Abstract
Botryosphaeriaceae represents a diverse family of fungi with a cosmopolitan distribution and a wide host range. We studied species diversity and overlap of Botryosphaeriaceae on selected tree species of Anacardiaceae in disturbed (farming or forestry) and undisturbed (isolated and/or protected) ecosystems in the Limpopo and Mpumalanga provinces, South Africa. The disturbed sites resided at Tshikundamalema and Tshipise in Limpopo and the undisturbed sites at Nwanedi and the Mapungubwe National Park in Limpopo and the Kruger National Park in Mpumalanga. Asymptomatic branches were collected from Mangifera indica, Sclerocarya birrea and Lannea schweinfurthii trees in 2017 and 2018. Eleven species were identified using a multi-gene sequencing approach, including Diplodia allocellula, Dothiorella brevicollis, Do. dulcispinae, Do. viticola, Lasiodiplodia crassispora, L. exigua, L. gonubiensis, L. mahajangana, Neofusicoccum parvum, Oblongocollomyces sp. 1 and Oblongocollomyces sp. 2. Ten of the 11 species were identified in undisturbed ecosystems (eight species being unique), while only three species were identified in disturbed ecosystems (one species being unique). Two species were generalists on trees in disturbed and undisturbed ecosystems. Lasiodiplodia mahajangana was the most dominant species as it occurred on the three tree species of Anacardiaceae. Isolates of N. parvum occurred on both S. birrea (a native species) and M. indica (a non-native species) that occurred adjacent to each other in disturbed ecosystems, confirming the ability of this invasive pathogen to cross-infect native and non-native hosts and its abundance in human-disturbed environments. The findings from this study confirm the lack of host specificity for most species of Botryosphaeriaceae. The results also indicate that disturbance through human activity, such as clear-cutting, selective cutting and land-use changes, negatively influences the diversity of the Botryosphaeriaceae.
Highlights
Species of Botryosphaeriaceae are capable of infecting a broad range of monocotyledonous, dicotyledonous and gymnospermous hosts [1]
Asymptomatic branches (20–30 cm long and 2–5 mm wide) showing no prior damage or disease symptoms were collected from three tree hosts, namely S. birrea, M. indica, and, for the first time sampled in South Africa, L. schweinfurthii, in five locations that included disturbed and undisturbed or low disturbance sites
Results obtained from the χ2 test indicated a statistically significant correlation between health status and tree species (p = 0.00)
Summary
Species of Botryosphaeriaceae are capable of infecting a broad range of monocotyledonous, dicotyledonous and gymnospermous hosts [1]. The ability of species of Botryosphaeriaceae to infect multiple hosts facilitates their spread and establishment in new areas, increasing their threat as potential pathogens of woody trees globally [1,10,11]. Once introduced into a new environment, these fungi can spread and infect both related and unrelated hosts [1,9,12]. In South Africa, species of Botryosphaeriaceae have been found overlapping on related tree species of Anacardiaceae [13] and Myrtaceae [7,12] and unrelated hosts in the 4.0/). Several species of Botryosphaeriaceae, including Botryosphaeria dothidea, Lasiodiplodia mahajangana, L. pseudotheobromae, L. theobromae, Neofusicoccum kwambonambiense, N. vitifusiforme, N. luteum and N. parvum have been found on both native and non-native hosts such as Eucalyptus spp. Several species of Botryosphaeriaceae, including Botryosphaeria dothidea, Lasiodiplodia mahajangana, L. pseudotheobromae, L. theobromae, Neofusicoccum kwambonambiense, N. vitifusiforme, N. luteum and N. parvum have been found on both native and non-native hosts such as Eucalyptus spp. [5,6,14], Mangifera indica [13], Malus spp. [4], Pinus spp. [5], Prunus spp. [3,4], Vachellia karroo [15], Sclerocarya birrea [13], Syzygium cordatum [7] and Vitis vinifera [2]
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