Abstract
Background: Plant associated endophytic microbes play an important role in plant’s growth and development. After seed germination, the seed associated endophytes rapidly colonize the seedlings and help in their growth and protection against pathogens. This study was aimed to understand the diversity in the endophytic microbial population associated with the seeds of papaya (Carica papaya) and its wild relatives from Vasconcellea genus (family: Caricaceae). The species of Vasconcellea genus are widely used to introgress virus resistance in cultivated varieties of papaya. Hence, the diversity of seed associated endophytic microbes and their gene functional analysis was carried out through next generation sequencing of the microbial 16S rRNA and ITS sequences. Results: The 16S rRNA amplicon analysis revealed that the number of operational taxonomic units (OTUs) was higher for the endophytic bacteria, ranging between 144–204 when compared to 41–69 OTUs for the endophytic fungi. The bacterial phylum Proteobacteria was the most abundant seed associated phylum, with 64.7–72.8% abundance, across all four species of Caricaceae family, followed by Firmicutes (13.6–26.1%), Patescibacteria (1.1–2%) and Actinobacteria (0.7–2.7%). With respect to the diversity of bacteria by abundance indices, Vasconcellea goudotiana had the highest OTUs of 204, followed by 177 in V. cauliflora, 156 in V. cundinamarcensis, and 144 in C. papaya. The alpha diversity indices and functional analysis revealed the differences in the OTUs and the functional annotations among the above four plant species. The fungal OTUs were in the range of 41–69; however, only a small fraction of them could be taxonomically classified. Conclusion: Our microbiome studies reveal the differences in the seed associated endophytic microbial community across the four plant species of Caricaceae family. This study also unravels the composition of endophytic microbial population associated with the seeds of different plant species of Caricaceae family and their gene functions. It also provides an insight into both culturable and nonculturable endophytic microbes. Further this study reveals that domestication of Carica papaya might have resulted into reduced microbial diversity when compared to their wild relatives from Vasconcellea genus.
Highlights
Introduction iationsPapaya (Carica papaya L.) is a popular fruit crop of tropical and subtropical regions of the world [1] with an annual production of more than 10 million tons [2,3]
Mb) were recorded low for both the internal transcribed spacer (ITS) and the 16S rRNA amplicons in C. papaya when compared to the three Vasconcellea spp
The Trichosporon genus is reported to be a rhizosphere-based plant growth-promoting yeast that can degrade various nitrogen sources and produce auxin [72]. This comparative study of microbiomes associated with the seeds of the cultivated Carica papaya and its four wild relatives from Caricaseae family (Vasconcellea spp.) precisely determines the population structure of the endophytic microbes
Summary
Introduction iationsPapaya (Carica papaya L.) is a popular fruit crop of tropical and subtropical regions of the world [1] with an annual production of more than 10 million tons [2,3]. Papaya fruit is highly nutritive and can fulfill the standard recommended daily requirements of vitamins (A, C, B9 , B3 , B1 , B2 ), iron, potassium, calcium, and fiber [3,6,7] They are cultivated for proteolytic enzymes (papain) derived from the milky latex, used for food, textile, leather and pharmaceutical industries [8,9]. This study was aimed to understand the diversity in the endophytic microbial population associated with the seeds of papaya (Carica papaya) and its wild relatives from Vasconcellea genus (family: Caricaceae). Conclusion: Our microbiome studies reveal the differences in the seed associated endophytic microbial community across the four plant species of Caricaceae family. This study unravels the composition of endophytic microbial population associated with the seeds of different plant species of Caricaceae family and their gene functions
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