Morels (Morchella spp.) are prized edible and medicinal mushrooms, which are highly welcomed by consumers all over the world for their tasty flavor, rich nutrition and putative health care efficacy. Traditionally, morel production was dependent on their collection from wild environments. However, yields of wild morels are unstable and limited due to climate change, environmental disruption and a diminishing wild-morel resource. As a result, there has always been a profound shortfall in the morel mushroom market. Although a difficult problem to resolve, the domestication and artificial cultivation of morels has attracted immense interest. Research studies and technical developments focusing on these objectives have been underway for more than a century.
Recorded efforts to artificially cultivate morels were initiated by Roze as early as 1887 (Pilz et al. 2007). However, the development of modern techniques for artificial cultivation of morels commenced in 1982 when Ronald Ower, Gary Mills and Jim Malachowski reported the successful fruiting of indoor-cultivated morels. The methods used focused on techniques and nutrient regimes to grow and prepare sclerotia for controlled germination into sporocarps. This technique enabled the artificial cultivation of a M. esculenta strain (later considered to be M. rufobrunnea by Kuo, in 2006) derived from the campus of San Francisco State University. Benefited from this cultivation technique (Pilz et al. 2007). Three patents were issued for the cultivation of morels (US Patents 4594809, 4757640 and 4866878) during 1986-1989 (Ower et al. 1989). However, although many research institutes and individuals have since tried to artificially cultivate morels using the technique developed by Oweret al. , fruiting has been difficult to reproduce (Pilz et al. 2007).
Later efforts to artificially cultivate morels were launched in 2004-2005, while Stewart Miller developed a new technique (US patent 6907691B2) by constructing ectomycorrhizal symbiosis between Morchella mycelium and tree seedlings (Miller 2005). Using this technique, the Diversified Natural Products (DNP) Company associated with Michigan State University achieved successful fruiting of M. rufobrunnea, a red-brown morel, by infecting the root system of Chiquita bean plant seedlings with the myceliumof M. rufobrunnea. The strictly protected technique was used for morel cultivation in the mushroom farming bases set up by the DNP Company in Scottville, Michigan.
In 2010, Sequla Masaphy in Israel reported a successful M. rufobrunnea fruiting body initiation and development in laboratory-scale experiments (Masaphy 2010). The experiments used a planting matrix with grains as a lower layer and potting soil as upper layer. M. rufobrunnea sclerotia were inoculated into the sterile upper layer, and watering treatment was used to induce the sclerotia-developing to fruiting bodies. This laboratory-scale technique made indoor-cultivation of morel possible, but has not been transferred to scale-up industrial morel farming.
Although the low reproducibility and high cost of previously developed morel cultivation techniques restricted large scale cultivation and hardly met market demand, these experiences promoted research on techniques for the artificial cultivation of morel, and inspired Chinese researchers with thoughts and ideas. In Yunnan province, a mycorrhizal symbiotic method is used to artificially cultivate M. conica, with forest wood such as roundleaf poplars (Populus rotundifolia Griff) of 10-20 years age as the symbiotic host (Cheng et al. 2009). While the highest yield using this method was reported to be 492 kg per acre, the shortcomings of this method are obvious. The prevailing conditions for morel cultivation are easily affected by climatic and geographic factors at different sites, thereby reducing the choice of suitable cultivation sites. Furthermore, many broadleaf tree resources such as roundleaf poplars are consumed during the cultivation process, leading to concerns about alterations in forest biodiversity and other negative ecological effects. In addition, the observable uncertainty and instability of morel fruiting associated with this method is restraining its commercial promotion. In Sichuan Province, Zhu Douxi of the Mianyang Mushroom Research Institute announced the successful fruiting of artificially cultivated M. esculenta. However, the related techniques were considered to be limited in reproducibility and yield (Zhao et al. 2009), and leaving some distance to practical morel production.
After over a decade’s research, a research team at the Soil and Fertilizer Institute (SFI) of the Sichuan Academy of Agricultural Sciences (SAAS) invented a novel cultivation technique for morels based on their saprophytic ability. Three amplification steps are used to prepare the seed culture. The seed culture is sown on the farm and covered with soil. Sheds are built above the sown culture to control sunlight, moisture and temperature conditions. In Sichuan Province, the cultivation season for morels lasts from sowing between October and December to fruiting between March and May of the following year. Since the cultivation season is in a relatively quiet period for other farming activities, it avoids time and space competition with other crops. The materials used for morel cultivation are ecological friendly and of low cost, and the operations involved are simple to learn, making the technique widely acceptable and easily popularized.
The area in Sichuan under morel cultivation has expanded rapidly, from less than 16.5 acres in 2012 to over 820 acres in 2015. It is expected to reach over 2470 acres in 2016. The first morel variety which obtained commercialized cultivation approval in China, the “Sichuan Morel No.1” (M. importuna, strain SCYDJ1-A1) was domesticated and bred by the research team in 2014. Another two varieties, the “Sichuan Morel No.3” and “Sichuan Morel No.4”, passed field technique certification in 2015. These varieties all belong to the first batch of domesticated ladder-ridged morels (M. importuna M. Kuo, O’Donnell & T. J. Volk) in China. The “Sichuan Morel No.1” has been commercially cultivated over large areas with stable yields for three consecutive years (2013-2015) (Figure 1). Among the demonstration areas for the cultivation of this morel, a yield of 2050 kg per acre was obtained in 2014 in a cultivation field located beneath orange trees. The highest yield record was in Ganzi zone of Sichuan Province in 2015, which reached 3080 kg per acre (Peng 2015). A new artificially cultivable variety ofM. sextelata M. Kuo has also been domesticated, bred and commercially developed by the same research team (Figure 2). The cultivation area for this morel variety has reached 165 acres.
Figure 1 Commercial cultivation of “Sichuan Morel No.1
The highly efficient method of morel cultivation in Sichuan is a mature technology that generates a stable fruiting yield. Within the entire Sichuan zone, diverse cultivation patterns together with related techniques and germplasm have been widely promoted. Diverse cultivation patterns have spread into various terrains including plain-hills zones, plateau zones, mountain zones, as well as utilizable space beneath fruit and horticultural plants such as orange and osmanthus flower trees. Profits reached 364,000 RMB (over 57100 US dollars) per acre (Peng 2015), which is making the artificial cultivation of morels highly interesting to local farmers and is receiving the enthusiastic support of governmental organizations and policies.
A “Guidance on the Distinctness, Uniformity and Stability (DUS) Test for new plant varieties: ladder-ridged morel” was drafted by the research team at the SFI of SAAS and has passed the reviewing and approval of the Department of Agriculture of China in June 2015. This means that the artificially cultivated ladder-ridged morel “Sichuan Morel No.1” is very possibly going to be included in the tenth batch of the “protection index of the new agricultural plant varieties” in China, which will give the “Sichuan Morel No.1” strengthened variety protection.
As the institution which conserved the largest amount of cultivated M. importuna and M. sextelata germplasmic resources, Sichuan Academy of Agricultural Sciences now has the core techniques for morel seed culture production and other supporting technologies. Systematic evaluation of morel germplasm resources was carried out for the study of the genetics and breeding of morels. Meanwhile, the whole genomes of the artificially cultivated M. importuna SCYDJ1-A1 and M. sextelata varieties have been sequenced and are being analyzed. The study of the M. importuna SCYDJ1-A1 genome has gained international cooperation from the Joint Genome Institute, Department of Energy, USA, and the Laboratory of Excellence ARBRE, Nancy Center, Institut National de la Recherche Agronomique (INRA), France, within the framework of the 1000 Fungal Genomes (1KFG) project. The genomic data of M. importuna SCYDJ1-A1 has been recently released in the IMG genomic database. Genomic studies of artificially cultivated morels will attempt to elucidate the molecular mechanisms associated with the fruiting of morel under artificial cultivation conditions, aiming for possible domestication and artificial cultivation of a wider range of morel species.
We hope the successful domestication and cultivation of M. importuna SCYDJ1-A1 and M. sextelata in Sichuan, from laboratory research to industrialized cultivation and commercial promotion, will contribute to ecological-friendly solutions and the realization of a global green-agricultural revolution.
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Masaphy S (2010) Biotechnology of morel mushrooms: successful fruiting body formation and development in a soilless system. Biotechnol Lett 32:1523-1527. doi:10.1007/s10529-010-0328-3
Miller SC (2005) Cultivation of Morchella. USA Patent US 6907691 B2
Ower RD, Mills GL, Malachowski JA (1989) Cultivation of Morchella. USA Patent US 4866878
Peng W (2015) The highest yield record of morel was renewed by the new morel variety bred by Sichuan Academy of Agricultural Sciences. Sichuan Agricultural Science and Technology 5:49.
Pilz D, McLain R, Alexander S, Villarreal-Ruiz L, Berch S, Wurtz TL, Parks CG, McFarlane E, Baker B, Molina R, Smith JE (2007) Ecology and management of morels harvested from the forests of western north America. Forest Service, Pacific Northwest Research Station, United States Department of Agriculture. General Technical Report, PNW-GTR-710
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Figure 1 Artificially cultivated ladder-ridged morel variety “Sichuan Morel No.1” (M. importuna SCYDJ1-A1). A close view of a fruiting body and an overlook of the farm plots being fruiting.
Figure 2 Artificially cultivated variety of M. sextelata. A close view of the fruiting bodies and an overlook of the farm plots being fruiting.