Challenges of in vitro conservation of Сitrus germplasm resources

Abstract

The main problems of establishment a slow growth in vitro collection of citrus and other tree crops cultivars are high degree of fungal contamination of bud explants and low growth potential of shoots. In this regard, the aim of current research is to assess the efficiency of decontamination procedure and the possibility of tissue culture initiation and slow growth conservation of valuable lemon cultivars. The best results of surface sterilization were obtained using immersion solutions of 0.3 % Veltolen – 25 minutes or 10 % Domestos – 25–30 minutes. In these treatments, 27.7–33.0 % of aseptic explants were obtained, respectively. However, after the third subculture, the yield of aseptic viable explants decreased till 10 % as a result of secondary contamination by endophytic fungi. The addition of biocide (“Gavrish”) in a nutrient medium at a concentration of 1 ml/l helped to increase the yield of aseptic viable explants till 50 %. However, after the third subculture the photosynthetic activity and the pigments content as well as growth rate decreased. Plants dropped yellowish leaves and eventually died. Thus, 37.35 % of plantlets survived after 8 months of conservation, and only 14.6 % survived after 10 months. Even after the third month of conservation significant decrease in the viability index and the coefficient of photosynthetic activity occurred in plants. Chlorophyll a in leaves decreased from 1.59 to 1.14 mg/g during 12 months in vitro conservation. The similar tendency observed on clorophyll b and carotenoids content. The experiments were carried out for 5 years using different lemon cultivars and other citrus varieties and cultivars. Thus, micropropagation and slow growth in vitro conservation of valuable lemon cultivars are still problematic and requires new technical solutions due to the low growth potential of plantlets raised from the mature buds that is consistent with the data of other researchers.

Statistical estimates of multiple transcription factors binding in the model plant genomes based on ChIP-seq data

“…Note the detailed databases on genome-wide TF binding developed earlier – TRRD, GTRD, and HOCOMOCO [ 31 , 32 ]. However, data on TF binding in plants are rather scattered [ 21 , 22 , 30 , 33 ]. For comparison with predicted binding sites in Arabidopsis we used AthaMap resource [ 34 ] and JASPAR [ 35 ].…”

New evidence for in vitro conservation of nodal segments of the passion fruit ‘UENF Rio Dourado’ (Passiflora edulis Sims)

“…The reduction in salt concentration to 25% MSM was also shown to be efficient in the slow growth of nodal segments of P. suberosa, with 100% survival achieved after six months and 83% after one year of growth (Garcia et al, 2011). Reductions in mineral salt concentrations in the culture medium have been widely studied in the slow growth of several other fruit species, such as pineapple (Silva et al, 2016), citrus (Gorshkov et al, 2019), and grape (Tehrim & Sajid, 2011).…”

Determination of the best culture medium for establishment, propagation and conservation in vitro of citrus rootstocks

“…Propagation via seeds has several advantages, such as the production of plantlets free of diseases and with the same genetic make-up as the mother plant when generated by apomixis (GEORGE & DEBERGH, 2008). This asexual reproduction method occurs in the Citrus genus, for which obtaining plants in vitro is generally from seeds due to the complexity of regenerating apical meristems, a vegetative propagation method that guarantees clonal cleaning of genotypes, and also because of the difficulty of decontaminating and regenerating mature buds, as described by GORSHKOV et al (2019) in their study of different lime genotypes [Citrus limon (L.)…”