestations and risk correlates of cervical and vaginal infections in a randomly sampled group of 779 female patients seeking evaluation for a new problem at a Seattle STD clinic.

METHODS

One experienced clinician performed standardised history, physical examination, and microscopy. Reference laboratories performed microbiological tests. Three levels of retrospective evaluation of algorithms included risk assessment and symptom review (RAS) alone; addition of speculum and bimanual examinations; and further addition of microscopy.

RESULTS

(1) Chief complaint of abnormal vaginal discharge predicted a significantly lower rate of gonorrhoea (GC) or chlamydial infection (CT) than rates observed with no complaint of vaginal discharge. Only the elicited symptom of yellow vaginal discharge (not the more common symptoms of increased or malodorous vaginal discharge) predicted GC or CT. Chief complaint of abnormal vaginal discharge itself predicted trichomoniasis (TV) and bacterial vaginosis (BV), not cervical infection. Candida albicans was strongly associated with the chief complaint of vulvar pruritus, not with the chief complaint of abnormal vaginal discharge. (2) Applying these algorithms in STD clinics only to women with the chief complaint of abnormal vaginal discharge, rather than to all women, decreases sensitivity for GC or CT, without increasing positive predictive value (PPV). Criteria for inclusion of patients have more effect on the performance of these algorithms than do the levels of evaluation used. (3) A modified World Health Organisation (WHO) algorithm applied only to patients with symptoms of vaginal discharge, involving treatment of RAS positives for cervical infection, followed by treatment of vaginal infections and cervicitis based on examination of RAS negatives and positives, had a sensitivity of 50% and PPV of 33% for cervical infection, and very low sensitivity for BV, TV, and for vulvovaginal candidiasis (VVC). (4) An RTI algorithm derived from these data, and applied to all STD patients, involving RAS and examination of all RAS negatives, provided treatment to all cases of BV and TV associated with symptoms of vaginal discharge; treatment of all VVC associated with symptoms of vulvar pruritus; treatment for GC and GT to all RAS positives (using easily elicited risk factors) and to RAS negatives with signs of cervicitis or PID. This algorithm had a sensitivity of 87% and a PPV of 33% for GC or CT in this population, with its 24% prevalence of GC or CT. The sensitivity for BV, TV, and VVC greatly exceeded that of the modified WHO algorithm. (5) A modified RTI algorithm, involving examination rather than treatment of RAS positive women, no examination of RAS negatives, decreased the sensitivity for cervical infection to 55% but increased the PPV to 51%.

CONCLUSIONS

Syndromic management of vaginal discharge offers relief of symptoms, prevention of transmission of trichomonas, and perhaps prevention of complications of BV. The 51% PPV of the modified RTI algorithm probably would warrant treatment and partner notification for GC and CT in settings with similar rates of GC and CT where more specific tests are lacking. However, as the prevalence of GC or CT decreases, the ratio of uninfected to infected who receive treatment with these algorithms would increase greatly, making the algorithms potential victims of their own success.

Reproductive tract infections in primary healthcare, family planning, and dermatovenereology clinics: evaluation of syndromic management in Morocco

OBJECTIVE

To determine where and with what symptoms women seek care for reproductive tract infections (RTI) in Morocco and to guide allocation of resources for training and treatment for RTIs.

METHODS

A primary healthcare centre (PHC), a family planning centre (FPC), and a specialty dermatovenereology clinic (SC) were selected in each of three urban areas. Women with symptoms of vaginal discharge, lower abdominal or pelvic pain, or genital lesions (genital ulcer or warts) underwent interviews, physical examinations, serological testing for human immunodeficiency virus (HIV) and syphilis, and collection of vaginal fluid for microscopic examination, and urine for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) by ligase chain reaction (LCR).

RESULTS

Over 8 months, 1238 women enrolled, including 61.8% at PHCs, 34.8% at FPCs, and 3.4% at SCs. Overall, 54% complained of vaginal discharge, of whom 8.8% had GC or CT infection and 30.1% had trichomoniasis (TV) or bacterial vaginosis (BV); 24.9% complained of lower abdominal pain with or without vaginal discharge, of whom 7.3% had GC or CT and 22.6% had TV or BV. GC or CT infections were found in 10.1% of PHC and 5.4% of FPC patients; while TV and/or BV infections were found in 28.7% and 22.8%, respectively. GC or CT infection was associated with perceived risk behaviours of the male partner (for example, belief partner is unfaithful) more often than with reported risk behaviours of the women themselves. For vaginal infections, a modified World Health Organisation (WHO) test algorithm for vaginal discharge involving risk assessment plus speculum and bimanual examination was 98.0% sensitive at PHCs and 90.8% at FPCs, with positive predictive value (PPV) of 33.4% at PHCs and 26.8% at FPCs. For GC or CT infections this algorithm was 60.6% sensitive at PHCs and 85.7% sensitive at FPCs; but PPV was only 9.9% and 9.0% respectively, little higher than the background prevalence of these infections. An RTI algorithm (Morocco specific) had comparable sensitivity and PPV for vaginal infection, and for cervical infection was less sensitive but had much higher PPV (26.9% for PHCs and 26.7% for FPCs).

CONCLUSION

Women with complaints of vaginal discharge and/or lower abdominal pain presented to PHC and FP clinics, not to SCs. PHCs and FPCs should therefore receive resources for management of vaginal discharge. Both the test algorithm and the new RTI algorithm were useful in allocating treatment for vaginal infection, but only the RTI algorithm discriminated in selecting women with cervical infection. Even with the RTI algorithm, which limited treatment for cervical infection to risk assessment positive patients with signs of cervical infection or PID, the PPV for cervical infection was low, potentially resulting in frequent overtreatment and problems of partner notification.

Wound signaling in tomato plants. Evidence that aba is not a primary signal for defense gene activation

The effects of abscisic acid (ABA) on the accumulation of proteinase inhibitors I (Inh I) and II (Inh II) in young, excised tomato (Lycopersicon esculentum L.) plants were investigated. When supplied to excised plants through the cut stems, 100 &mgr;m ABA induced the activation of the ABA-responsive le4 gene. However, under the same conditions of assay, ABA at concentrations of up to 100 &mgr;m induced only low levels of proteinase-inhibitor proteins or mRNAs, compared with levels induced by systemin or jasmonic acid over the 24 h following treatment. In addition, ABA only weakly induced the accumulation of mRNAs of several other wound-response proteins. Assays of the ABA concentrations in leaves following wounding indicated that the ABA levels increased preferentially near the wound site, suggesting that ABA may have accumulated because of desiccation. The evidence suggests that ABA is not a component of the wound-inducible signal transduction pathway leading to defense gene activation but is likely involved in the general maintenance of a healthy plant physiology that facilitates a normal wound response.

Analysis of cytokine mRNA expression following repeated exposure of mice to chemical contact and respiratory allergens

It has been shown previously that cytokine secretion patterns characteristic of the activation of discrete responses by functional subsets of T cells of type 1 and type 2, respectively, are elicited following topical exposure of BALB/c strain mice to chemical contact and respiratory allergens. In order to investigate if the differences in protein profiles are paralleled by changes in steady-state mRNA levels we have now investigated cultured draining lymph node cell (LNC) cytokine mRNA expression profiles by reverse transcriptase-polymerase chain reaction (RT-PCR) under conditions where divergent cytokine secretion is observed. Mice were exposed topically by repeated application of the respiratory allergen trimellitic anhydride (TMA) or of the contact allergen 2,4-dinitrochlorobenzene (DNCB). An elevation in the expression of mRNA for interleukin 4 (IL-4) and interleukin 10 (IL-10) by LNC from both TMA- and DNCB-treated animals was observed within 6 h of culture, reaching maximal levels after 72 h. Relative mRNA levels for both of these type 2 cytokines were considerably higher in cultured cells derived from TMA-exposed mice, compared with those from DNCB-treated animals. Transient low levels of the type 1 cytokine interferon y (IFN-gamma) were observed in response to treatment with TMA, whereas a substantial upregulation of IFN-gamma gene expression was seen from 24 h onwards in cultured LNC derived from DNCB-exposed mice. Changes in cytokine mRNA in allergen-activated LNC preceded protein production, although the kinetic profiles were similar. These data suggest that the divergent cytokine secretion profiles exhibited by mice treated by repeated topical exposure to contact and respiratory allergens are controlled primarily at the level of transcription. The RT-PCR methodology described herein may be more sensitive for the detection of cytokines expressed in low copy number, such as IL-4, where previously it has been found necessary to stimulate LNC with mitogen to elicit measurable levels of protein secretion. However, this technique was not found to offer major practical advantages when compared with protein detection methods (enzyme-linked immunosorbent assays) for the routine predictive characterization of chemicals as a function of cytokine 'fingerprinting'.

Assessment of the skin sensitization potential of topical medicaments using the local lymph node assay: an interlaboratory evaluation

The murine local lymph node assay (LLNA) is a method for the predictive identification of chemicals that have a potential to cause skin sensitization. Activity is measured as a function of lymph node cell (LNC) proliferative responses stimulated by topical application of test chemicals. Those chemicals that induce a threefold or greater increase in LNC proliferation compared with concurrent vehicle controls are classified as skin sensitizers. In the present investigations we have evaluated further the reliability and accuracy of the LLNA. In the context of an international interlaboratory trial the sensitization potentials of six materials with a history of use in topical medicaments have been evaluated: benzoyl peroxide, hydroquinone, penicillin G, streptomycin sulfate, ethylenediamine dihydrochloride, and methyl salicylate. Each chemical was analyzed in the LLNA by all five laboratories. Either the standard LLNA protocol or minor modifications of it were used. Benzoyl peroxide and hydroquinone, both human contact allergens, elicited strong LLNA responses in each laboratory. Penicillin G, another material shown previously to cause allergic contact dermatitis in humans, was also positive in all laboratories. Streptomycin sulfate induced equivocal responses, in that this material provoked a positive LLNA response in only one of the five laboratories, and then only at the highest concentration tested. Ethylenediamine dihydrochloride dissolved in a 3:1 mixture of acetone with water, or in 4:1 acetone:olive oil (one laboratory), was uniformly negative. However, limited further testing with the free base of ethylene diamine yielded a positive LLNA response when applied in acetone:olive oil (AOO). Finally, methyl salicylate, a nonsensitizing skin irritant, was negative at all test concentrations in each laboratory. Collectively these data serve to confirm that the local lymph node assay is sufficiently robust to yield equivalent results when performed independently in separate laboratories and indicate also that the LLNA is of value in assessing the skin sensitization potential of topical medicaments.

Dissemination and evaluation of AAP/AHA Neonatal Resuscitation Programme in Ireland

We evaluated the need for a structured Neonatal Resuscitation Programme (NRP) by means of a questionnaire sent to 25 Irish maternity hospitals inquiring about staff availability and current teaching structures. Having taught NRP to almost 1000 health care providers, we present a descriptive evaluation of the programme by a sample of 429 NRP participants, exploring their opinions of NRP. Our results show that midwives were responsible for newborn resuscitation at all low risk deliveries. Only 5 units (23%) had a registrar available on-site 24 hours a day, while the remaining units (77%) had to summon additional medical help from outside, in emergency situations occurring outside of normal working hours. Resuscitation equipment was checked by nurses alone (52%), or by a nurse and physician (48%), on a daily (45%), alternate days (41%) or weekly basis (14%). Although 19 units had some form of neonatal resuscitation training available, only 35% of respondents were happy with the current training structures. Almost half of the 429 providers (45%) replied to the survey. Most (85%) indicated that NRP improved their skills and confidence. Two thirds of participants found the lesson on medications the most difficult theory lesson, while 45% found endotracheal intubation the most difficult skills station. Because of the wide geographical distribution of deliveries in this country, we conclude that all perinatal professionals should be trained to perform newborn resuscitation in a coordinated, team-approach manner. NRP provides such training with a high degree of approval from Irish health care providers.

Inducible interleukin 4 (IL-4) production and mRNA expression following exposure of mice to chemical allergens

Previous investigations have indicated that different classes of chemical allergen provoke discrete immune responses in mice characterized by the development of selective cytokine secretion patterns by draining lymph node cells. It was found that, in mice exposed chronically to chemical respiratory allergens, lymph node cells produced high levels of mitogen-inducible interleukin 4 (IL-4), a cytokine necessary for the development of IgE antibody responses. In contrast, exposure of mice to contact allergens resulted in only low levels of IL-4 production. The studies described here were conducted to determine whether differentially induced expression of IL-4 messenger RNA was independent of the need for mitogen stimulation, unlike secretion of IL-4 protein. Mice were exposed to concentrations of trimellitic anhydride (TMA), a respiratory allergen, or to 2,4-dinitrochlorobenzene (DNCB), a contact allergen, under conditions of equivalent immunogenicity and where the former, but not the latter, resulted in significant production of mitogen-inducible IL-4 protein. The steady state levels of IL-4 mRNA in draining lymph nodes were measured by reverse transcription-polymerase chain reaction after a single or repeated daily application of the test chemical to the ears of chronically sensitized mice. Expression of mRNA for IL-4 was evaluated relative to the expression of a housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase. Both chemicals elicited increased steady state levels of IL-4 mRNA by draining lymph node cells compared with vehicle-treated and naive controls. However, using two different treatment protocols, a chronic and an abbreviated chronic protocol and at all times examined, the elevation in IL-4 mRNA steady state levels induced by TMA was greater than that observed with DNCB. These data provide further support for the differential stimulation by contact and respiratory chemical allergens of cytokine secretion patterns in mice and demonstrate that the divergent production of IL-4 in response to these classes of allergen is at least partly transcriptionally regulated.

Prosystemin from potato, black nightshade, and bell pepper: primary structure and biological activity of predicted systemin polypeptides

Prosystemin is the precursor protein of the 18 amino acid wound signal systemin which activates systemic defense in tomato leaves against insect herbivores (McGurl B, Pearce G, Orozco-Cardenas M, Ryan CA, Science 255 (1992) 1570-1573). Here, we report the isolation of cDNA sequences encoding prosystemin from potato (Solanum tuberosum), black nightshade (S. nigrum), and bell pepper (Capsicum annuum), all members of the Solanaceae family, using reverse-transcription polymerase chain reaction (RT-PCR). Pairwise comparisons of the predicted prosystemin proteins from the three species with tomato prosystemin and among each other indicated sequence identities ranging from 73% to 88%. The deduced systemin polypeptides were synthesized and tested for their capacities to induce the synthesis of the defensive proteinase inhibitors in tomato leaves. Potato and pepper systemins were approximately as active as tomato systemin, whereas nightshade systemin was ten-fold less active. The accumulation of proteinase inhibitor mRNA transcripts could be induced in each of these plants by treatment with the homologous systemin. As in the tomato, in potato, black nightshade, and bell pepper plants, prosystemin homologs appear to function as precursors of systemic wound signals.

A novel gene of tomato preferentially expressed in fruit encodes a protein with a Ca2+-dependent lipid-binding domain

A cDNA clone, called CLB1, was isolated from a cDNA library from tomato (Lycopersicon esculentum) and characterized. The CLB1 cDNA contains an open reading frame of 1518 bp, and encodes a putative protein of 506 amino acids with a predicted molecular mass of 54,633 Da. The deduced CLB1 amino acid sequence contains a domain that exhibits from 26% to 37% identity with the Ca2+-dependent lipid-binding domains of cytosolic phospholipase A2, protein kinase C, Rabphilin-3A, and Synaptotagmin 1 of animals. Southern blot analysis indicates that the CLB1 gene belongs to a small gene family in the tomato genome. The CLB1 mRNA is preferentially expressed in fruit tissues.

Proteinase inhibitors I and II from potatoes specifically block UV-induced activator protein-1 activation through a pathway that is independent of extracellular signal-regulated kinases, c-Jun N-terminal kinases, and P38 kinase

Solar UV irradiation is the causal factor for the increasing incidence of human skin carcinomas. The activation of the transcription factor activator protein-1 (AP-1) has been shown to be responsible for the tumor promoter action of UV light in mammalian cells. We demonstrate that proteinase inhibitor I (Inh I) and II (Inh II) from potato tubers, when applied to mouse epidermal JB6 cells, block UV-induced AP-1 activation. The inhibition appears to be specific for UV-induced signal transduction for AP-1 activation, because these inhibitors did not block UV-induced p53 activation nor did they exhibit any significant influence on epidermal growth factor-induced AP-1 transactivation. Furthermore, the inhibition of UV-induced AP-1 activity occurs through a pathway that is independent of extracellular signal-regulated kinases and c-Jun N-terminal kinases as well as P38 kinases. Considering the important role of AP-1 in tumor promotion, it is possible that blocking UV-induced AP-1 activity by Inh I or Inh II may be functionally linked to irradiation-induced cell transformation.

Myelin basic protein kinase activity in tomato leaves is induced systemically by wounding and increases in response to systemin and oligosaccharide elicitors

In response to wounding, a 48-kDa myelin basic protein (MBP) kinase is activated within 2 min, both locally and systemically, in leaves of young tomato plants. The activating signal is able to pass through a steam girdle on the stem, indicating that it moves through the xylem and does not require intact phloem tissue. A 48-kDa MBP kinase is also activated by the 18-amino acid polypeptide systemin, a potent wound signal for the synthesis of systemic wound response proteins (swrps). The kinase activation by systemin is strongly inhibited by a systemin analog having a Thr-17 --> Ala-17 substitution, which is a powerful antagonist of systemin activation of swrp genes. A 48-kDa MBP kinase activity also increases in response to polygalacturonic acid and chitosan but not in response to jasmonic acid or phytodienoic acid. In def1, a mutant tomato line having a defective octadecanoid pathway, the 48-kDa MBP kinase is activated by wounding and systemin as in the wild-type plants. This indicates that MBP kinase functions between the perception of primary signals and the DEF1 gene product. In response to wounding, the MBP kinase is phosphorylated on phosphotyrosine residues, indicating a relationship to the mitogen-activated protein kinase family of protein kinases.