Utilization of somatic fusion techniques for the development of HLB tolerant breeding resources employing the Australian finger lime (Citrus australasica)

Abstract

The Australian finger lime is a unique citrus species that has gained importance due to its unique fruit characteristics and perceived tolerance to Huanglongbing (HLB), an often-fatal disease of citrus trees. In this study, we developed allotetraploid finger lime hybrids and cybrids by utilizing somatic cell fusion techniques to fuse diploid ‘OLL8’ sweet orange or ‘Page’ tangelo callus-derived protoplasts with finger lime (FL) mesophyll-derived protoplasts. Six somatic fusions were regenerated from the ‘OLL8’ + FL fusion, while three putative cybrids were regenerated from the ‘Page’ + FL fusion. Ploidy levels and nuclear-expressed sequence tag derived simple sequence repeat (EST-SSR) markers confirmed the somatic hybrid production, and mitochondrial DNA primer sets confirmed the cybrid nature. Several trees produced by the somatic fusion remained HLB negative even after 6 years of growth in an HLB-endemic environment. Pathogenesis related (PR) and other genes that are often upregulated in HLB-tolerant trees were also upregulated in our somatic fusions. These newly developed somatic fusions and cybrids could potentially be used as breeding parents to develop the next generation of improved HLB-tolerant rootstocks and scions.

Comparative Analysis of Physicochemical Properties and Storability of a New Citrus Variety, Yellowball, and Its Parent

“…Numerous citrus varieties are being newly developed to improve citrus quality globally [11][12][13][16][17][18]. However, the quality of many of these varieties has not been objectively evaluated.…”

Genomic Instability in Somatic Hybridization between Poncirus and Citrus Species Aiming to Create New Rootstocks

“…Therefore, confirmation that our somatic hybrids inherited a complete set of genes of P. trifoliata is not sufficient to conclude that all favorable phenotypic traits of trifoliate orange are transmitted to the somatic hybrids. Phenotypic evaluations demonstrated that CTV resistance of P. trifoliata [18], HLB resistance of M. australasica [127], and adaptation to calcareous soils of C. reticulata [18] were successfully inherited in allotetraploid somatic hybrids. Further extensive phenotypic and genomic studies including transcriptome, small RNA, epigenomome, and mobilome should be conducted to understand the implication of inter-generic somatic hybridization in the functional genomic of the somatic hybrids.…”

Isolation and binary fusion of taro (Colocasia esculeneta (L) Schott.) protoplast: Towards developing somatic hybridization protocol as an alternative to sexual hybridization

“…Somatic hybrids plants are regenerated through embryogenesis or organogenesis. Plant protoplast fusion has successfully been used to transfer disease resistance and other qualitative traits (Dutt et al, 2021). Indeed, availability of reproducible protoplast isolation, fusion and plant regeneration protocols will open new opportunities for developing new or improving SSA taro cultivars.…”