Effect of arbuscular mycorrhiza on the growth and development of micropropagated Annona cherimola plants

Annona cherimola Mill., cherimoya, is a tropical plantation crop of interest in fruit culture. Micropropagation techniques have been developed due to the need to increase productivity through clonal selection. Because of the mycorrhizal dependence exhibited by this crop for optimal growth and the recognized role of mycorrhiza establishment for the survival and development of most of the plants produced in vitro, the effect of mycorrhiza inoculation on the development of micropropagated plants of Annona cherimola was investigated. Mycorrhizal inoculation was assayed at two different stages of the micropropagation process: (i) immediately after the in vitro phase, before starting the acclimatization period, and (ii) after the acclimatization phase, before starting the post-acclimatization period under greenhouse conditions. Plantlet survival was about 50 % after the acclimatization period. Plant growth and development profited remarkably from mycorrhiza establishment. Most of the arbuscular mycorrhizal fungi (AMF) assayed greatly increased shoot and root biomass and leaf area. Micropropagated Annona plants seem to be more dependent on mycorrhiza formation for optimal growth than plants derived from seeds. The greatest effects of AMF on plant growth were observed when they were introduced after the acclimatization period

Effect of arbuscular mycorrhiza on the growth and development of micropropagated Annona cherimola plants

vokArbuskelimykorritsasienten vaikutus mikrolisätyn annoonan (Annona cherimola) kasvuun ja kehityksee

Arbuskelimykorritsasienten vaikutus mikrolisätyn annoonan (Annona cherimola) kasvuun ja kehitykseen

Annona cherimola Mill., cherimoya, is a tropical plantation crop of interest in fruit culture. Micropropagation techniques have been developed due to the need to increase productivity through clonal selection. Because of the mycorrhizal dependence exhibited by this crop for optimal growth and the recognized role of mycorrhiza establishment for the survival and development of most of the plants produced in vitro, the effect of mycorrhiza inoculation on the development of micropropagated plants of Annona cherimola was investigated. Mycorrhizal inoculation was assayed at two different stages of the micropropagation process: (i) immediately after the in vitro phase, before starting the acclimatization period, and (ii) after the acclimatization phase, before starting the post-acclimatization period under greenhouse conditions. Plantlet survival was about 50 % after the acclimatization period. Plant growth and development profited remarkably from mycorrhiza establishment. Most of the arbuscular mycorrhizal fungi (AMF) assayed greatly increased shoot and root biomass and leaf area. Micropropagated Annona plants seem to be more dependent on mycorrhiza formation for optimal growth than plants derived from seeds. The greatest effects of AMF on plant growth were observed when they were introduced after the acclimatization period.Annona eli kirimoija (Annona cherimola Mill.) on kiinnostava trooppinen hedelmäkasvi. Espanjassa kehitettiin kasvin mikrolisäystä, että kasvin kloonivalintaa voitaisiin tehdä sadontuottokyvyn parantamiseksi. Annona tarvitsee mykorritsaa saavuttaakseen optimaalisen kasvun. Aikaisemmissa kokeissa on todettu mykorritsasiirrostuksen lisäävän annoonan pikkutaimien henkiinjäämistä ja kehitystä. Tämän tutkimuksen tavoitteena oli selvittää arbuskelimykorritsasienten siirrostuksen vaikutusta mikrolisätyn annoonan kasvuun ja kehitykseen. Kasvit siirrostettiin kahtena ajankohtana, joko välittömästi taimien in vitro -vaiheen jälkeen ennen sopeuttamista jatkoviljelyolosuhteisiin tai sopeuttamisjakson jälkeen. Sopeuttamisvaiheen jälkeen taimien eloonjäämisprosentti oli vain n. 50. Mykorritsa paransi taimien kasvua ja kehitystä. Useimmat käytetyt sienikannat lisäsivät huomattavasti versojen ja juurten biomassaa sekä lehtialaa. Mikrolisätyillä Annona-taimilla näyttää olevan suurempi riippuvuussuhde mykorritsan kanssa kuin siemenistä kasvatetuilla taimilla. Mykorritsasienten vaikutus oli vahvin silloin, kun siirrostus tehtiin sopeuttamisjakson jälkeen

Micropropagation of Asparagus macrorrhizus, a Spanish endemic species in extreme extinction risk

Asparagus macrorrhizus: is a new species, which has been recently described. It is limited to the area surrounding the “Mar Menor” lagoon, in Murcia (Spain), and is the only “Critically Endangered” species of the genus Asparagus. Despite being protected, the number of plants has decreased in the last years due to the urbanization of its natural habitat. This species is a valuable genetic resource for asparagus breeding because of its special characteristics. So, the development of a micropropagation protocol is crucial to its conservation and use in breeding programs. The micropropagation protocol from asparagus rhizome buds previously developed by our research group has been adapted for A. macrorrhizus. Rhizome buds of A. macrorrhizus were extracted, disinfected, and then cultured on Asparagus Rhizome Bud Medium (ARBM) consisting of MS medium supplemented with 0.3 mg l NAA, 0.1 mg l KIN, 2 mg l ancymidol and 6% sucrose. A percentage of 69.7 ± 8.0% of the rhizome buds developed shoots, but only 17.4 ± 7.9% of them rooted. To increase this low rooting rate, the shoots were cultured on Macrorrhizus Rooting Media (MRM) supplemented with three different concentrations of IBA. The highest rooting rate (55.0 ± 7.9%) was reached when shoots were incubated in MRM-2 consisting of MS medium supplemented with 2 mg l IBA and 4% sucrose. The acclimatization rate of the micropropagated plantlets was 90%. The method developed in this study allows the micropropagation of A. macrorrhizus, offering a new option to preserve this almost extinct species.Authors would like to thank to the Official Nursery of the Directorate General for the Environment belonging to the Council of Agriculture and Water of the Region of Murcia (Spain) for facilitating the plants of A. macrorrhizus used in this work. This study was funded by “Junta de Andalucía” (Project of Excellence AGR3648). INMIBO Publication No. 216. Doctor Regalado Gonzalez is a Post-Doctoral Fellow at CONICET.Peer Reviewe

Production of "super-males" of asparagus by anther culture and its detection with SSR-ESTs

Anther culture is used to develop asparagus “super-male” (di-haploids) in asparagus, which can be used to develop “all-male” varieties, by crossing them with suitable females; their progenies will be formed only by males which is advantageous for producers. This report describe a new anther culture protocol adapted to “Morado de Huétor”, a Spanish tetraploid landrace, and studied the different factors involved in callus proliferation success from anther explants such as the microspore development stage, or the type of stress used to induce the symmetric division of the microspores, to obtain a high success rate (90 %). For plantlets regenerates from anther culture (PRACs) regeneration we develop a proliferation media supplemented with a combination of pCPA and BA able to induce callus proliferation and plantlet regeneration in the same step in a 50 % of calli, simplifying the procedure. The high percentage of heterozygous male recovery, originated from somatic cells, is an important problem in the anther culture, and to elucidate the origin of PRACs we have combined different tools: ploidy analysis, characterization with the linked sex-marker Asp1-T7 and with EST-SRRs. We can establish that 50 % of PRACs obtained in this work were regenerated from diploid microspores of “Morado de Huétor”, regenerating diploid, di-diploid and tetra-diploid plantlets. The di-diploids males (MMmm) would generate a ratio male:female of 5:1 (83.3 %) and the tetra-diploid males (MMMMmmmm) a ratio male:female of 69:1 (98.6 %), so the tetra-diploid males could be considered “super-males” and be used to develop “all-male” varieties of “Morado de Huétor”.This work was funded by the Project of Excellence AGR3648, managed by the Junta de Andalucia (Spain).Peer reviewe