Cryopreservation of Pistacia vera embryonic axes

Abstract

This preliminary study investigated the conservation of Pistacia vera genetic resources using seeds and isolated embryonic axes. First, the effect of storing seeds in ambient conditions on embryo viability was evaluated by in vitro culture. The germination rate of P. vera embryonic axes gradually decreased from 100% to 31% after 30-month storage of seeds. Cryopreservation may thus be necessary for the long-term conservation of embryos. A simple protocol was set up using embryonic axes. It included a single dehydration step with silica gel prior to direct freezing in liquid nitrogen (-196°C). The optimal germination rate was obtained after 60 min dehydration (water content of 0.2 grams of water per gram of dry weight [g·g -1 DW]). However, 90 minutes of dehydration (0.14 g·g -1 DW) were necessary to obtain seedlings whose qualitative development was equivalent to that of the control embryonic axes.Keywords: seed; dehydration; water content; liquid nitrogen; germinationPistachio is a dicotyledonous angiosperm belonging to the family Anacardiaceae. According to Zohary (1952), the genus Pistacia comprises four sections and 11 species. Pistacia vera L. is the only species producing edible seeds (Joley 1979). With its seeds and its high fodder value, the pistachio is a vital source of income for farmers. However, different types of problems can affect the cultivation of this species including orchard ageing, damage due to pests and diseases. The conservation of Pistacia genetic resources is consequently essential.Seed banks are the most common means of preserving plant genetic resources, at least for species which produce orthodox seeds (i.e. seeds that can withstand dehydration, thus ensuring their long-term viability). For example, pea (Pisum sativum) seeds were shown to be viable after more than 23 years and maize (Zea mays) seeds after 19 years, even though they were stored in ambient conditions (Nagel, Borner 2010). A few 200-years-old seeds of species originating from the Cape floristic region in South Africa were even able to germinate (Daws et al. 2007). In contrast, seeds of other species, called recalcitrant, cannot survive dehydration or storage at low temperatures and consequently cannot be stored for a long period. Most recalcitrant seeds are produced by woody species, shrubs or trees (Li, Pritchard 2009). The influence of conservation on the viability of seeds of P. vera L. is almost unknown. This is a limiting factor for the optimal management of seed stocks by seed producers and for the long-term conservation of P. vera genetic resources. According to Jacquy (1972), pistachio seeds lose 50% of their viability after one year of storage. Plant tissue culture has been used for P. vera L. for ex situ conservation (Ozden-Tokatli et al. 2010). The use of in vitro culture for the conservation of species with recalcitrant seeds has many advantages, including maintenance under aseptic conditions. However, when used for long periods, it has many disadvantages including the risk of genetic variation and...

Long term conservation of embryonic axes of genipap accessions

“…Several factors can cause damages and modifications in the physiological behavior of sensitive seeds during the desiccation process, among them maturation stage and temperature [14]. Benmahioul et al (2015) [1] report the interaction between the water content of embryonic axes during freezing and seed viability.…”

“…These techniques have been successfully used for different explants in Citrus sp. [13]; Coffea arabica L. [9], Hancornia speciosa Gomes [20,25,26], Genipa americana L. [23,24], Pistacia vera L. [1] and Ananas comosus L.) Merr. [31].…”

Advances in Plant Breeding Strategies: Nut and Beverage Crops

“…Several micropropagation studies have been carried out on different pistachio species using various plant materials such as explants excised from in vitro grown juvenile seedlings obtained by germinating the seeds and mature plants, different media culture and different plant growth regulators (PGR). Some problems in the micropropagation process have been reported such as tissue browning in establishment and proliferation steps, shoot tips necrosis (STN), low shoot quality, lack of branching, vitrification and leaf yellowing (Abousalim 1990;Abousalim and Mantell 1994;Akdemir et al 2014;Baninasab and Mobli 2002;Barghchi and Alderson 1985;Benmahioul et al 2009Benmahioul et al , 2012aBenmahioul et al , b, 2015Can et al 2006;Dolcet-San Juan and Clavería 1995;Garoosi et al 2016;Kılınç et al 2015;Marín et al 2016;Mobli and Baninasab 2009;Nezami et al 2015;Nezami-Alanagh et al 2017;Onay 2000a, b;Ozden-Tokatli et al 2005;Picchioni and Davis 1990;Pontikis 1984;Tabiyeh et al 2005Tabiyeh et al , 2006Tilkat and Onay 2009;Tilkat et al 2012).…”

“…The initiation of in vitro cultures from mature pistachio tissue is one of the main obstacles in pistachio tissue culture and several alternative approaches including shoot tip culture, organogenesis, and micrografting have been used to induce rejuvenation (Benmahioul et al 2015;Tilkat et al 2012). A natural problem of the regeneration process is the putative occurrence of somaclonal variations (Benmahioul et al 2015). Regardless of the advantages of the in vitro culture, the occurrence of somaclonal variation in response to in vitro stresses in the regenerates is a serious limitation.…”

Identification D’un Substrat Adequat Pour La Germination Du Fuzz De Canne A Sucre (Saccharum officinarum L.) A Ferkessedougou

“…Cela s'expliquerait par une similarité de ces deux substrats au niveau de leurs structures, textures et composition minérale. De fait, le rôle d'un substrat dans la germination d'une graine est double (Benmahioul et al, 2010). D'abord, il doit avoir une structure permettant de capter et maintenir l'eau en son sein.…”