Biotechnology can complement conventional breeding and expedite the mango improvement programmes. Studies involving in vitro culture and selection, micropropagation, embryo rescue, genetic transformation, marker-assisted characterization and DNA fingerprinting, etc. are underway at different centers worldwide. In vitro culture and somatic embryogenesis of several different genotypes have been achieved. The nucellus excised from immature fruitlets is the appropriate explant for induction of embryogenic cultures. High frequency somatic embryogenesis has been achieved in some genotypes; however, some abnormalities can occur during somatic embryo germination. Embryo rescue from young and dropped fruitlets can improve the hybridization success in a limited flowering season. Protocols for protoplast culture and regeneration have also been developed. In vitro selections for antibiotic tolerance and fungal toxin resistance have been very promising for germplasm screening. Genetic transformation using Agrobacterium tumefaciens has been reported. Genes that are involved with fruit ripening have been cloned and there have been attempts to deliver these genes into plants. DNA fingerprinting and studies on genetic diversity of mango cultivars and Mangifera species are also being conducted at several research stations. The purpose of this review is to focus upon contemporary information on biotechnological advances made in mango. It also describes some ways of overcoming the problems encountered during in vitro propagation of mango.

Research review paper Biotechnological advances in mango (Mangifera indica L.) and their future implication in crop improvement — A review

Mango (Mangifera indica L.) is known as the ‘king of fruits’ for its rich taste, flavor, color, production volume and diverse end usage. It belongs to plant family Anacardiaceae and has a small genome size of 439 Mb (2n = 40). Ancient literature indicates origin of cultivated mango in India. Although wild species of genus Mangifera are distributed throughout South and South-East Asia, recovery of Paleocene mango leaf fossils near Damalgiri, West Garo Hills, Meghalaya point to the origin of genus in peninsular India before joining of the Indian and Asian continental plates. India produces more than fifty percent of the world’s mango and grows more than thousand varieties. Despite its huge economic significance genomic resources for mango are limited and genetics of useful horticultural traits are poorly understood. Here we present a brief account of our recent efforts to generate genomic resources for mango and its use in the analysis of genetic diversity and population structure of mango cultivars. Sequencing of leaf RNA from mango cultivars ‘Neelam’, ‘Dashehari’ and their hybrid ‘Amrapali’ revealed substantially higher level of heterozygosity in ‘Amrapali’ over its parents and helped develop genic simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers. Sequencing of double digested restriction-site-associated genomic DNA (ddRAD) of 84 diverse mango cultivars identified 1.67 million high quality SNPs and two major sub-populations. We have assembled 323 Mb of the highly heterozygous ‘Amrapali’ genome using long sequence reads of PacBio single molecule real time (SMRT) sequencing chemistry and predicted 43,247 protein coding genes. We identified in the mango genome 122,332 SSR loci and developed 8,451 Type1 SSR and 835 HSSR markers for high level of polymorphism. Among the published genomes, mango showed highest similarity with sweet orange (Citrus sinensis). These genomic resources will fast track the mango varietal improvement for high productivity, disease resistance and superior end use quality.

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Origin, Diversity and Genome Sequence of Mango (Mangifera indica L.)

Humans have domesticated diverse species from across the plant kingdom, yet much of our foundational knowledge of domestication has come from studies investigating relatively few of the most important annual food crops. Here, we examine the impacts of domestication on genetic diversity in a tropical perennial fruit species, mango (Mangifera indica). We used restriction site associated DNA sequencing to generate genomic single nucleotide polymorphism (SNP) data from 106 mango cultivars from seven geographical regions along with 52 samples of closely related species and unidentified cultivars to identify centers of mango genetic diversity and examine how post-domestication dispersal shaped the geographical distribution of diversity. We identify two gene pools of cultivated mango, representing Indian and Southeast Asian germplasm. We found no significant genetic bottleneck associated with the introduction of mango into new regions of the world. By contrast, we show that mango populations in introduced regions have elevated levels of diversity. Our results suggest that mango has a more complex history of domestication than previously supposed, perhaps including multiple domestication events, hybridization and regional selection. Our work has direct implications for mango breeding and genebank management, and also builds on recent efforts to understand how woody perennial crops respond to domestication.

/pdf/population-genomic-analysis-of-mango-mangifera-indica-3d669t8cxt.pdf

Population genomic analysis of mango (Mangifera indica) suggests a complex history of domestication

Uso de marcadores moleculares en plantas; aplicaciones en frutales del tropico. En el presente trabajo se realizo una revision bibliografica sobre el uso de marcadores moleculares en plantas, con enfasis en el uso de los mismos en especies frutales del tropico. Comprende aspectos relativos al uso e importancia, ventajas, desventajas y caracteristicas, evolucion de las principales metodologias de marcaje a traves del tiempo y una explicacion de las tecnicas de uso mas frecuente. Por ultimo, se presenta una lista de las publicaciones mas relevantes hasta el ano 2005. En esta se indican los autores, la especie estudiada, el objetivo del trabajo, la tecnica empleada asi como los principales resultados obtenidos.

Uso de marcadores moleculares en plantas; aplicaciones en frutales del trópico

Morphological and molecular characterization and evaluation of mango germplasm: An overview

SummaryFifty mango cultivars were screened using Randomly Amplified Polymorphic DNA (RAPD) markers with decamer primers of arbitrary sequence. Out of the 80 primers screened, ten were selected which gave 139 clear and bright fragments. A dendrogram based on Jaccard’s co-efficient of similarity implied a moderate degree of genetic diversity among the cultivars used for experimentation. The hybrids which had one parent in common were placed together. In the cluster, alternate bearers and regular bearers formed separate groups, and the members in each group were very closely linked. Another analysis based on Pearson's co-efficient of similarity revealed a high degree of genetic diversity. In both the analyses, ‘Mulgoa’ was found to be very distinct. This study showed clearly that cultivars from South India unveiled maximum diversity and indicated the potential of RAPD markers for the identification and management of mango germplasm for breeding purposes.

Theertha Prasad

Papers

Estimation of genetic diversity of commercial mango (Mangifera indica L.) cultivars using RAPD markers