4.2 Infection of T. laevis and T. controversa in anther cells
The common, dwarf, and other related bunt fungi have a long infection and development process from seedling to grain filling (Lu et al., 2015; Nguyen et al., 2019; Bokore et al., 2019). In fact, the mycelium that develops in the infected seedling remains spares until a massive proliferation in floral tissue (Ghareeb et al., 2011). In the present study, we inoculated wheat spikes with mycelia of T. laevis andT. controversa to study the effects of infection on the development of wheat anthers. We tracked the prevalence of T. laevis or T. controversa mycelia into somatic and reproductive anther cells for understanding the process of infection. Hyphae proliferate finally into the pollen grains and releasing of these infected pollens for pollination, is critical for normal plant reproduction and produced seeds is transformed into a generally spherical sorus termed a bunt ball that contains dark-colored mass of teliospores (Goates & Peterson, 1993). Our results showed that hyphae of T. laevis was well established on EPI cells at 800 µm long and rupture the cell structure (Figure 4A-C ). EPI cells are the most earliest infected anther cells from filaments, from which the hyphae spread to other connective cells. Thus, the nearest next cell of EPI is EN, which was infected at 1220 µm long anther. Similarly, TA and PG cells were infected at 1300 µm and 1520 µm. By comparison with control anthers, TA should be disappeared at 1300 µm, but which was visible at 1300 µm (Figure 4G-I). We conclude that the pathogen prevents normal development of TA and PG which interrupts the production of signals that results in the development of reproductive cells (Walbot & Skibbe, 2010; Li, 2013). The mechanism of T. controversainfection was similar to that of T. laevis , but delayed differentiation in TA and PG compared to control. TA was observed at 2100 µm and PG was also present on the 2100 µm long anthers (Figure6G-I ) (Hu et al., 2002; Schirawski et al., 2007).