Rinaldi Sjahril

High-efficiency Agrobacterium-mediated transformation of Phalaenopsis using meropenem, a novel antibiotic to eliminate Agrobacterium

Summary The type and concentration of antibiotic used to eliminate Agrobacterium affected the efficiency of bacterial elimination from, and phytotoxicity to Phalaenopsis cells. To eliminate Agrobacterium, high concentrations (500 mg l–1) of cefotaxime and carbenicillin were required, which also caused necrosis of cells when added to the culture medium for 2 weeks. In contrast, meropenem successfully suppressed growth of the bacteria at low concentrations (5 mg l–1) and had no phytotoxic effect. A reproducible genetic transformation method for Phalaenopsis was established by co-cultivating cell suspension cultures of Phalaenopsis Wataboushi ‘#6.13’ with A. tumefaciens strain ‘EHA101’ (pIG121Hm), harbouring genes for -glucuronidase (GUS) and hygromycin resistance (hpt). The highest transformation efficiency was obtained when 5 d-old cells were infected for 2 h after sub-culture with Agrobacterium, as assessed by transient as well as stable GUS expression. Successful GUS gene expression in putative transgenic plantlets was confirmed by histochemical GUS assays on calli, protocorm-like bodies (PLBs), leaves and roots of plantlets selected on New Dogashima medium (NDM) containing 25 mg l–1 hygromycin. PCR and Southern blot analysis of genomic DNA confirmed successful incorporation and transformation of the GUS gene in regenerated plantlets. Agrobacterium was completely eliminated using 10 mg l–1 meropenem during a 10 min wash after 3 d co-cultivation followed by 5 mg l–1 for the first 3 months of culture in Gelrite-solidified medium. Ninety-two percent of transgenic PLBs obtained after 6 months, and 97% of transgenic plantlets after 12 months showed almost complete elimination of Agrobacterium.

Harvest index and yield components of aerobic rice (Oryza sativa) under effect of water, varieties and seed priming

This research was conducted to investigate harvest index and yield components of aerobic rice (Oryza sativa) under effect of water, varieties and seed priming in the tropical region. The experiment was set in split-split plot design. The treatments were priming seed with poly ethylene glycol (PEG), treated (P1) and untreated (P0) as sub-sub-plot, Three aerobic rice cultivars as sub-plot consisted of Inpago 8, new potential one (V1), IR64, susceptible aerobic rice cultivar (V2) and Situbagendit, a normal aerobic rice cultivar (V3) as sub-plot, three irrigation intervals namely irrigated every 5 days (W1), irrigated every 10 days (W2) and irrigated every 15 days (W3) set as main plot. Yield components and harvest index parameters were calculated. Results indicated significant and insignificant difference, in spite these, there was no significant difference the date of W1 and primed seed revealed the highest data compared with W2, W3 and non-primed seed. High harvest index revealed by W1V1P0 was 0.827 and the smallest by W1V3P1. Grain yield ranging between 4.49-1.60 ton ha-1 and straw about 15.39-5.33 ton ha-1 depend upon aerobic rice cultivars and water availability. More research about aerobic rice technology need to face water problem in the future.