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December 2021 – Vol. 104 No. 4


First Detection of Naturally Introgressed BT Cry1Ab in Asian Corn Borer [Ostrinia furnacalis (Guenée)]-Resistant Traditional Maize (Silangan) in the Philippines
Merdelyn T. Caasi-Lit, Eureka Teresa M. Ocampo, Artemio M. Salazar, Jefferson F. Paril, Bryan V. Novio, Bernard B. Panabang, and Angelyn Marta D. Marmeto

Received: November 12, 2019/ Revised: October 9, 2021/ Accepted: November 8, 2021

Resistance against insect pests is one of the most promising and highly favored characteristics of an economically important crop. In the Philippines, the Asian corn borer (ACB), Ostrinia furnacalis (Guenée), is the most destructive insect pest of maize. The discovery of Bacillus thuringiensis and the Bt toxin, which led to the development of Bt corn, effectively controlled this pest. In this study, four traditional varieties of maize that showed resistance against ACB were tested for the presence of Bt Cry1Ab protein. Out of these four, a traditional variety from San Carlos City, Pangasinan, which was initially thought to have natural resistance against the pest, tested positive for the presence of the Cry protein. Confirmatory testing for the presence of the transgene was done through PCR, which also confirmed the locations in Pangasinan where introgressed Silangan are present. This is the first report of natural introgression of cry1Ab in a traditional maize variety in the Philippines. Results of this study can be used as basis to profile the existing CGUARD collection of traditional maize for the presence of transgenes, and in future corn germplasm conservation and utilization efforts. These can also be used to suggest improvement on the existing policy on biosafety measures to be implemented in the country.

Climatic Factors Affecting Maize Grain Yield in Different Growing Areas of the Philippines
Lakshman Kumara P.G.A, Tonette P. Laude, Jose E. Hernandez, Pearl B. Sanchez, Moises A. Dorado, Jose Nestor M. Garcia, Gerardo B. Gauna, and Pompe C. Sta. Cruz

Received: August 26, 2021/ Revised: December 10, 2021/ Accepted:December 16, 2021

Seasonal climate variation is one of the main problems faced by Filipino maize farmers, due to varying climatic elements such as solar radiation, rainfall, relative humidity, air temperature. This study determined the seasonal productivity of selected maize varieties in major growing areas in the Philippines; and identified the yield-limiting climatic factors specific to location and growing season. Grain yield, covering two wet and dry seasons (2016-2018) from seven field trials (representing 3 climatic types) of National Corn Testing (NCT) were used in the study. Climatic data (2016-2018) were gathered from PAGASA weather station nearest to the trial site. Significant variation in monthly solar radiation, monthly rainfall, monthly relative humidity and mean temperature (309.1-786.6 MJ m-2, 19.9-667.5 mm, 64.3-91.4%, 18.8-35.80C, respectively) were observed across seven locations. Relative humidity significantly varied by season. Mean temperatures below 300C and mean relative humidity of more than 80% were observed across locations. Grain yield variations due to season (3394.8-9985.1 kg ha-1), location (1382.4-11931.4 kg ha-1) and climate type (3052.1-8650.9 kg ha-1) were highly significant. Grain yield was significantly affected by cumulative solar radiation specific to variety and season. Solar radiation use efficiency (SRUE) during wet season was highly variable and consistently higher SRUE was observed during dry season. Grain yield of the three varieties were correlated with growing degree days (GDD) during wet and dry seasons (r = 0.28, 0.29, and 0.33). The grain yield of 30B80 was more affected by cumulative solar radiation (r = 0.46), while USM Var10 (r = 0.33) was more associated with GDD. Solar radiation and minimum temperature positively affected the grain yield of variety 30B80, while maximum temperature and relative humidity had negative affect. Solar radiation was the major yield-limiting factor for variety 30B80, while maximum temperature and solar radiation increased grain yield of IPB Var11. The major yield-limiting factor for IPB Var11 was relative humidity. Grain yield of USM Var10 increased with solar radiation, while relative humidity and maximum temperature had negative affect. Location was the maize yield-limiting factor, while relative humidity affected the grain yield of USM Var10 dominantly. Significant seasonal climate variation can be observed in major maize growing areas resulting in different seasonal productivity, while solar radiation and relative humidity are the major yield-limiting climatic factors. Moreover, the hybrid variety, 30B80, can be recommended for dry season in Batac, Tupi and Baybay; wet season in Ubay; and both wet and dry season in Maramag, Kabacan and Ilagan as a high-yielding maize variety.

Establishment of the In Vitro Culture and Plant Regeneration of Anubias barteri var. nana ‘Mini’
Kuan-Hung Lin, Chih-Peng Kuo, and Li-Ru Chen

Received: July 30, 2020/ Revised: November 18, 2021/ Accepted: November 21, 2021

Anubias barteri is an ornamental aquatic plant of economic importance worldwide. Effective removal of contaminants has been a major problem for the in vitro propagation of A. barteri. Hydrogen peroxide (H2O2) was applied as a pre-disinfectant to treat rhizome bud explants of A. barteri var. nana ‘Mini’ followed by disinfection with mercuric chloride (HgCl2) to eliminate in vitro contamination. However, application of 0.1% HgCl2 for 5 min without pre-disinfecting with H2O2 significantly reduced the contamination rate to 44.4% compared to other combinations. Moreover, in vitro shoots of A. barteri var. nana ‘Mini’ were used as plant materials for determining the basal requirement of inorganic minerals. Optimal plant growth was achieved on 1/2 Murashige and Skoog (MS) basal medium. Rhizome bud explants were cultured on 1/2 MS basal medium supplemented with 6-benzyaminopurine (BAP) or thidiazuron (TDZ) in combination with α-napthaleneacetic acid (NAA) to screen for the optimal combinations for shoot proliferation. BAP or TDZ alone at 1 mg L-1, and the combination of 0.5 mg L-1 TDZ and 1 mg L-1 NAA showed significantly higher shoot proliferation rate ranged from 2.4 to 2.7-fold after being cultured for 5 weeks. Ex vitro plantlets after acclimatization adapted well in aquarium. Successful plant regeneration of A. barteri var. nana ‘Mini’ was established through direct shoot organogenesis from rhizome buds and could be used for mass propagation.

Serine/Threonine Protein Phosphatase 1-α (STPP1-α) from Black Tiger Shrimp, Penaeus monodon, an Immune-Related Gene
Jacqueline Marjorie R. Pereda, Neil Andrew D. Bascos, and Mudjekeewis D. Santos

Received: June 14, 2021/ Revised: October 2, 2021/ Accepted: November 17, 2021

Reversible protein phosphorylation is a significant regulatory mechanism in many cellular functions, such as the dephosphorylation of Serine/Threonine protein residues catalyzed by protein phosphatase. In this study, the full-length STPP1-α gene from Penaeus monodon was cloned, characterized, and analyzed for its constitutive expression in WSSV-negative P. monodon organs. The gene was originally an isotig isolated from the gills of P. monodon that survived WSSV infection. PmSTPP1-α gene (GenBank: KX385833) has a total of 2,171 bp, with a 990 open reading frame (ORF) that encodes 329 amino acids (aa), sharing a 93% sequence identity with human Serine/Threonine PP1-α catalytic subunit. The protein has a single conserved catalytic domain and shares almost all the conserved sites and functional residues of the human protein phosphatase, which particularly might have putative functions to viral protein synthesis. Using clustering analysis, PmSTPP1-α was verified to be the –α isoform while the reported L. vannamei STPP1 is the β form. In silico homology modelling predicts similar structures for PmSTPP1-α and STPP1 from H. sapiens. Conserved functional domains for metal binding, target protein interaction, and toxin binding sites were identical in sequence and predicted structure. The observed variations in amino acid sequence were outside these conserved domains but should be further studied to determine their potential effects on function. Current molecular docking predictions for PmSTPP1-α against three proteins from known P. monodon pathogens suggest specific functional interactions with the target protein binding domain and the molecular toxin interaction sites. PmSTPP1-α was found to be ubiquitously and highly expressed in organs of WSSVnegative P. monodon, further investigations on the interactions of this protein will help validate its predicted involvement in the P. monodon immune response.

Rearing Silver Therapon Leiopotherapon plumbeus (Teleostei: Terapontidae) Larvae Using Euryhaline Rotifers as Starter Food
Frolan A. Aya, Vicar Stella N. Nillasca, and Luis Maria B. Garcia

Received: January 20, 2021/ Revised: October 11, 2021/ Accepted:November 29, 2021

The silver therapon Leiopotherapon plumbeus is an important but dwindling freshwater food commodity in Philippine freshwater habitats. The influence of feeding regimes on growth performance and survival of first-feeding silver therapon Leiopotherapon plumbeus larvae fed euryhaline rotifers (Brachionus rotundiformis and B. plicatilis) as starter food was examined. Larvae at 2 days post-hatch (DPH) (1.93 ± 0.07 mm; 200 larvae/basin) were initially reared on rotifers for 12 days followed by Artemia nauplii from 14 to 35 DPH as follows: (A) B. rotundiformis from 2-13 DPH; (B) B. rotundiformis from 2-7 DPH and Moina micrura from 8-13 DPH; and (C) B. plicatilis from 2-13 DPH. After 35 days of rearing, mean survival rates were significantly higher in larvae fed B. rotundiformis (69.2%) than those co-fed B. rotundiformis and Moina micrura (34.6%) or B. plicatilis alone (26.3%). Higher ingestion rates were observed for B. rotundiformis-fed larvae (1.6 ± 0.5 to 4.4 ± 0.5 ind/larvae) than larvae fed B. plicatilis (0.0 to 3.2 ± 0.8 ind/larvae) during the critical initial feeding stage. However, larvae fed B. plicatilis (20.75 ± 0.48 mm) were significantly longer than those fed B. rotundiformis alone (15.62 ± 0.40 mm) or co-fed B. rotundiformis and M. micrura (18.57 ± 0.58 mm). The fastest growth was observed in larvae fed B. plicatilis, with length increment (LI) and specific growth rate (SGR) of 18.8 mm and 6.8% d-1, respectively. Eye diameter, head length, snout length and pre-anal length increased but were not affected when larvae were fed two rotifer species. These results demonstrate that feeding euryhaline rotifer B. rotundiformis from 2 to 13 DPH followed by Artemia is a suitable feeding regime for better survival of silver therapon larvae under laboratory rearing conditions.


Epinasty Accompanies Potassium Nitrate-Induced Flower Bud Break in ‘Carabao’ Mango
Ulysses P. Besas and Calixto M. Protacio

Received: August 19, 2020/ Revised: August 26, 2021/ Accepted: September 05, 2021

The hypothesis that potassium nitrate application promotes epinasty in ‘Carabao’ mango through increased ethylene production was investigated. The degree of drooping, apical primordium growth as affected by shoot ethylene and levels after potassium nitrate spraying were monitored. Evidence presented established for the first time in ‘Carabao’ mango that epinasty occurred just before flower emergence, coinciding with visible bud break, and extended up to 18 days, marking floral anthesis. The possible reasons could be the higher levels of ethylene at 0.31% and earlier increase of ethylene in the shoot apex at 4 hours and apical primordium growth. Increased ethylene levels at 0.21% were observed 2 hours from spraying of potassium nitrate, peaking between 4 to 5 hours both in the leaves and shoot apex and eventually declined at 0.11% thereafter while apical primordium growth started three days from potassium nitrate spray which the emerging buds pushes the side of the apex causing partial bending of apical leaves.

Flowering Regulation of Potted Bougainvillea Plants under Five Water Treatments
Kuan-Hung Lin, Jui-Mei Li, Chun-Wei Wu, and Yu-Sen Chang

Received: June 22, 2020/ Revised: November 01, 2021/ Accepted: November 03, 2021

Bougainvillea (Bougainvillea buttiana) is a very popular evergreen landscape plant in tropical and subtropical areas. The objective of this study was to investigate the growth, flowering, and physiological performance of bougainvillea ‘Taipei Red’ cultivar in response to water-stress conditions that can potentially be used to maximize the economic efficiency and benefits in the development and ACC potential of bougainvillea plants grown in controlled environments. Potted plants were subjected to five different levels of soil VWC: 60% (control), 40%, 20%, 1/3 of leaves visually observed to be drooping (equivalent to 18% VWC), and 2/3 of leaves drooping (= 15% VWC). These five irrigation treatments were applied to those commercial potted plants without flowers from the beginning until the first flower buds appeared, after which normal irrigation was resumed until the end of this experiment. As VWC% decreased, shoot growth rate and days to visible first flower buds decreased, whereas leaf abscission, numbers of flower buds and shoots per plant, and ACC content in leaves increased. The 15% VWC irrigation treatment induced the first flower buds to become visible in fewer days and produced more flower buds and shoots and higher ACC content but shoot growth rate and leaf abscission declined, whereas there were no significant differences in bract size and longevity under all %VWC water deficit irrigation treatments and control. Thus, the widely grown flowering potted bougainvillea ‘Taipei Red’ adapts well to an irrigation schedule of 15% VWC, which can be considered an effective tool for regulating cultivation practices.

Characterization of Dirt on White-Shelled Table Eggs through Image Analysis
Maria Patricia V. Azanza, Dominic C. Panaligan, and Bryan Kenneth V. Desierdo

Received: April 07, 2021/ Revised: September 20, 2021/ Accepted: September 21, 2021

The study reports the laboratory-scale use of image analysis to categorize dirty white-shelled table eggs. Data generated from image analysis were subjected to statistical analysis and compared with established standards categorizing dirty white-shelled table eggs for washing and sanitation or for use in food processing. The average Quartile 1 (2.49%) and Quartile 3 (9.28%) values of percent surface dirt were found to be proximate to quality standard guidelines values of ≤ 3.12% and < 10% from USDA (2000) and PNS (2005), respectively. These limits were recommended as possible guidelines for classifying eggs into those that are acceptable as table eggs, acceptable for processing with washing and sanitation, and unacceptable for food use.

Postharvest 24-Epibrassinolide and Chitosan Treatments Affect Quality of ‘Balady Banzahir’ Limes during Shelf Life
Mohamed A. Awad and Adel D. Al-Qurashi

Received: May 28, 2021/ Revised: October 29, 2021/ Accepted: November 03, 2021

Limes undergo internal metabolic changes during storage at ambient, resulting in rind disorders and green color fading that decrease consumer preferences and market demand. To elucidate the effects of exogenous 24-epibrassinolide (EBR) and chitosan (CT) treatments on the postharvest quality of citrus fruit, freshly harvested mature-green ‘Balady Banzahir’ limes were dipped for 15 min in 20 μM EBR and 1% CT alone or in combination and kept at ambient (23 ± 1°C and 60–70% RH) for 20 days. EBR or CT treatments retained fruit quality during shelf life as shown by higher green peel color (lower a* values), higher titratable acidity (TA) and lower weight loss, total soluble solids (TSS) and TSS/TA ratio compared to that of untreated control. Vitamin C content increased for 8 days in all treatments followed by a gradual decrease thereafter. Total flavonoid content (TFC) in peel increased reaching a peak on the 16ᵗʰ day followed by a sharp decrease thereafter while, in pulp, it decreased with fluctuations. EBR or CT treatments retained higher vitamin C, and TFC contents in both peel and pulp. Antioxidant activity increased with fluctuations in both peel and pulp and was higher in treated fruit than the control. EBR or CT treatments showed higher peroxidase (POD) and lower PPO activities during shelf life than the control. Overall, postharvest dipping in 20 μM EBR or 1% CT could be an effective treatment to retain quality of ‘Balady Banzahir’ limes during 16 days of shelf life.

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