Molecular and metabolic changes of cherelle wilt of cacao and its effect on Moniliophthora roreri

• Cherelle wilt changed expression of ESTs related to osmotic stress and hormones.
• Moniliophthora roreri infection caused little alteration of cherelle physiology.
• M. roreri response to senescence associated with wilt was delayed.
• There is no indication that M. roreri causes cherelle wilt.

Young Theobroma cacao pods, known as cherelles, are commonly lost to physiological thinning known as cherelle wilt. Cherelles are susceptible to frosty pod rot caused by Moniliophthora roreri. We studied the cherelle wilt process and its impact on M. roreri infection using microscopic, metabolite, and gene expression analyses. Wilt was associated with increased levels of tricarboxylic acid cycle intermediaries and decreased levels of major metabolites. Expression changes of cacao ESTs in response to wilt suggest induction of the polyamine, ethylene, and jasmonic acid biosynthetic pathways and regulation of abscisic acid and cytokinin levels. M. roreriinfection caused little alteration of cherelle physiology. M. roreri responded to the late stage of wilt by altering the expression of M. roreri ESTs associated with metabolite detoxification and host tissue degradation. The environment of the wilting cherelles may truncate the disease cycle of frosty pod rot, by limiting M. roreri sporulation and stopping the lifecycle.