Steve Wylie

Plants are constantly being challenged with various biotic and abiotic stresses throughout their life cycle that exert profound deleterious effects on growth, development and health. Plants employ various physiological, biochemical and molecular mechanisms to combat these stress factors. Microorganism-mediated plant stress tolerance, particularly plant drought tolerance, is important in the study of plant–microbe interactions. Although relatively less well-known, fungal endophyte-mediated plant drought tolerance has been described for several cases. Unlike mycorrhizal fungi, non-mycorrhizal fungi may mediate the effects of water stress by adjusting, regulating or modifying plant physiological, biochemical and metabolic activities. We review the evidence for fungal endophyte-mediated plant drought tolerance and mechanisms.

Viruses have traditionally been seen as pathogens of plants and animals. Recent research has shown that most viruses induce no pathology in natural plant hosts and in some cases they may be of benefit in reducing damage from both biotic and abiotic stressors. New technologies are revealing that viruses are far more abundant and diverse than previously known, and unexpected roles as symbionts and as sources of genetic raw material for evolution are informing a new appreciation of the roles plant viruses play in nature.

Plant transformation is a key methodology that has allowed transfer and expression of novel genes for the improvement of economically important plant species as well as enquiry into deeper questions about the function of plant genes. For many plant species, stable transformation remains difficult or impossible. Where it is possible, there is usually a need for expensive resources such as laminar flow hoods, controlled environment growth rooms and highly skilled practitioners. In addition, there are often problems related to combining efficient plant regeneration with gene transfer as transfer techniques are carried out in undifferentiated cell cultures. Low transformation efficiency, instability of transgene expression, somaclonal variation and inability to regenerate whole plants are common problems.