Botryosphaeriaceae partially overlap on asymptomatic and symptomatic tissues of Anacardiaceae in agroecosystems and conservation areas in northern South Africa

Abstract

Members of the Botryosphaeriaceae are well-known endophytes and stress-related pathogens. We recently characterised the diversity of Botryosphaeriaceae in healthy tissues of three tree species in the Anacardiaceae, namely Sclerocarya birrea, Mangifera indica and Lannea schweinfurthii. Here we ask how that diversity compares with the Botryosphaeriaceae diversity associated with dieback on those tree species. Samples were collected from agroecosystems (Tshikundamalema and Tshipise in Limpopo) and conservation areas (Nwanedi and the Mapungubwe National Park in Limpopo and the Kruger National Park in Mpumalanga) ecosystems. Species were characterised using multigene sequence data and morphological data. Diplodia allocellula, Dothiorella brevicollis, Do. viticola, Lasiodiplodia crassispora, L. mahajangana and Neofusicoccum parvum occurred on both asymptomatic and symptomatic samples. Dothiorella dulcispinea, L. gonubiensis and L. exigua, as well as a previously unknown species described here as Oblongocollomyces ednahkunjekuae sp. nov., only occurred in asymptomatic branches. An interesting aspect of the biology of O. ednahkunjekuaeae is that it appears to be adapted to higher temperatures, with an optimum growth at 30 °C, and faster growth at 35 °C than at 25 °C. Lasiodiplodia pseudotheobromae only occurred in symptomatic branches. Neofusicoccum parvum was notably absent from conservation areas, and in agroecosystem it was most common on M. indica. Only L. crassispora and L. mahajangana overlapped on all three tree species and were the dominant species associated with dieback. These results show that not all Botryosphaeriaceae occurring asymptomatically in an area contribute equally to disease development on a related group of hosts, and that environmental disturbance plays a significant role in the distribution of N. parvum.