Mango stem end rot pathogens — Infection levels between flowering and harvest

Abstract

During flowering and fruit set of mango (Mangifera indica L.), colonisation by fungi (Alternaria alternata, Cladosporium cladosporioides, Dothiorella dominicana, Dothiorella mangiferae, Dothiorella sp., Epicoccum purpurascens and Pestalotiopsis sp.) increased as the flowers senesced and young fruit formed.In the third week after flowering, the incidence of Dothiorella dominicana and Dothiorella mangiferae associated with mango fruit-pedicel connection tissue declined coincidentally with early fruit-fall, suggesting that early infections by Dothiorella spp. may cause fruitlet abortion. Dothiorella spp. levels in fruit-pedicel connection tissue remained low for the subsequent 6 weeks, after which they increased. By 16 weeks after flowering, the incidence of Dothiorella spp., determined by isolation from fruit-pedicel connection tissue, was similar to the incidence of stem end rot caused by Dothiorella spp., which developed in fruit harvested at that time. By contrast, the frequency of detection of Dothiorella spp. in peduncle tissue peaked 11 weeks after flowering, when the levels of stem end rot developing in fruit were already similar to the levels recorded in fruit harvested at 16 weeks and later.The results suggest that in fruit and fruit-pedicel tissue, colonisation might arise from Dothiorella spp. occurring endophytically in the peduncle. The earliest indicator of stem end rot incidence at harvest was the infection level in peduncle tissue sampled 11 weeks after flowering. Early assays of peduncle tissue for Dothiorella spp. might prove useful for selecting crops with low stem end rot infection levels.

Harvesting Mango Fruit with a Short Stem-End Altered Endophytic Microbiome and Reduce Stem-End Rot

“…The fruit undergoes dramatic physiological changes during ripening, including increased bioavailability of sugars and amino acids and a decrease in the cell-wall strength and plant-defense mechanisms, which have a significant impact on fruit susceptibility to postharvest decay [7]. These physiological changes modify the endophytic microorganism's environment, probably enabling the pathogenic fungi that present endophytically in the mango stem-end before fruit ripening [2,4], in order to switch to necrotrophic colonization during ripening and to cause SER. Indeed, we found significant changes in both fungal and bacterial communities during storage (Figure 2).…”

“…Among the changes that occur during storage and fruit ripening, we found that the Tremellaceae members decreased in both samples that were harvested with or without stem (Figure 2), some of its members are known as biocontrol yeast (for instance, Cryptococcus laurentii) and they were reported to reduce the postharvest disease of fruits [29]. On the contrary, members of the Dothioraceae and Pleosporaceae increased significantly from Harvest to CS in both mango fruit harvested with and without stems ( Figure 2B); these families contain known SER pathogens of mango, such Dothiorella and Alternaria, respectively [2,4]. Pleosporaceae family (contains Alternaria), which is known to infect fruit in cold storage conditions, being presented in high proportion in the community after CS and significantly decreased after SL in both mango fruit with and without stems.…”

“…Specifically, members of the Dothioraceae were more abundant in the community of fruit without stem when compared to fruit with a stem. This Dothioraceae family contains known mango SER pathogens as Dothiorella dominicana and Dothiorella mangifera [2,4]. Trichocomacea (contains Aspergillus niger) is another fungal family that was in a higher percentage in the community of fruit without stem compared to with stem, which might be used as an indicator of increased decaying processes.…”

“…Because of the high humidity in tropical areas, the primary postharvest disease of mango fruit in those regions is anthracnose, which is caused by Colletotrichum sp. [2]. However, in Israel and other semi-dry areas, mango fruit is exposed to relatively low humidity and almost no rainfall from flowering to fruit development and harvesting.…”

“…SER of mango is caused by a group of fungal pathogens, mainly members of Botryosphaeria genus, such as Dothiorella dominicana, Dothiorella mangiferae, Lasiodiplodia theobromae, Neofusicoccum spp., 2…”