Macrophomina vaccinii Y. Zhang ter & L. Zhao

Zhao, Lin, Cai, Jing, He, Wei & Zhang, Ying, 2019, Macrophominavaccinii sp. nov. causing blueberry stem blight in China, MycoKeys 55, pp. 1-14 : 1

Macrophomina vaccinii Y. Zhang ter & L. Zhao sp. nov. Figure 2

Holotype.

CHINA, Fujian province, Nanping city, Jianyang district, Huilong village, from blighted stem of southern high bush ( Vaccinium corymbosum × V. darrowii ), 26 Feb. 2018, L. Zhao (HMAS 255479): ex-type living culture, CGMCC 3.19503.

Etymology.

from " Vaccinium ", in reference to the host genus.

Description.

Sexual stage not observed. Asexual stage: Sclerotia developing on SNA, black, smooth, hard, 40-100 µm diam. Conidiomata pycnidial, dark brown to black, solitary or gregarious, up to 400 µm diam., each opening by a central ostiole. Conidiogenous cells lining the inner surface of the conidioma, hyaline, subcylindrical, each proliferating several times percurrently near the apex, 9-16 × 3-4 µm, young conidiogenous cells each covered by a mucous layer that extends over the apex of the developing conidium. Conidia ellipsoid to obovoid, smooth, (18 –)20–29(– 33) × (8 –)9–11(– 12) µm (av. 24.8 × 10.1 µm, n = 60, L/W ratio = 2.5, range from 2.3 to 2.8), immature conidia hyaline, enclosed in a mucous sheath, that upon dehiscence encloses the top half of the conidium, transformed into two lateral tentaculiform, apical mucoid appendages (type C; Nag Raj 1993), no pigmented conidia observed after 30 days incubation. Microconidia aseptate, hyaline, smooth, guttulate to granular, straight to curved, ellipsoid to subcylindrical to irregular, 5 –9(– 10) × 3-5 µm.

Culture characteristics.

Colonies on MEA at 25 °C in darkness, with even margins, sparse aerial mycelia. On MEA buff, turning pale olivaceous to olivaceous-black with dense, black sclerotial masses. Colonies reaching 58.6 mm on MEA after 2 d in the dark at 25 °C.

Additional specimens examined.

CHINA, Fujian province, Nanping city, Jianyang district, Huilong village, from blighted stem of southern high bush ( Vaccinium corymbosum × V. darrowii ), 26 February 2018, L. Zhao (Paratype, HMAS 255480): living culture, CGMCC 3.19505; (HMAS 255481): living culture, CGMCC 3.19510.

Note.

Based on phylogenetic analysis, M. vaccinii and M. phaseolina formed a well-supported clade. Morphologically, the wider conidia of Macrophomina vaccinii can be distinguishable from M. phaseolina ((8 –)9–11(– 12) µm (av. 10.1 µm) vs. (6 –)8(– 9) µm (av. 8 µm)) ( Sarr et al. 2014). In addition, the larger-sized pycnidia of M. vaccinii are also distinguishable from M. phaseolina (up to 400 µm diam. vs. up to 300 µm diam.) ( Sarr et al. 2014). A comparison of the 264 nucleotides across the tef1-α gene region of M. vaccinii and M. phaseolina (CBS 227.33) reveals 5 base pair differences (1.9%) (Table 3).