REVIEW ARTICLE Stem-end rot in major tropical and sub-tropical fruit species K.O.L.C. Karunanayake and N.K.B. Adikaram Highlights • Stem-end rot (SER) is a most destructive postharvest disease in tropical and sub-tropical fruits. • SER can be caused by several fungal pathogens, Lasiodiplodia theobromae being the most common. • Infection occurs at flowering or fruit development. Fungi may become endophytic in the inflorescence. • Many control options are available where reduction of field infections is key to SER control. Ceylon Journal of Science 49 (Special Issue) 2020: 327-336 DOI: http://doi.org/10.4038/cjs.v49i5.7800 REVIEW ARTICLE Stem-end rot in major tropical and sub-tropical fruit species K.O.L.C. Karunanayake1 and N.K.B. Adikaram2,* 1Department of Botany, The Open University of Sri Lanka, Nawala, Nugegoda, Sri Lanka 2National Institute of Fundamental Studies, Hantana Road, Kandy 20000, Sri Lanka Received: 01/09/2020 ; Accepted: 08/10/2020 Abstract: Stem-end rot (SER) is one of the most destructive fruit loss could be accounted for disease caused by fungal postharvest diseases affecting some tropical and sub-tropical pathogens. Fruit susceptibility to postharvest diseases fruits. The disease is caused by several fungal pathogens, including increases during ripening due to physiological changes Botryosphaeriaceae species. In mango, Dothiorella dominicana, D. and senescence favoring disease development (Prusky mangiferae, Lasiodiplodia theobromae, Phomopsis mangiferae, et al., 2002). Diseases of harvested fruits and mycotoxin Cytosphaera mangiferae, Pestalotiopsis sp. endophytically contamination contribute to major economic losses to colonize the inflorescence in the orchard or field. Fungi may occur grower, wholesaler, retailer and consumer. Management of endophytically in the stem tissue of the trees prior to inflorescence postharvest diseases is needed to avoid losses and increase emergence. During the endophytic stage, the fungi colonize the revenues. phloem and xylem at stem-end and, after fruit ripening, some fungi Anthracnose disease, caused by Colletotrichum become necrotrophic and colonize the fruit pulp causing SER. species, and the stem-end rots often incited by a complex The SER pathogens in other fruit species, including ripe avocado of fungi are considered most common and important or papaya, are not known to undergo an endophytic phase. Stem- postharvest diseases that limit the long-term storage of end rot is a disease that is difficult to control. Preharvest cultural fruit commodities. The stem-end rots are affecting mostly practices and selection of resistant varieties are beneficial to the tropical and sub-tropical fruits. Mango (Mangifera reduce field infections. Studies have shown that numerous control indica L.), avocado (Persea americana), papaya (Carica options, involving cultural, chemical (fungicides, essential oils) papaya), citrus (Citrus sinensis), mangosteen (Garcinia and biological approaches, are available to manage SER through mangostana), rambutan (Nephelium lappaceum L.) and either direct inhibition of fungi or induction of host defenses. carambola are fruits often affected by the stem-end rot These may be used individually or integrated manner. The most disease. common and effective practice for controlling the SER is pre- and postharvest application of synthetic fungicides. With the new Stem-end rots have been investigated extensively tools that are currently available, and expected to emerge, there for understanding the cause/s, the process or the mode is a possibility of a better understanding the host–pathogen or of infection and for formulation of disease management host-microbiota interactions within the stem-end region, leading strategies. In most fruit species, fungal infection takes to newer technologies as alternatives to toxic synthetic fungicides place in the field during flowering, fruit-set or at an early for the management of SER in fruits. stage of fruit maturity. Understanding of the field infection process of stem-end rot and perhaps the epidemiology also Keywords: Postharvest disease, Lasiodiplodia theobromae, is essential to help predict the disease risk during the fruit Neofusicoccum parvum, Endophytic fungi, host-microbiota. season. Predicting plant disease is not only challenging but requires major research efforts. In a complex handling INTRODUCTION system, cultural practices, safer fungicides and biological Production of fruits for human consumption is an important antagonists are integrated to manage postharvest diseases. part of the market economy, requiring many investments. The greatest challenge is to substitute synthetic fungicides Any waste in the field or fruits after harvest, due to physical with safer alternatives to sell a highest quality, residue-free damage, disease or disorders incurs monetary losses. In produce to the consumer. fact, the monetary loss due to damage or loss of fruits after The review will focus on the research findings so harvest is greater than losses in the field because the cost of far accumulated on the stem-end rot disease in tropical harvesting, storage and transport etc. must be added to the and sub-tropical fruit species, with emphasis on mango, cost of production. avocado, papaya, banana and rambutan, including disease Reduction of postharvest losses increases fruit management strategies. availability and represent a critical component of ensuring food security. Most tropical fruits are highly susceptible to postharvest diseases. A larger portion of the postharvest *Corresponding Author’s Email: [email protected] https://orcid.org/0000-0001-8570-1241 This article is published under the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 328 Ceylon Journal of Science 49 (Special Issue) 2020: 327-336 SER in mango causing stem-end rot of mango in Brazil, which brings about significant losses during transportation and storage (Terao Mango (Mangifera indica L.) belongs to the dicotyledonous et al., 2018). Colletotrichum gloeosporioides, Alternaria family Anacardiaceae. The genus Mangifera comprises of alternata, Fusicoccum aesculi, Nattrassia mangiferae, 62 species of which 15 are edible fruits. Mango originated Botryosphaeria spp. and Botrytis cinerea were linked to in the Indo-Burma region and has been cultivated for at SER in mangoes (Ploetz et al., 1994; Abdalla et al., 2003; least 4,000 years in the Indian subcontinent and was spread Slippers et al., 2005; de Oliveira Costa et al., 2010). Using from India to Asia, Africa, Australia, and other parts of the morphological characteristics and DNA sequence data, the world by traders and missionaries (Kwee and Chang, 1985). presence of Lasiodiplodia theobromae (Fig, 2) Fusicoccum Currently, mango is recognized as the most important fruit aesculi and Neofusicoccum parvum. L. theobromae were crop cultivated in 90 tropical and subtropical countries of confirmed in the Assú Valley, Brazil. F. aesculi and N. the world. parvum were in the São Francisco Valley. In fruit Postharvest diseases of mango reduce fruit quality and inoculations, L. theobromae and N. parvum were more cause severe losses resulting in completely unmarketable virulent than F. aesculin (de Oliveira Costa et al., 2010). fruits. Stem-end rot is one of the most important diseases Lasiodiplodia theobromae, Dothiorella spp. C. of mango posing a major threat to the industry, causing gloeosporioides, Phomopsis mangiferae and Pestalotiopsis economic losses. The disease is a serious threat to the mangiferae were identified as stem-end rot (SER) pathogens mango industry because it is difficult to control (de in mango in Sri Lanka with two more Ascomycota species Oliveira Costa et al., 2010). It is more prevalent in fruit namely Xylaria sp. and Nodulisporium sp. from the cv. harvested from older trees (Coates et al., 1993). In Israel, ‘Karuthacolomban’ (Figure 1) in a more recent study using SER causes 30–40% loss of harvested mango fruit during ITS sequence data (Karunanayake et al., 2014; Ekanayake et 2014 (Diskin et al., 2017a). In Sri Lanka postharvest losses al., 2019). Botryosphaeriaceae and Diaporthaceae species, of mango exceed 30 - 40% of which a larger proportion have been reported as pathogens of stem-end rot disease of losses is due to extensive rotting of harvested fruits. around the world, including Botryosphaeria dothidea, Certain mango varieties show resistance to the stem-end Diaporthe pseudomangiferae, Neoscytalidium dimidiatum rot (Karunanayake et al., 2014). The importance of the (Marques et al., 2013; Serrato-Diaz et al., 2014). Diaporthe different fungi in causing mango stem-end rot is influenced species were consistently isolated from mangoes showing by prevailing climatic conditions in the location. stem-end rot in Japan (Ajitomi et al., 2020). The isolates SER pathogens of mango reproduced the original symptoms in healthy mango fruits after inoculation and were re-isolated from the inoculated The predominant pathogens causing this disease are fruits. Based on morphology and a phylogenetic analysis of Neofusicoccum parvum (formerly known as Dothiorella rDNA-ITS, CAL, H3, EF1-α, and TUB, the isolates were domanicana), N. mangiferae (formerly known as classified into two Diaporthe species (Clade I and Clade II) Dothiorella mangiferae), Lasiodiplodia theobromae (Syn. (Ajitomi et al., 2020). Botryodiplodia theobromae), Phomopsis mangiferae,