Weeks After Inoculation Research Articles

Pathogenicity of Fusarium oxysporum f. sp. lycopersici (Sacc.) Isolates in Causing Tomato Wilt Disease on Two Tomato (Solanum lycopersicum L) Varieties

Pathogenicity test of Fusarium oxysporum isolates in causing tomato wilt disease (TWD) was carried out on two tomato varieties (UC 82B and Rio-grande) in a screen house located at the Teaching and Research Farm of Federal University of Agriculture, Makurdi during 2015 cropping season. The experiment was a 2 x 11 factorial laid out in Completely Randomized Design (CRD) and replicated three times. F. oxysporum isolates tested were coded as: FoAs1, FoAs2, FoAg, FoNb, FoSb, FoAm, FoAk, FoOr, FoAd and FoUAM together with an uninoculated control. All the isolates of F. oxysporum tested were pathogenic, causing wilt on the plants from 3 weeks after inoculation (WAI), with severity of wilt been significantly higher (P≤0.05) in FoUAM. Isolates of F. oxysporum showed significant difference (P≤0.05) both in incidence and severity compared with the control. Effect of F. oxysporum isolates on some agronomic characteristics such as plant height, number of fruits, fruit weight and number of branches on the two varieties of tomato at 12 weeks after sowing (WAS) was significantly different (P≤0.05) with the control experiment. Highest severity score of 5.00 was calculated in FoUAM while the least of 4.33 was in FoSb compare with uninoculated value of 2.50. It is therefore, concluded that the two tomato varieties are pathogenic to F. oxysporum isolates and illicit disease in tomato hence reduced the yield of the crop.

Role of phytohormone on in vitro regeneration of tea [Camellia sinensis (L.) O. Kuntze

Phytohormones are small molecules present in very low concentrations in plants and provide a promising strategy to improve mass culture biotechnology due to their intrinsic role in growth, development, and survival. This study is aimed at evaluating the effect of different plant growth regulators on in vitro callus induction and shoot regeneration in tea. The experiment was conducted at Complete Randomize Design (CRD) with three replications. Callus induction and shoot regeneration was done by using Murashige & Skoog (MS) media supplemented with various concentrations and combinations of Naphthalene Acetic Acid (NAA), Benzyl Adenine (BA), and 2,4-Dichlorophenoxyacetic Acid (2,4-D). Shoot tips and nodal segments were used as explant. The highest percentage (86.51%) of callus induction was observed in the combined treatment of 2.00 milligram per litre (mg/L) BA + 1.50 mg/L 2, 4-D in 2.12 weeks. The same treatment produced the highest weight of calli, which was 0.18, 0.56, and 1.11 grams (g) for 6, 10, and 14 weeks after inoculation (WAI), respectively. The highest percentage (84.39%) of shoot induction was recorded with 2.00 mg/L BA + 2.00 mg/L NAA in 32.43 days. The maximum number (1.42, 2.46, and 4.49) and the highest length of the shoot (1.41, 3.28, and 4.61 cm) at 60, 90, and 120 DAI (days after inoculation) were also recorded from the same treatment. No callus or shoot induction was recorded in the controlled treatment. The protocol developed from the present study might be useful for the large-scale production of healthy, disease-free planting material for tea.

Relative Abundance, Emergence Profile and Parasitization of Lac Insect (<i>Kerria lacca</i>) Associated Fauna in Rangeeni Crops

Relative abundance, emergence profile and parasitization of parasitoids and predators associated with lac insect were recorded during rangeeni summer season (baisakhi) and rainy season (katki) lac crops on ber and palas under two different conditions viz., spray of fipronil + chlorothalonil and only chlorothalonil. It revealed that three parasitoids (Aprostocetus purpureus, Tachardiaephagus tachardiae, Tyndarichus clavicornis) and one predator Eublemma amabilis were abundant in both lac crops. Lac associated fauna were recorded more on lac crop sprayed with chlorothalonil only compared to fipronil + chlorothalonil on both crops on both lac hosts. Among the lac associated fauna, A. purpureus was recorded in more numbers in both crops and spray conditions. Maximum level of parasitization was recorded at the time of sexual maturity period (19 to 22 Weeks After Inoculation (WAI)) during baisakhi whereas in katki, at crop maturity period (16 to 19 WAI) on ber and palas.

OsCERK2/OsRLK10, a homolog of OsCERK1, has a potential role for chitin-triggered immunity and arbuscular mycorrhizal symbiosis in rice.

In rice, the lysin motif (LysM) receptor-like kinase OsCERK1, originally identified as the essential molecule for chitin-triggered immunity, plays a key role in arbuscular mycorrhizal (AM) symbiosis. As we previously reported, although AM colonization was largely repressed at 2 weeks after inoculation (WAI), arbuscules were observed at 5 WAI in oscerk1 mutant. Conversely, most mutant plants that defect the common symbiosis signaling pathway exhibited no arbuscule formation. Concerning the reason for this characteristic phenotype of oscerk1, we speculated that OsRLK10, which is a putative paralog of OsCERK1, may have a redundant function in AM symbiosis. The protein sequences of these two genes are highly conserved and it is estimated that the gene duplication occurred 150 million years ago. Here we demonstrated that OsCERK2/OsRLK10 induced AM colonization and chitin-triggered reactive oxygen species production in oscerk1 knockout mutant as similar to OsCERK1. The oscerk2 mutant showed a slight but significant reduction of AM colonization at 5 WAI, indicating the contribution of OsCERK2 for AM symbiosis. However, the oscerk2;oscerk1 double-knockout mutant produced arbuscules at 5 WAI as similar to the oscerk1 mutant, indicating that the redundancy of OsCERK1 and OsCERK2 did not explain the mycorrhizal colonization in oscerk1 at 5 WAI. These results indicated that OsCERK2 has a potential to regulate both chitin-triggered immunity and AM symbiosis and at least partially contributes to AM symbiosis in rice though the contribution of OsCERK2 appears to be weaker than that of OsCERK1.

In vitro shoot regeneration of Milicia excelsa (Welw.) C.C. Berg

The need for mass propagation and genetic breeding of tree species with economic importance, such as Milicia excelsa, requires an in vitro regeneration protocol. Different concentrations of Gibberellic acid (GA3) (0, 1, 2, 3 and 4 mg/L) and 6-benzylaminopurine (BAP) (0.0, 0.5, 1.0, 1.5 and 2 mg/L) were added to Murashige and Skoog medium for seed germination and shoot regeneration of the species. The treatments were laid out in completely randomised design. Each set of GA3 and BAP treatments were composed by 20 and 6 replicates, respectively. Observations made on cultured seeds include germination percentage at 4 weeks interval while shoot length, number of shoots, number of roots and leaves collected on regenerated shoots at 2 weeks interval were subjected to analysis of variance and means separated with Fisher’s protected Least Significant Difference (L.S.D) at p ≤ 0.05. Results showed that using GA3 positively influenced the seed germination as early germination occurred in the media with GA3, in comparison to the treatment without plant growth regulator (control). Nonetheless, 2.0 mg/L GA3 was observed to be the optimum, having the highest germination percentage of 30% at 4 Weeks after Inoculation (WAI). The results of the BAP effects on the shoot regeneration showed that 0.5 mg/L was the optimum for best shoot growth, having the average number of leaves (6.5), axillary shoots (1.8) and highest shoot length (3.75 cm) in comparison to the control treatment. In conclusion, these results provide insight on in vitro propagation of Milicia excelsa and the techniques employed could be adopted for its shoot multiplication. Index terms: In vitro seed germination; micropropagation; multiple shoots; moraceae.

Physiological Variations in Cucurbita moschata Duch. Ex. Poir Due to a Nigerian Strain of Moroccan Watermelon Virus: Lagenaria breviflora Isolate

Aim: Physiological variations in Cucurbita moschata due to infection with a Nigerian strain of Moroccan watermelon virus (MWMV): Lagenaria breviflora isolate was studied.
 Study Design: Randomized block design was used.
 Place and Duration of Study: Botany Department, University of Calabar, Calabar, Nigeria between March and May, 2015.
 Methodology: Seeds of C. moschata were sown, on germination inoculated with the virus and analyzed for possible variations between healthy and inoculated plants.
 Results: Results analysis revealed increase in all amino acids investigated. Highest significant (P=0.05) percentage variation in amino acids of inoculated and healthy were -40.0% for aspartic acid, -36.1% (histidine), -29.7% (proline), -28.8% (lysine), -23.3% (glysine), -16.6% (phenylalanine) and -12.6% (glutamic acid). Infection of C. moschata with a Nigerian Strain of MWMV: Lagenaria breviflora isolate caused significant decrease in leaf nitrogen and relative water content of inoculated plants compared to the healthy. Highest percentage decrease in leaf nitrogen was 40.7% at 2 weeks after inoculation (WAI) and lowest of 25.0% at 10 WAI. The virus caused decrease in relative water content of 29.6% at 6 WAI. Activity of oxidative stress enzymes: peroxidase (POD) and polyphenol oxidase (PPO) and enzymes of the oxidative pentose phosphate pathway: glucose-6-phosphate dehydrogenase (6PGdH) and 6-phosphogluconic acid dehydrogenase (G6PdH) were significantly (P=0.05) increased in infected C. moschata- MWMV plant. Enzymes activity was significantly higher in inoculated than in healthy plants at all stages of growth with decrease at later periods for both inoculated and healthy plants. Percentage increase in POD, PPO, G6PdH and 6PGdH activity due to infection at 8 WAI had values of -40.5%, -46.7%, -98.9% and -89.1% respectively.
 Conclusion: The Nigerian strain of MWMV: Lagenaria breviflora isolate caused significant variations with increase and decrease in biochemical and physiological components of C. moschata affecting its growth and yield.

Mass Propagation of Nauclea diderrichii (de Willd. & Th. Dur) Merr. Seedlings through Tissue Culture Technique

Nauclea diderrichii is a tree species of economic importance. However, its plantation establishment is limited by inadequate seedling production. Hence, there is ample scope of tissue culture for its mass propagation. Its in vitro plantlets development as affected by media strengths indicated that 100 % seed germination was obtained in full MS basal medium while the least (3.35 %) was from quarter-strength at 8 Weeks after inoculation (WAI). The effects of BAP and NAA assessed on the growth of its sub-cultured plantlets showed that highest number of leaves (17) and adventitious shoots (3) were obtained from MS basal medium supplemented with 0.1 mg/l BAP only. Whereas, highest shoot length (3.61 cm) and average number of roots (5/plantlet) were obtained from the same medium without hormone(s) at 8 WAI. Further sub-culturing into MS with 0.05 mg/l NAA resulted into plantlets having optimum shoot and massive root growth ready for acclimatization in 6 WAI. The plantlets were successfully acclimatized using coconuthusk/ topsoil mixture with 90 % survival.
 Plant Tissue Cult. & Biotech. 31(1): 51-60, 2021 (June)

Growth Evaluation of In-Vitro Propagated Embryo of Morinda Citrifolia L. Seeds

The dormant nature of Morinda citrifolia seeds is a limitation to its efficient in-vitro plantlet multiplication. Hence, the use of embryo culture for successful in-vitro culture initiation. Matured embryo of freshly collected noni seeds were cultured on Murashige and Skoog basal medium supplemented with kinetin (Kn) and Benzyl amino purine (BAP) in the range of A: control (no addition); B: 0.5 mg/l Kn+1.0 mg/l BAP; C: 1.0 mg/l Kn+2.0 mg/l Bap; D: 1.5 mg/l Kn+3.0 mg/l BAP and E: 2.0 mg/l Kn+4.0 mg/l BAP. The results at 4 weeks after inoculation (WAI) showed that germination was faster from medium A without hormone whereas highest percentage germination was obtained from both medium D and E with 80 %. Medium B and C had 65 % each while medium A gave the least (40%). The development of the plantlets showed that longest shoot (3.9 cm) from medium A was closely related to 3.58 cm from Medium B while root lengths (2.28 cm) and number of adventitious roots (26) from medium A were significantly higher than other media at 12 WAI. Highest number of nodes (2.25) obtained from medium D was comparable to Media C and B while medium A had the least at 12 WAI. Number of leaves obtained was similar between the media at 12 WAI. These results indicated that using embryo is reliable for fast in-vitro propagation and shoot development of noni plant with optimum cytokinins (0.5/1.0 mg/l Kn/BAP) application.
 Keywords: Culture initiation, Cytokinins, Embryo culture, Plantlet, Shoot development

Limitation on Growth and Yield of Phaseolus vulgaris L. Due to Telfairia Mosaic Virus

Aims: To assess limitation on growth and yield of P. vulgaris due to Telfairia mosaic virus (TeMV).
 Study Design: The study was conducted in a randomized block design.
 Place and Duration: Department of Botany, University of Calabar, Calabar, Nigeria between April and August, 2016.
 Methodology: Seeds of P. vulgaris were obtained, sorted, planted in polyethylene bags, and on germination, inoculated with TeMV, growth and yield limitation assessed at 2, 4, 6, 8 and 12 weeks after inoculation.
 Results: Results showed that the virus decreased growth of P. vulgaris resulting in yield loses. Growth parameters were severely limited by TeMV with percentage reduction in Leaf area, shoot height, number of primary shoot, petiole length and number of leaves produced of 44.5%, 52.8%, 44.0%, 44.9% and 51.45 respectively at 10 weeks after inoculation (WAI). Leaf fresh weight (38.4%) and dry weight (32.3%) were significantly (P=0.05) reduced. Relative growth rate, net assimilation rate and leaf area ratio were negatively impacted by the virus with reductions of 26.5%, 36.7% at 4 WAI and 33.5% at 12 WAI respectively. Limitation on yield due to TeMV was significant (P=0.05) with reduction in pod length of 36.9%, number of pods per plant of 36.5%, number of seeds per pod of 26.5%, number of seeds per plant of 53.3% and weight of 100 seeds of 18.5%. Limitation induced on fresh and dry weight of shoot and root, pod width, seed length and seed width was not significant.
 Conclusion: The study confirmed the threat of TeMV necessitating control of the virus on this important legume.

In-vitro development of Nauclea diderrichii (de Willd. & Th. Dur) Merrin liquid-M Smedia supplemented with benzyl amino purine (BAP) and naphthalene acetic acid (NAA)

The growth of plantlets in Temporary Immersion Bioreactor system (TIBs) relies on initial successful liquid phase transition process. The response of N. diderrichii explants was assessed in liquid-M Smedia with a view to mass produce its seedlings using TIBs. Seven treatments consisting (A) 0.0/0.0, (B) 0.0/0.1, (C) 0.1/0.0, (D) 0.2/0.1, (E) 0.3/0.2, (F) 0.4/0.3 and (G) 0.5/0.4mg/lBAP/NAA combinations were studied. Each group consist of seven replicates and group A without Growth Regulators (GR) serves as control. The results at 4 Weeks after Inoculation (WAI) showed that effects of the growth regulators were significant on shoot length and number of adventitious shoots while number of roots and leaves were closely related. Treatment E produced highest number of adventitious shoots (3.6) which was higher than 0.9 shoots from treatment G and closely related to others. Maximum number of leaves (16.6) was produced by treatment F followed by E (15.7) while the least (12) was obtained in treatment A. The highest number of roots (4.9) was obtained from treatments B, followed by E (4.3) with the lowest being recorded in C (2.43). Liquid MS medium supplemented with 0.3/0.2mg/lBAP/NAA shows some promise for plantlets generation for the purpose of multiple shoot production of N. diderrichii in TIBs.

Association of cowpea (Vigna unguiculata L. Walp.) (var. Ife Brown) with Colletotrichum destructivum O’Gara: A special reference to nutrients lost by the host

Abstract. Enyiukwu DN, Nwaogu GA, Bassey IN. 2020. Association of cowpea (Vigna unguiculata L. Walp.) (var. Ife Brown) with Colletotrichum destructivum O'Gara: A special reference to nutrients lost by the host. Cell Biol Dev 4: 41-46. Cowpea or southern pea (Vigna unguiculata L. Walp.) is an important African grain and leafy vegetable. Anthracnose caused by C. destructivum represents a major biotic drawback to the profitable production of cowpeas in the incontinent. The disease culminates in the loss of grain yield, produce quality, and nutritional values of the crop. This work assessed and quantified the nutrients lost from the aerial organs of cowpea (var. Ife Brown) challenged by anthracnose disease in the field and storage 4 weeks after inoculation (WAI) by classical and spectrometric analyses. The results showed that the disease affected the nutrient contents of the inoculated crop's aerial organs, decreasing the mean quantities of all proximate constituents and major mineral nutrients such as calcium and phosphorus in the test plant materials. Amongst the aerial organs, fat was the most depleted nutrient (36.30%), followed by protein (28.52%), carbohydrate (26.67%), and crude fiber, with 20.04%, was the least. Generally, the highest mean loss of proximate nutrients due to anthracnose disease per organ of the test crop of 27.97% was recorded in the leaf sample, followed by 22.13% in the seeds and 18.03% in the husks was the least. Similarly, the highest mean mineral loss of 42.63 mg 100 g-1 occurred in the husks, followed by the stem (26.14 mg 100 g-1), while the seed recording (15.41 mg 100 g-1) was the least. Controlling this important fungal disease of the crop will undoubtedly result in better leaf, grain, and haulm quality, which will rub off as improved farm economy and public health in the continent.

Host Suitability for Crapemyrtle Bark Scale (Acanthococcus lagerstroemiae) Differed Significantly among Crapemyrtle Species.

Simple SummaryAn exotic insect, crapemyrtle bark scale (CMBS, Acanthococcus lagerstroemiae), has spread across 14 states of the U.S. The infestation of CMBS has negatively impacted the growth, flowering, and even fruiting of some Lythraceae plants to various extent, including cultivars of Lagerstroemia indica, L. fauriei, and Punica granatum. This raises concerns that CMBS would threaten other crapemyrtle species and native Lythraceae plants. Understanding the host range and the host suitability for CMBS would help evaluate the potential risks to landscapes and other ecosystems. Information on the host suitability provides beneficial information for breeding resistant cultivars. In this study, we conducted a host range test on six Lagerstroemia species (L. caudata, L. fauriei ‘Kiowa’, L. indica ‘Dynamite’, L. limii, L. speciosa, and L. subcostata) and a native Lythraceae plant in California (California loosestrife, Lythrum californicum) over 25 weeks. The infestation of CMBS was observed on all the tested Lythraceae plants. The suitability for CMBS differed significantly among the Lagerstroemia species. Lagerstroemia limii was the most suitable, whereas L. speciosa was the least suitable. This study expands the current knowledge on the host range for CMBS. Our results suggest that L. speciosa could be utilized in developing new cultivars with low CMBS suitability.Crapemyrtle bark scale (CMBS, Acanthococcus lagerstroemiae), an invasive polyphagous sap-sucking hemipteran, has spread across 14 states of the United States since 2004. The infestation of CMBS has negatively impacted the flowering of ornamental plants and even the fruiting of some crops. Host identification is critical for determining potential risks in ecosystems and industries and helps develop strategic management. A host confirmation test was performed over 25 weeks using six Lagerstroemia species (L. caudata, L. fauriei ‘Kiowa’, L. indica ‘Dynamite’, L. limii, L. speciosa, and L. subcostata) and California loosestrife (Lythrum californicum). The 25-week observations confirmed all tested plants as the hosts. The repeated measures of analysis of variance (ANOVA; Tukey’s HSD, = 0.05) indicated that the average number of CMBS females differed significantly between L. limii and L. speciosa. The highest number of the females observed on L. limii was 576 ± 25 (mean ± SE) at 17 weeks after inoculation (WAI), while the highest number was 57 ± 15 on L. speciosa at 19 WAI. In addition, L. subcostata and L. speciosa had significantly high and low numbers of males, respectively, among the Lagerstroemia species. Our results suggest that L. speciosa could be incorporated in developing new cultivars with low CMBS suitability.

In vitro Propagation of Noni (Morinda citrifolia L.) Through Embryo Culture

The chances of shoot-regeneration from embryo culture of Morinda citrifolia L. seeds was investigated. Germination on different strengths of MS and control (Sterile distilled water) started by two weeks after inoculation (WAI). At 6 WAI, 90% of the embryo had germinated from 25% MS followed by 80% in control, 70% from 50% MS and 40% each from 100 and 75% MS. Similarly, the same MS media strengths with basal application of 2.0/1.0 mg/l BAP/Kn affected the growth of regenerated Noni-plantlets. The longest shoot length (3.46 cm) and the number of nodes (1.75) were obtained from 75% MS while the highest number of leaves (7.25) was obtained in 100% MS between 4 and 12 WAI. The lowest value for these parameters were observed in 25% MS. This showed that mature zygotic embryo is good explant for the establishment of highly viable and re-generable plantlets of Noni.
 Plant Tissue Cult. & Biotech. 30(2): 199-207, 2020 (December)

Effects of different media strengths and hormone concentrations on in-vitro regeneration of <i>Vitellaria paradoxa</i> C.F. Gaertn

The importance of Vitellaria paradoxa has necessitated its inclusion in the ongoing afforestation project which requires mass production of its seedlings. The shea-butter tree produces oil-rich seeds that are important to cosmetic and food and nutrition industries. It is a deciduous tree which could survive in the dry-savannah and help withstand desert encroachment. However, overexploitation of its timber for firewood and charcoal production made it vulnerable. In-vitro propagation of this species could be a viable means towards its mass propagation. Two plant-hormones: Gibberellic Acid (GA3) and Benzyl Amino Purine (BAP) were used to grow the plant in different combinations making up six treatments (A-F) with 6 replicates in each group. The combinations include 1.5/0, 1.5/1.0, 1.5/1.5, 2.0/0, 2.0/1.0, 2.0/1.5 mg/L of GA3/BAP, which were used to grow 2cm nodal cuttings of the V. paradoxa on half-strength Murashige and Skoog (MS) media. Treatment F (with 2.0/1.5 mg/L GA3/BAP) produced the highest number of leaves (2.4 ± 0.6, 3.2 ± 0.8) and longest shoot length (1.1 ± 0.3 cm, 1.4 ± 0.5 cm) at 4 and 8 Weeks After Inoculation (WAI), respectively. The results of this study showed that application of growth- enhancing hormones for the regeneration of important tree species could provide means for their mass propagation so as to meet the need for afforestation projects.
 Keywords: Vitellaria paradoxa, Afforestation, In-vitro propagation, Mass propagation.

Pathogenicity of fungi associated with leaf spot disease of sweet potato (Ipomea batatas L. (Lam) in Makurdi, Benue State, Nigeria

The screen house experiment was conducted to determine the pathogenicity of leaf spot fungi of sweet potato in Makurdi situated in the Southern Guinea Savannah of Nigeria. The experiment was a completely randomized design with twelve replicates. The variability in pathogenicity of four leaf spot fungi namely: Aspergillus flavus (Link), Aspergillus tamarii (Kita), Macrophomina phaseolina (Tassi), and Fusarium verticillioides (Sacc.) on sweet potato variety TIS-3164 was evaluated in the screen house using the spore suspension of the fungi at 15x 106 spores/ ml on four weeks old plants. All four isolates were pathogenic and induced necrotic symptoms on sweet potato plants. The leaf spot lesions were widest in sweet potato plants inoculated with A. tamarii (9 cm) followed by F. verticollioides (5 cm), A. flavus (4 cm) and M. phaseolina (3.20 cm). Sweet potato plants inoculated with spore suspension of the test fungi recorded significantly (P < 0.05) lower number of leaves with sweet potato plants inoculated with F. verticillioides recording the least number of leaves (30.75). At 4weeks after planting (WAP), the application of the spore suspension of A. tamarii produced significantly lower leaf area of 5.56cm2. At 4 weeks after inoculation (WAI), percentage leaf defoliation was highest on sweet potato plants inoculated with A. flavus (44.50 %) and least when sweet potato plants were inoculated with M. phaseolina (34.30 %). The inoculation of the sweet potato plants with all test fungi had no significant effect on the vine length. The study demonstrated the pathogenicity of all four test fungi on sweet potato.

The relationship between SPAD chlorophyll and disease severity index in Ganoderma-infected oil palm seedlings

Establishment of disease in oil palm seedlings through artificial inoculation of Ganoderma are widely used for studies of various aspects of plant pathology, including epidemiology, etiology, disease resistance, host-parasite interaction and disease control. The estimation of chlorophyll content in the infected seedlings possibly could provide a good indicator for degree of disease or infection, and changes during pathogenesis. Thus, the objective of this study was to evaluate the relationship between disease severity index (DSI) and chlorophyll content in Ganoderma infected oil palm seedlings. Three-month-old oil palm seedlings were infected with Ganoderma inoculum on rubber wood block (RWB), where 44 isolates of Ganoderma were tested. Disease severity index (DSI) and chlorophyll content using a single-photon avalanche diode (SPAD) meter were recorded at 4 weeks interval for a period of 24 weeks after inoculation (WAI). Pearson's correlation analysis and regression analysis were performed to evaluate the relationship between the variables. It was found that the relationship between DSI and SPAD chlorophyll value was inversely proportional (R = -0.92) in a linear trend (R2 = 0.85). Furthermore, the increasing trend of the DSI across the weeks were fitted in a quadratic model (R2 = 0.99). In contrast, the SPAD chlorophyll value declined in a linear trend (R2 = 0.98). The SPAD chlorophyll value could be considered as a better alternative over the DSI as the SPAD chlorophyll value was strongly related to DSI, as well as able to detect physiological changes in the infected oil palm seedlings at the early stages of pathogenesis.&#x0D; J Bangladesh Agril Univ 17(3): 355–358, 2019

Embryogenesis of 'albescens'-type of oil palm (&lt;i&gt;Elaeis guineensis&lt;/i&gt; Jacq.) in Eeuwens medium

The growth response of zygotic embryos of 'Albescens'- type of 'tenera' oil palm (Elaeis guineensis Jacq.) using Eeuwens medium, supplemented with 1-Naphthalene Acetic Acid (NAA) and 6-Benzylaminopurine (BAP) was investigated. The respective concentrations (0.00 mg/L, 0.05 mg/L, 0.10 mg/L) of NAA and BAP were used singly and in combination. Zygotic embryos extracted from the 'Tenera-albescens' type of oil palm were sterilized and inoculated in Eeuwens media containing the various combinations of growth regulators. The cultures were incubated in the dark room at 26oC, 50-60% relative humidity and later transferred to the light room at 26oC, 50-60% relative humidity at 16 hr photoperiod. Subcultures were carried out at intervals of 4 weeks. Data were collected on days to shoot and root emergence, shoot length at 3 weeks after inoculation (WAI), root length and plant height at 4, 6, 8 and 10 WAI, number of leaves and roots at 10 WAI. The results showed that the concentrations of NAA and BAP singly and in combinations had significant (p &lt; 0.05) effect on in vitro plant regeneration and plantlet development. However, synergistic effect of the two plant growth regulators as supplements were optimal for all growth parameters measured.Keywords: Elaeis guineensis, 'Albescens', dormancy, germination, Eeuwens, in vitro

Resistance response of fifteen sweet potato genotypes to scab disease (Sphaceloma batatas) in two growing sites in East Nusa Tenggara, Indonesia

Mau YS. 2018. Resistance response of fifteen sweet potato genotypes to scab disease (Sphaceloma batatas) in two growing sites in East Nusa Tenggara, Indonesia. Trop Drylands 2: 5-11. Field experiments were carried out in two growing locations involving potential sweet potato clones from East Nusa Tenggara Province, Indonesia to: (i) evaluate scab resistance levels of the sweet potato clones, and (ii) identify sweet potato clones with good resistance level to scab disease. The experiment was carried out in the fields employing a Randomized Block Design with a mono-factorial treatment design in each location. The treatment assigned was sweet potato genotype, each consisted of two replicates. The variables observed were disease severity that was assessed at 2, 4, 6, and 8 weeks after inoculation (WAI), which then was used to calculate the Area Under the Disease Progress Curve (AUDPC) of the disease severity. The ANOVA of AUDPC was used to determine the treatment effect, and the disease severity at 8 WAI was used to assess scab resistance level of the sweet potato genotypes tested. The study results showed highly significant differences of disease severities among the tested sweet potato genotypes within each trial location. The majority of the genotypes tested were classified "resistant" or "moderately resistant" to scab disease, except the check clone SLM-01 and KRA-01 that were, respectively, "susceptible" and "moderately susceptible" to scab disease. The majority of sweet potato genotypes evaluated were consistent in their resistance performance in the two trial locations.

Analysis of nodule senescence in pea (Pisum sativum L.) using laser microdissection, real-time PCR, and ACC immunolocalization

A delay in the senescence of symbiotic nodules could prolong active nitrogen fixation, resulting in improved crop yield and a reduced need for chemical fertilizers. The molecular genetic mechanisms underlying nodule senescence have not been extensively studied with a view to breeding varieties with delayed nodule senescence. In such studies, plant mutants with the phenotype of premature degradation of symbiotic structures are useful models to elucidate the genetic basis of nodule senescence. Using a dataset from transcriptome analysis of Medicago truncatula Gaertn. nodules and previous studies on pea (Pisum sativum L.) nodules, we developed a set of molecular markers based on genes that are known to be activated during nodule senescence. These genes encode cysteine proteases, a thiol protease, a bZIP transcription factor, enzymes involved in the biosynthesis of ethylene (ACS2 for ACC synthase and ACO1 for ACC oxidase) and ABA (AO3 for aldehyde oxidase), and an enzyme involved in catabolism of gibberellins (GA 2-oxidase). We analyzed the transcript levels of these genes in the nodules of two pea wild-types (cv. Sparkle and line Sprint-2) and two mutant lines, one showing premature nodule senescence (E135F (sym13)) and one showing no morphological signs of symbiotic structure degradation (Sprint-2Fix− (sym31)). Real-time PCR analyses revealed that all of the selected genes showed increased transcript levels during nodule aging in all phenotypes. Remarkably, at 4 weeks after inoculation (WAI), the transcript levels of all analyzed genes were significantly higher in the early senescent nodules of the mutant line E135F (sym13) and in nodules of the mutant Sprint-2Fix− (sym31) than in the active nitrogen-fixing nodules of wild-types. In contrast, the transcript levels of the same genes of both wild-types were significantly increased only at 6 WAI. We evaluated the expression of selected markers in the different histological nodule zones of pea cv. Sparkle and its mutant line E135F (sym13) by laser capture microdissection analysis. Finally, we analyzed ACC by immunolocalization in the nodules of both wild-type pea and their mutants. Together, the results indicate that nodule senescence is a general plant response to nodule ineffectiveness.

CENTELLA ASIATICA EXTRACT INCREASED ON THE LEVEL OF INTERLEUKIN 6 (IL-6) IN MICE

Salmonellosis is still problem in many developing countries including Indonesia. Themain problem in controlling and handling the disease is that only few antibiotics are availableto cure the disease. In addition, the prolonged use of such antibiotics often lead to bacterialresistant against the antibiotics. A herbal drugs such as Centella asiatica (in Indonesia isknown as pegagan) contains triterphenoid saphonins which acts as immunostimulant capableof enhancing the phagocytic activity of macrophages. However, no study has been conductedto investigate the use pegagan in activating macrophage of mice infected with Salmonellatyphi. A study was therefore conducted to find out the ability of Cantella asiatica inenhancing on the level interluekine (IL)-6 following challenge with Salmonella typhi. It istherefore expected that herbal drug such as Cantella asiatica can be used as an alternativemedicine to prevent and cure salmonellosis in both animals and human.Experimental laboratory studies were conducted using Completely FactorialRandomized Design. Mice were divided into 4 groups and they were treated respectively withdestilated water (negative control), 125, 250, and 500 mg/kg bw of Centella asiatica extract.The treatment was conducted daily for 2 weeks and the mice were then inoculated with 105cells of S. typhi. The level of IL-6 response were examined 24 hours, 2 weeks, and 4 weeksafter inoculation with S. typhi.The result showed that treatment of mice with Centella asiatica extract significantly(p&lt;0,05) enhaced IL-6 level of Balb/c mice following inoculation with S. typhi. The highes tIL-6 level were observed in mice treated Centella asiatica extract at the dose of 500 mg/kgBW (385,9257±125,4314 pg/ml serum). And the highest IL-6 level were observed at 2 weeksfollowing inoculation with S. typhi (533.4262 ± 81.7184 pg / ml).A further study is recomended to examine the celluler immune response and moredetailed study on the humoral immune response of animals or human before this herbal isused as alternatif medicine to prevent and cure typhoid fever. It is also important to study thebest preparation, the half life, and the side effect of Centella asiatica in human and animals.