Reliable normalization and accurate quantification are essential for gene expression studies in oil palm mesocarp. This study assessed three candidate reference genes (Actin, GAPDH, and EF1α) for stability using four algorithms (ΔCt, BestKeeper, NormFinder, and GeNorm). Actin was consistently identified as the most stable single housekeeping gene (HKG) (stability value 0.021), while the combination of GAPDH and EF1α provided the most stable normalization pair (stability value 0.017), supporting their use as internal controls for normalization. Normalized expression analysis of two key biosynthetic genes, acetyl-CoA carboxylase (ACCase) and phytoene synthase (Psy), was conducted in contrasting phenotypes differing in oil yield and carotene content. The high-yielding, high-carotene genotype displayed lower ΔCt values for both ACCase (4.67 vs. 6.19) and Psy (4.75 vs. 5.26), corresponding to 2.86-fold and 1.42-fold higher expression, respectively. These expression differences aligned closely with phenotypic outcomes, as the superior traits achieved a 40.8% increase in oil yield and a 155.3% increase in carotene content. Expression patterns showed stage-specific specialization: ACCase was upregulated during the unripe stage, enhancing fatty acid biosynthesis, while Psy was most differentially expressed during ripening, coinciding with carotenoid accumulation. Together, these findings suggest that transcript abundance of oil and carotenoid pathways may be coordinated in elite oil palm and provide a framework for linking gene expression with metabolic output, which may inform future efforts to improve oil yield and quality

The rising global demand for palm oil necessitates innovative strategies to accelerate yield improvement and ensure sustainable production. Conventional propagation methods are limited by long regeneration cycles, making tissue culture a more practical alternative that relies on elite ortet identification. This preliminary study aimed to evaluate crude palm oil quality, leaf metabolite profiles, and gene expression as early indicators for selecting elite ortets. Mature fruits were used to assess oil yield, free fatty acid, and β-carotene contents, while leaves were analyzed for chlorophyll and total phenolic content. Based on biochemical screening, three candidate ortets were further evaluated for the expression of acetyl-CoA carboxylase (ACCase) and phytoene synthase (PSY) genes. Oil yield ranged from 77-83%, FFA 5-9%, and β-carotene 200-450 mg kg-1 CPO across candidates. Candidate 3.7 exhibited the highest oil yield and elevated ACCase expression, while candidate 6.12 showed the highest β-carotene content and PSY expression. Candidate 5.7 demonstrated relatively low FFA and favorable chlorophyll levels. These results suggest an association between ACCase expression and oil yield, as well as between PSY expression and β- carotene accumulation. Collectively, these findings support a proof-of-concept for an integrated profiling strategy to select elite ortets for advanced tissue culture propagation.

Kopyor coconut is a type of Indonesian coconut with a unique flavor and texture, which makes it attractive to consumers. Kopyor coconut is commonly consumed as a fresh fruit and has a short shelf life. Therefore, innovation in kopyor coconut product development is needed to extend its shelf life; one potential method is pasteurization. This study aims to extend the shelf life of kopyor coconut by determining the optimum thermal pasteurization process for kopyor coconut flesh products and evaluating the impact on product quality during storage at room temperature. Thermal adequacy assessment includes two test steps: the appliance’s thermal distribution test and the product’s thermal penetration test conducted at boiling water temperature (98°C). Kopyor coconut was formulated with citric acid as an acidity regulator and sugar as a sweetener and then packaged in boil-pack plastic packaging. Product characteristics observed included pH value, free fatty acid (FFA), total soluble solids (°Brix), and microbial contamination. Based on the thermal adequacy test results, the minimum time for the pasteurization process of kopyor coconut products is 17 min. The kopyor coconut products exhibited satisfying quality as no microbes were detected from the TPC analysis, which means no microbial growth during storage. The pH value during eight weeks of storage was 3.68-3.91 and is still within the requirements of acidified foods. The FFA content was 1.59-2.27%, while the total soluble solids were constant at 19 °Brix. In conclusion, pasteurization treatment maintained the product quality of kopyor coconut flesh during eight weeks of storage at room temperature.

In vitro embryo cultivation is the principal method for reproducing the kopyor coconut, an indigenous Indonesian species. Acclimatization is a critical step in this approach. The purpose of this study was to improve the survival and development rate of kopyor coconut seedlings grown in vitro during the acclimatization phase by using biological, organic, and mixed organic-biological biostimulants. This study employed a completely randomized block design that comprised the inclusion of biological, organic, and mixed biological-organic biostimulants, with no biostimulant as a control. The biological stimulant employed in this study was arbuscular mycorrhizal fungus (AMF), while the organic biostimulant was seaweed extract. Each treatment had 50 plantlets in triplicate. The results demonstrated that the treatment of biological and organic biostimulants increased plantlet survival rates during acclimatization, beginning 2 months after application and remaining consistent for 4 months. The biological stimulant application produced the highest plantlet survival rate (>94%). Based on how quickly the plantlets transitioned to the next stage, it was discovered that after 2-months incubation, most of the plantlets had already transferred to the second phase of acclimatization (opened tunnel). After 4-months incubation, the biological stimulant treatment produced the most plantlets at the later stage. However, throughout the 4-month acclimation period, more plantlets were transported from the pre-nursery to the main nursery, particularly with the use of organic biostimulants (56-64%). Keywords: arbuscular mycorrhizal fungi, plantlet, survival rate, seaweed

Kopyor coconut (Cocos nucifera var. Kopyor), a native Indonesian coconut, differs from common coconuts because it has brittle flesh (endosperm) due to a natural genetic mutation. Kopyor coconut seedlings have been successfully cultivated from the tissue culture technique, which can produce kopyor above 99%. Nowadays, the demand for kopyor continues to increase. The cultivation of kopyor is centralized in several locations in Indonesia. Hence, the time of kopyor distribution to consumers is crucial in the kopyor business. This study evaluated changes in the characteristics of whole fruit and peeled kopyor coconuts during distribution. The observations included quality attributes (appearance, aroma, texture, and taste), physical observations (pH and water content), and microbial observations using the total plate count method. Whole kopyor showed better quality attributes than peeled kopyor. Peeled kopyor coconut flesh began to change color to yellowish-white, mushy, and had a rancid smell and a sour taste in the second week, while whole fruit kopyor in the fourth week. In conclusion, the distribution of peeled kopyor should be carried out in less than two weeks, or even sooner, while whole fruit kopyor can be distributed for up to two weeks without altering the characteristic taste of kopyor.

The oil palm (Elaeis guineensis Jacq.) is the primary source of vegetable oil cultivation globally, and it is considered to be the most profitable oil commodity per hectare. E. guineensis Jacq. micropropagation technique can be achieved through the somatic embryogenesis process, allowing the efficient and true-to-type propagation of plants. The somatic embryogenesis (SE) mechanism describes the interaction of endogenous signals and gene reprogramming, generating signaling that develops embryo pathways. Somatic embryogenesis receptor-like kinases (SERKs) are leucine-rich repeat receptor-like kinases expressed in numerous plant signaling pathways. The SERK gene contributes an essential part in the development of embryos from single somatic cells. The characterization of SERK genes in E. guineensis Jacq. is still limited and under-explored. The objective of this research is to examine the characteristics of SERK gene by comparing the differences and similarities of SERK gene in E. guineensis Jacq. to other crops as well as their evolutionary relationship. The method was initiated by identifying nucleotide sequences from the National Center for Biotechnology Information (NCBI) database. Furthermore, it consists of the analysis of nucleotide alignment, alignment of amino acid sequences, protein analysis, protein motif function discovery and analysis of phylogenetic tree. The phylogenetic tree shows E. guineensis Jacq. has a very close relationship with Dendrobium officinale based on the SERK protein and protein motifs. These insights have implications for unraveling the long-term embryo differentiation processes of E. guineensis Jacq. and other crops during propagation by somatic embryogenesis.

Kopyor coconut is a unique coconut native to Indonesia characterized by crumbly flesh and a savory taste. Unlike common coconuts, kopyor coconut undergoes natural mutation, lacking the ability to produce the enzyme α-galactosidase, which results in its distinctive flesh compared to normal coconuts. In nature, kopyor coconuts are rarely found, making them expensive. Kopyor coconuts are distributed as whole fruits, peeled fruits, or repackaged flesh. Kopyor coconut has a shorter shelf life than normal coconut, therefore efforts to extend the shelf life of kopyor coconut flesh are necessary. This study investigated the efficacy of blanching and food additives (potassium sorbate and sugar) in extending the shelf life of kopyor coconut flesh stored under chiller conditions in aluminum pouches. The results showed that the appearance of all treatments remained acceptable until the 6th week. The TSC (Total solid content) results indicated that the blanching-sugar treatment had the lowest values among all treatments. The pH of each treatment did not differ significantly, except for the sugar without blanching treatment, where the pH tended to be lower than other treatments and the control. Based on TPC (Total plate count) result, blanching treatment effectively inhibited microbial growth in kopyor coconut flesh until the 6th week, especially in treatments without food additives. Organoleptic tests on appearance, aroma, taste, and texture showed the highest overall preference for the blanching-sugar treatment.

The utilization of temporary immersion system-bioreactors (TIB) has shown promise for sugarcane micropropagation due to its capacity for high-yield seedlings production. However, the temporary immersion system also carries the risk of somaclonal variations (SV) in regenerated plants. SV, encompassing phenotypic changes resulting from genetic or epigenetic alterations, and it presents challenges in preserving the genetic uniformity of the seedlings, a crucial factor for sugarcane productivity. A molecular marker like Simple Sequence Repeats (SSR) offers a reliable means to assess the genetic stability of TIB-derived sugarcane seedlings, ensurinng that the temporary immersion system-based micropropagation produces true-to-type planting materials. In this study, SSR analysis was conducted to determine the relative genetic stability of TIB-derived sugarcanes, using 15 SSR markers, generating over 200 DNA fragments ranging from 150 to 4,000 bp in size. The genetic stability was calculated as the Jaccard’s similarity index of the SSR patterns of TIB-derived sugarcanes compared to their mother plants. The genetic stability varied between 92 and 96% in three Indonesian sugarcane varieties (PSKA 942, PS 094, and PS 091) which is relatively high considering the high cell mass multiplication in TIB (up to 30 multiplies). Morphological observations in the field also revealed no differences between TIB-derived sugarcane and their mother plants, convincing the true-to-type of micropropagation products. This study demonstrated the high relative genetic stability of TIB-derived sugarcanes, paving the way for large-scale commercial application in plantations.

Indonesia has released some elite varieties of sugarcane that are suitable for Indonesian climatic and land conditions. Therefore, large quantities of these elite sugarcane seedlings are needed to support the Indonesia's sugar self-sufficiency programs. The large quantities seedlings can be provided through scaling-up in vitro propagation method using bioreactors, such as Temporary Immersion Bioreactor (TIB). Here, we conducted a study to analyze the response of different plant genetic materials on the in vitro propagation of some Indonesian elite sugarcane varieties using TIB. The sugarcane varieties used for the study were the rainfed sugarcane varieties (PSKA 942, PS 094) and the irrigated sugarcane varieties (PS 091, PS 881), released by the Indonesian Sugar Research Institute. The plant materials used as explants for in vitro propagation were the young spindle leaves isolated from the plant canes. The in vitro propagation stages were explants preparation and sterilization, callus initiation, callus proliferation and regeneration in TIB, shoot maturation, and acclimatization. Results showed that all sugarcane varieties have been successfully induced to form callus ranged 11.6 – 33.5%, proliferate and regenerate in TIB. Proliferation rates in TIB ranged 4.45 – 33.76 multiplies of biomass after two proliferation cycles. However, in general, the rainfed sugarcane varieties showed better response, growth, and regeneration rate than the irrigated sugarcane varieties. The in vitro-derived sugarcane seedlings have been successfully obtained from all varieties except for PS 881, with the highest shoots production was PSKA 942 (147.7 shoots/flask).

Genome editing through cisgenesis develops into scientific breakthroughs in accelerating oil palm breeding programs. However, one remaining problem is the low success of transformed-calli regeneration, while its scientific explanation is still underexplored. This study aimed to characterize and regenerate transformed-calli using various amino acids and antioxidants. Transformed callus that did not regenerate (un-regenerated transformed callus or UTC) after the transformation process was taken, then T-DNA integration was detected using the NPTII gene. Furthermore, the UTC was divided into four types based on morphological characteristics. The four types of UTCs were regenerated on media enriched with glutamine (for Type-1 callus), cysteine and putrescine (for Type-2 callus), and a combination of cysteine and ascorbic acid (for Type-3 and Type-4 callus). The research results obtained NPTII successfully amplified with a band size of 700bp. The results showed that on Type-1 callus, enrichment media with 10 mg L-1 L-glutamine could induce the formation of new nodular structures on UTC Type-1. On Type-2, media enriched with 5 mg L-1 L-cysteine + 20 mg L-1 putrescine increased the density of callus structures. Media enriched with 25 mg L-1 ascorbic acid + 25 mg L-1 L-cysteine could prevent the spread of brown callus on Type-3 callus, while Type-4 callus did not show any response and became dry. Our new findings will facilitate the basic research and unregenerated transformed callus and morphological callus development behavior in oil palm.

Drought poses a significant threat to global food security, particularly impacting crops like oil palm. Selecting genes for genome editing to enhance drought tolerance presents formidable challenges. To ensure that the target gene is chosen correctly and results in the desired character, a pilot study is necessary to determine the target gene for knockout. Two genes drought-related, AtBRL3 and AtOST2, were scrutinized in this context. Aligned with the Elaeis guineensis genome, their neighbouring proteins and gene ontology were analysed to identify potential targets for genome editing. AtBRL3, identified as BRL1 (XP_010913986.1) in E. guineensis, exhibited 58.48% identity and 100% coverage. It interacts with 12 nodes, including BIR1, BRI1, and AT2G20050, crucial for signalling pathways and cellular responses. Molecular function analysis revealed kinase activity. AtOST2 showed high similarity to plasma membrane ATPase/HA1 (XP_010913679.1) in E. guineensis, with 87.46% identity and 100% query cover. It correlated with 14 genes associated with ABA stimulus, stomatal movement, and hormone response. EgBRL1 and EgHA1, resembling AtBRL3 and AtOST2, respectively, emerge as promising targets for developing drought-tolerant oil palm cultivars through gene editing. Nonetheless, further validation through in vitro gRNA target selection and in vivo conversion of OST2/BRL3-containing plasmids in oil palm calluses is indispensable to demonstrate their efficacy in conferring novel drought resistance traits.

Abstract Browning on in vitro culture is one of the problems in somatic embryo regeneration that leads to growth inhibition and death of explants. This study aimed to prevent and control browning of oil palm somatic embryos (SE) in the Temporary Immersion System (TIS). The research was conducted in two stages; the first stage was applying an antioxidant mixture at concentrations of 20, 50, and 100 mg L-1 on the browning palm oil SE in TIS. The second stage was carried out by modification of the basal media, namely DF (control), MS, SM, and SMT. The explants used in experiment 2 were browning and fresh SE. The results showed that using 50 ppm antioxidants mixture increased the formation of new SE by up to 15 embryos per flask. Applying SMT basal media on browning SE could decrease browning rate sharply after two cycle cultures by up to 60% browning rate reduction. In this media, it was also seen that the number of new SE increased by up to 250 embryos and produced 15 germinants, while in control, only 60 SE and five germinants were formed. Whereas using SMT basal medium on fresh embryos could prevent browning and increase the formation of new embryos and germinants. In conclusion, using 50 ppm antioxidants can stimulate the formation of new embryos. Using SMT basal media could prevent browning and overcome the occurrence of browning in embryos by increasing the formation of new embryos and germinants.

Laboratorium kultur jaringan memiliki peran dalam industri perkebunan kelapa sawit, salah satunya yaitu untuk produksi bibit klonal skala massal. Produksi bibit klonal kelapa sawit umumnya dilakukan melalui teknik embriogenesis somatik yang melibatkan beberapa tahap. Seluruh rangkaian proses produksi tak terlepas dari alur pendataan yang memastikan proses berjalan dengan benar dan hasil produk akurat. Penerapan kode QR dalam pendataan di laboratorium kultur jaringan, seperti dalam produksi bibit klonal kelapa sawit, memberikan keuntungan dengan menggantikan pendataan manual yang rentan terhadap kesalahan manusia dan waktu yang tidak efisien. Aplikasi pendataan berbasis kode QR, seperti Tissue Culture Tracking membantu dalam pelabelan digital dan pemantauan proses, yang memungkinkan penelusuran data yang akurat serta meningkatkan efisiensi produksi bibit klonal. Beberapa tantangan dalam penerapan digitalisasi data dalam laboratorium kultur jaringan antara lain akses internet yang memadai, kompatibilitas perangkat, serta keterampilan dan budaya kerja personel. Revitalisasi fasilitas, pelatihan, dan pembiasaan adalah solusi agar digitalisasi pendataan berbasis kode QR dalam laboratorium kultur jaringan dapat diimplementasikan dengan baik.

The Zambli variety of date palm shows potential for cultivation in tropical regions, as its fruits are edible during the Rutab stage. However, large-scale production of Zambli seedlings presents a significant challenge. In vitro propagation offers a solution for producing large quantities of clonal planting material. This study focuses on inducing callus formation from the four-layered shoot tips of young leaves and regenerating these calli into plantlets through somatic embryogenesis. Explants were cultured on a modified MS medium with 10, 50, or 100 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D), combined with 1 or 3 mg L-1 N6-(2-isopentenyl)adenine (2-iP). Embryo maturation was performed on the same medium without 2,4-D, while a hormone-free medium was used for plantlet regeneration. The results indicated that the highest callus induction occurred from the younger leaf layer (layer 1) in the medium containing 100 mg L-1 2,4-D and 1 mg L-1 2-iP, achieving a callus formation rate of 82.3%. Successful callus induction was achieved from the first, second, and third layers of young leaves. Somatic embryo maturation and plantlet regeneration were also completed, producing vigorous, well-rooted plantlets. Additionally, the development of date palm cv. Zambli in vitro culture through somatic embryogenesis was confirmed through histological analysis.

Optimization of in vitro shoot growth is necessary to shorten the culture time and produce vigorous oil palm plantlets. This research was conducted to determine the best media and culture techniques to accelerate in vitro shoot growth of oil palm. Shoots of oil palm derived from somatic embryogenesis were grown on DF media with two culture systems (solid medium and double-layer) combined with hormone treatments (0.5-1 mg L-1 giberellin/GA3 and 0.5 mg L-1 Benzyl amino purine/BAP or thidiazuron/ TDZ). Further optimization was conducted using different bottle closures (polypropylene screw caps and plastic wraps) and macronutrients (standard or double concentrations). This research was conducted using a completely randomized design (CRD), with each treatment consisting of 5 bottle replications and each bottle consisting of 5 shoots. The results showed that media with double-layer system combined with GA3 (0.5-1 mg L-1) and TDZ (0.5 mg L-1) gave the highest shoot height increment. The use of double-strength macronutrient media combined with screw bottle caps increased shoot height (136-167 %) and decreased shoot tip necrosis (0-24 %). Plastic wrap bottle caps increased shoot tip necrosis (STN), while doubling macronutrients reduced STN. The growth of oil palm shoots began to slow down after 5 weeks of culture. In conclusion, the optimal conditions for in vitro shoot growth of oil palm were at usage of double-layer media added with GA3 0.5-1 mg L-1, TDZ 0.5 mg L-1, and double macronutrients on bottle jars with polypropylene screw caps.

Contamination in the in vitro culture is a critical problem causing the failure of seed production. Contamination in the oil palm plantlet is detrimental, considering that oil palm propagation is difficult and takes a long time. This research aimed to study the effect of sterilization during acclimatization of the contaminated oil palm plantlets by fungi on viability and to determine the optimum viability achieved from the contaminated materials. The materials used were contaminated plantlets of oil palm with roots, four leaves, and a height of about 17 cm. The plantlets were removed from the tube and cleaned with running tap water, then were sterilized, with treatments P1: soaking in benomyl-mancozeb-sodium hypochlorite and mannitol and rinsing with aquadest, P2: soaking in benomyl-mancozeb, P3: soaking in mancozeb. Cleaning plantlets under running tap water was carried out as a control treatment. The results showed that at 10 weeks after acclimatization, the survival rate of plantlets in each treatment (P1, P2, and P3) was significantly higher than that of the control. Sterilization methods affect the time new leaves emerge, leaf condition after sterilization treatment, and shoot height. The lowest fungal contamination after treatments was found in P2, followed by P3. After 3 months, plantlet survival rate decreased, with the highest survival rate in treatment P3 (32.3%) followed by treatment P2 (22.5%). In conclusion, acclimatization of contaminated oil palm plantlets can be carried out using a suitable sterilization treatment. Sterilization affects the survival rate and growth of in vitro-contaminated oil palm plantlets during acclimatization.

The performance of kopyor Dwarf coconuts from embryo culture in the field has not been reported. This study was conducted to determine the difference in vegetative and generative performances of three fruit color phenotypes (brown, green, and yellow) of kopyor Dwarf coconuts in the first year after the first flower appeared. The coconuts were planted in Bogor, West Java at 260 masl with average temperature 26.9 ºC and average rainfall 4,300 mm/year. Each color phenotype was represented by 20 kopyor coconut trees from the same planting date that had not been flowering yet. When the first flowers appeared, Kopyor Brown Dwarf (KBD) had 14.6 fronds, while Kopyor Yellow Dwarf (KYD) and Kopyor Green Dwarf (KGD) had 15.5 and 17.1 fronds respectively. Other vegetative components when the first flower appeared were not significantly difference among the three color phenotypes such as stem girth (90.7-99.2 cm), stem height (18.6-23.9 cm), frond length (3.9-4.2 m) and canopy diameter (5.8-6.1 m). KBD coconuts started flowering faster than that of KGD and KYD. The numbers of flowers formed in the first year of flowering were 15 to 17 flowers per tree. There was an initial sharp decrease in the survival of young fruits, but this levelled off after 2-3 months. On average 18-22 fruits per bunch at flowering decreased to 5-6 fruits per bunch at maturity. The survival of fruits in KGD (6.2 fruits per bunch) was higher than KBD (4.0 fruits) and KYD (4.5 fruits) at 11 months after flowering. The average fruit size and weight of brown phenotype were higher than green and yellow phenotypes. The mature brown fruits had a lower husk percentage, but higher shell and fruit meat percentages than those of the green and yellow fruits.[Keywords: fruit color phenotype, kopyor Dwarf coconut, fruit abortion, fruit quality] AbstrakKeragaan kelapa Genjah kopyor asal kultur embrio di lapang belum pernah dilaporkan. Penelitian ini dilakukan untuk mengamati perbedaan keragaan vegetatif dan generatif tiga varietas kelapa Genjah kopyor yang berbeda dari warna buah (coklat, hijau dan kuning) pada tahun pertama sejak bunga pertama muncul. Kelapa tersebut ditanam di Bogor, Jawa Barat pada 260 mdpl dengan rerata suhu 26,9 ºC dan curah hujan 4.300 mm/tahun. Tiap fenotipe warna diwakili oleh 20 pohon kelapa kopyor berumur sama yang belum berbunga. Pada saat bunga pertama muncul, kelapa Genjah Coklat Kopyor (GCK) memiliki 14,6 pelepah daun, sedangkan Genjah Kuning Kopyor (GKK) dan Genjah Hijau Kopyor (GHK) berturut-turut memiliki 15,5 dan 17,1 pelepah. Parameter vegetatif lain ketika bunga pertama muncul tidak berbeda nyata antar fenotipe warna misalnya lingkar batang (90,7-99,2 cm), tinggi batang (18,6-23,9 cm), panjang pelepah (3,9-4,2 m) dan diameter tajuk (5,8-6,1 m). GCK mulai berbunga lebih cepat dibandingkan dengan GHK dan GKK. Jumlah bunga yang terbentuk selama satu tahun pertama pembungaan adalah 15 sampai 17 bunga per pohon. Jumlah buah muda yang bertahan hidup menurun tajam pada awal, namun relatif stabil setelah 2-3 bulan. Rata-rata terbentuk sebanyak 18-22 buah per tandan pada awal pembungaan dan menurun menjadi 5-6 buah per tandan saat dewasa. Buah yang bertahan hidup pada GHK (6,2 buah per tandan) lebih tinggi dibanding GCK (4,0 buah) dan GKK (4,5 buah) pada umur 11 bulan setelah bunga mekar. Rata-rata ukuran dan bobot buah fenotipe coklat lebih tinggi daripada fenotipe hijau dan kuning. Buah kelapa GCK mempunyai persentase sabut yang lebih rendah, tetapi persentase tempurung dan daging buah yang lebih tinggi dibandingkan dengan buah kelapa GHK dan GKK.[Kata kunci: fenotipe warna buah, kelapa Genjah kopyor, kerontokan buah, kualitas buah]

AbstrakBioreaktor perendaman sesaat (BPS) telah digunakan secara luas untuk propagasi skala massal berbagai tanaman penting, termasuk tanaman tebu. BPS menyediakan sistem kultur semi-otomatis dan kondisi optimal bagi pertumbuhan tanaman. Beberapa faktor menentukan pertumbuhan tanaman pada BPS, salah satunya densitas dari eksplan. Oleh karena itu, penelitian dilakukan untuk menentukan bobot awal yang optimal untuk kalus tebu yang dikulturkan pada BPS, serta mengevaluasi pengaruh perbedaan bobot awal kalus tersebut terhadap proliferasi dan regenerasi kalus tebu. Kalus tebu diinduksi dari daun muda yang masih menggulung dari empat varietas tebu unggul Indonesia. Bobot awal kalus yang dikultur ke dalam bejana TIB yaitu 0,05 g; 0,1 g; 0,2 g; 0,5 g; dan 1,0 g untuk setiap bejana. Kalus kemudian melalui tahap proliferasi pada BPS sebanyak tiga siklus, kemudian kalus diregenerasi pada BPS dengan perlakuan auksin dan sitokinin. Hasil penelitian menunjukkan bahwa 0,2 g merupakan bobot awal kalus yang efisien untuk proliferasi kalus tebu pada TIB, dimana eksponensial multiplikasi kalus tercapai pada bobot awal tersebut, yaitu untuk masing-masing varietas 130,3 kali (PSKA 942), 136,8 kali (PS 094), 21,3 (PS 881), dan 12,9 kali (PS 091) setelah 12 minggu. Densitas kalus pada TIB berkorelasi negatif dengan karakteristik fisikokimia medium. Hal ini menggambarkan variasi intensitas pertumbuhan dan metabolisme kalus dengan adanya perbedaan densitas pada BPS. Penggunaan BAP 0,2 mg L-1 bersama kinetin 0,2 mg L-1 paling sesuai untuk memacu regenerasi kalus tebu dengan menghasilkan jumlah tunas terbanyak dalam waktu relatif lebih cepat (1 – 2 minggu lebih cepat) dibandingkan perlakuan lainnya dan dengan tingkat kejadian pencoklatan yang rendah.[Kata kunci: kultur in vitro, kultur cair, proliferasi]AbstractTemporary immersion bioreactor (TIB) has been utilized for the mass-scale propagation of many important plants, including sugarcane. TIB facilitates a semiautomated culture system and provides optimal conditions for plant growth. Several factors determine plant growth in the TIB, such as explant density. Therefore, an experiment was carried out to determine the optimal initial weight of sugarcane calli and to evaluate its effect on the proliferation and regeneration in TIB. Sugarcane calli were induced from spindle leaves isolated from four Indonesian prime sugarcane varieties. The initial weights of the calli cultured in the TIB flasks were 0.05 g, 0.1 g, 0.2 g, 0.5 g and 1.0 g per flask. The calli were proliferated through three cycles in TIB, and subsequently regenerated in TIB with auxin and cytokinin treatments. The results of the experiments showed that 0.2 g was the most efficient initial weight for sugarcane callus proliferation in the TIB, resulting in an exponential multiplication rate of 130.3-fold (PSKA 942), 136.8-fold (PS 094), 21.3-fold (PS 881), and 12.9-fold (PS 091) within 12 weeks. In the TIB, callus density showed a negative correlation with the physicochemical properties of the medium, demonstrating various growth intensities or metabolic activities of calli at different densities in the TIB. The use of 0.2 mg L-1 BAP along with 0.2 mg L-1 kinetin was suitable for promoting the regeneration of sugarcane calli and producing the highest number of shoots in a relatively short amount of time (1 – 2 weeks faster) with low incidences of browning.[Keywords: in vitro culture, liquid culture, proliferation]

Drought is one of the limiting factors in crop cultivation, such as in oil palm (Elaeis guineensis Jacq.). The transgenic approaches are expected to increase plant tolerance to drought stress and minimize low productivity when drought occurs. Proline is an osmoprotectant compound in plants which its biosynthesis involved the P5CS gene. The objective of this study was to evaluate the tolerance level of P5CS-transgenic oil palm to drought stress induced by polyethylene glycol 6000 (PEG-6000). In this present study, the transgenic and non-transgenic oil palms were treated by 0, 2, and 4% PEG-6000 under in vitro conditions. The experiment was arranged as a factorial completely randomized design with three replications. The drought level score, total chlorophyll content, carotenoids, and proline content, as well as P5CS gene expression in leaf tissues were observed at 7 and 14 days after stress treatments. The result showed that transgenic plantlets had a lower drought level score than those of non-transgenic lines. A concentration of 4% PEG-6000 treatment reduced the total chlorophyll and carotenoids contents than that of 2% concentration in non-transgenic plantlets at 7 and 14 day after treatments (DAT). In addition, proline content and P5CS gene expression level in transgenic had been significantly increased during stress treatment. Based on these results, it can be concluded that the P5CS transgene increased the drought stress tolerance of oil palm.