TABLE 2.

Estimates of endophyte biomass in infected ryegrass tissue

Tissue sectiona	Area (mm2) of cross section of individual hyphae (no. of observations)b	Estimated fungal dry wt/mg dry wt of grass tissue (μg)c
Lower emerging leaf	1.95 × 10−6 (10)	0.386
Upper emerging leaf	2.21 × 10−6 (9)	0.120
Blade innermost mature leaf	2.73 × 10−6 (13)	0.291
Blade middle mature leaf	3.58 × 10−6 (10)	0.269
Blade outermost mature leaf	3.49 × 10−6 (9)	0.443
Sheath innermost mature leaf	2.43 × 10−6 (34)	1.080
Sheath outermost mature leaf	4.28 × 10−6 (42)	2.045

^aAll data were obtained by using tillers with three mature leaves. 

^bValues were determined by using electron micrographs as described in Materials and Methods. The values are for individual hyphae. 

^cThis value was calculated as follows. The total length of mycelium in individual grass tissue sections (sections correspond to sections shown in Fig. 1) of tillers with three mature leaves was calculated as the number of hyphae in the section times the length of the section. These values were then multiplied first with the hyphal cross sections shown in this table and then with 1.1 g/cm³ (16) to arrive at an estimate of the fresh weight of the mycelium and finally with 0.3 (48) to convert the fresh weight to dry weight. These values were divided by the dry weight of the grass tissue section. The values shown for lower and upper emerging leaves are averages of all upper and lower emerging leaf sections of five tillers with three mature leaves. Blade values are averages of all lower- and upper-blade values from the same five tillers, and sheath values are averages of all lower- and upper-blade values from the same five tillers.