Microbiome Alterations Are Correlated with Occurrence of Postharvest Stem-End Rot in Mango Fruit

Abstract

During storage and ripening, mango fruit develop stem-end rots (SER) that reduce quality, causing significant losses of harvested fruit. The presented results indicate that pathogens, endophytically colonizing the fruit’s stem end, awaken during fruit ripening and cause SER. The main pathogens causing SER in mango grown in Israel were found to be Alternaria alternata and Lasiodiplodia theobromae. Confocal analysis of the sliced stems indicated that the pathogens endophytically colonize the phloem of the fruit’s stem end; they branch into the fruit parenchyma when the pathogen switches to its actively pathogenic stage. We show that the stem ends are also colonized by other microorganisms, including fungi, yeast, and bacteria, which do not cause any apparent symptoms and are considered as true endophytes. Stem-end microbiomes of red (resistant) compared with green (susceptible) mango stored at optimal and suboptimal temperatures were deep sequenced for fungi and bacteria using internal transcribed spacer and 16S, respectively. Our results showed that both fungal and bacterial community changes are dependent on fruit peel color, storage duration, and storage temperature. The stem-end microbiota seems to be very dynamic in terms of interactions and changes. For example, in susceptible fruits, as green mango compared with red mango and in fruit after storage compared with harvested fruit, the abundance of Alternaria (Pleosporaceae) pathogens increased. This increase in pathogenic fungi was correlated with the increased occurrence of SER. In those two scenarios, before the rot developed, the increased amount of fungi was correlated with an increased abundance of chitin-degrading Chitinophagaceae bacteria. In summary, our results show that various conditions modify the microbial community at the stem end and can reduce postharvest SER.

Glycosylated flavonoids: fruit's concealed antifungal arsenal

“…Red mango fruit, which contains high concentrations of anthocyanins and flavonols, are more resistant to various pathogens, including Colletotrichum gloeosporioides (Sivankalyani et al, 2016a,b;Diskin et al, 2017;Sudheeran et al, 2018; Fig. S4).…”

Fungal Microbiota of Sea Buckthorn Berries at Two Ripening Stages and Volatile Profiling of Potential Biocontrol Yeasts

“…6-Methyl 5-hepten-2-one (20), 6-methyl-5-hepten-2-ol (23), propionic acid (25) and 2-methylpropionic acid (26) were unique volatiles released by C. wieringae, while only ethyl 3-methylbutanoate (7) was specific for A. pullulans ( Figure 6B, Table 2). Ethyl butanoate (5), ethyl 2-methylbutanoate (6), 3-methylbutyl propionate (13), ethyl hexanoate (16), ethyl octanoate (21), and 2-phenylethyl propionate (31) were exclusively present in volatile blends of H. uvarum yeasts, and phenylmethanol (32) was unique for M. pulcherrima ( Figure 6B, Table 2).…”

“…The biogeographic distribution of microbiota communities has been revealed on apple, blackcurrant, and grape [21,28]. The effect of the ripening stage on the development of the microbial population was investigated in grapes, mango, nectarines and plums [8,[29][30][31]. Analysis of grape bacterial microbiota defined changes in the structure and size of the population occurring during the ripening process.…”

Postharvest Fungicide for Avocado Fruits: Antifungal Efficacy and Peel to Pulp Distribution Kinetics

“…Lasiodiplodia theobromae strain Avo 62 was isolated from rotten "Hass" avocado fruit grown in Israel and used for this study. The purified single spore cultures of L. theobromae strain Avo 62 was identified by sequencing the amplicon of the PCR amplification with ITS1 and ITS4 primers and was identified as a stem-end rot (SER) causal agent by Koch's postulate on avocado fruit [11,12]. The fungi were maintained on potato dextrose agar (PDA, Difco Ltd., Le Pont-de-Claix, France) at 22 • C.…”