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Abstract Detail

Conservation Biology

Knerr, Anne [1], Tripepi, Robert [2].

Micropropagation of threatened Idaho native Mirabilis macfarlanei.

Mirabilis macfarlanei, Macfarlane's Four-O'Clock, is an attractive perennial herb. M. macfarlanei was classified as threatened in 1996 and appears restricted to portions of Idaho County. Restoration efforts, including seed propagation and transplantation, are ongoing. Micropropagation, growing plant parts in aseptic culture, may hasten recovery. The stages of axillary shoot micropropagation are; I: establishment of surface sterilized tissue and stabilization of initiated microshoots, II: shoot multiplication, III: root formation and IV: acclimatization/moving rooted plantlets into greenhouse conditions. Preliminary data for stage I, II and III are reported herein. In 2020, Mirabilis stems were obtained from the Idaho Botanical Garden and botanist Ann DeBolt. Foliage was removed, stems washed and divided into single node segments. Stem explants were surface sterilized and placed on plant growth media previously shown to support woody plants. Axillary buds broke on all media, but responses varied by genotype. Stabilization of microshoots was challenging, an atypical two week transfer schedule was need to alleviate shoot dieback, which was widespread. Basal Murashige and Skoog (MS) had the highest percent bud break, but more shoots subsequently died compared to other media. Previously published media for micropropagation of Mirabilis jalapa (SR1 and SR2) resulted in primarily callus growth after initial bud break and so were discarded.   Shoots on 1) basal Driver & Kuniyuk (DKW) with 4 µM zeatin; 2) 1/2 MS with 1.1 µM 6-benzylaminopurine (BA), 0.5 µM indole-3-butyric acid (OI); or 3) Preece hybrid media with 4 µM BA (PH) continued to proliferate, indicating the ratio/type of cytokinin, rather than medium salts, was critical for this species. After 4 months of culture, shoots were stabilized and sufficient numbers obtained to begin stage II experiments. Two experiments comparing shoot formation on MS, DKW and PH media for two of the three genotypes were completed. All genotypes produced the most shoots when 4 µM BA was used with either MS or PH media, but differences between treatments were statistically significant for only one of the genotypes tested (MIMA 2).   During stage I and II experiments, a few shoots rooted when cytokinins were absent, but the majority of rooted plants subsequently died.   Adventitious roots from callus were observed on explants on SR2 establishment media, which were more stable, possibly due to the presence of kinetin in the media. Trials comparing rooting on MS media with kinetin and various auxins are ongoing but we have successfully outplanted rooted micropropagated Mirabilis macfarlanei to the greenhouse.

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1 - University of Idaho, University of Idaho Plant Science Department, 875 Perimeter Dr, MS 2333, Moscow, Idaho, 83844-2333, USA
2 - University of Idaho, University of Idaho Plant Science Department, 875 Perimeter Dr, MS 2333, Moscow, Idaho, 83844-2333, United States

Native Plants
Mirabilis macfarlanei.

Presentation Type: Poster
Session: P1, Conservation Biology Posters
Location: Virtual/Virtual
Date: Monday, July 19th, 2021
Time: 5:00 PM(EDT)
Number: P1CB007
Abstract ID:479
Candidate for Awards:None

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