Influences of stroma development on vegetative growth of Roegneria kamoji

Abstract

Epichloë yangzii Li et Wang is a sexually reproducing, systemic fungal endophyte infecting the host grass Roegneria kamoji (Ohwi) Kent et Chen. To examine the effects of stromatal development on the host, R. kamoji plants harboring E. yangzii were collected from Jiangpu, Nanjing. Differences between stromatal plants and non-stromatal plants in terms of tillering and flowering of the plants, diameter and length of the culms, number and length of the leaves, and senescence of both leaves and culms were investigated from 2010 to 2012. Results indicate that stromal development of E. yangzii promoted the flag leaf growth of stromatal culms, enhanced thousand-seed weight of non-stromatal culms, delayed leaf and culm senescence of both stromatal and non-stromatal culms, but decreased tiller number and inhibited the emergence of inflorescence of the stromatal culms. The overgrowth of fungal hyphae blocked the emergence path and resulted in failure of the emergence of inflorescence of stromatal culms. The decrease in tiller number indicates that influences of stroma occur before plant vernalization, although stromata develop at the early stage of emergence of flag leaf sheath or inflorescence. The delay in leaf and culm senescence on the whole plants indicates signals caused by stromatal development, which can also be transferred to the non-stromatal tillers of the same plant. The mechanisms and significance of these influences, which are mediated by stromal development, need to be investigated in future research.