Extreme physiology: Biomass and transcriptional profiling of three abandoned Agave cultivars

Agaves have been used for centuries as a feedstock in dryland areas for fibers, food, and beverages, and have enormous potential for biofuel production. Brazil is the world's largest producer of Agave fiber (sisal). However, since the development of synthetic fibers, the national investment in Agave research has decreased drastically, leading to the cessation of the country's breeding programs. What is left of the Brazilian elite cultivars were planted at a germplasm bank in the middle of the semiarid. Surprisingly, after 7 years of abandonment, the plants were still healthy and did not show any clear signs of stress. Here, we aimed to investigate how these plants managed to cope with this environment and the molecular basis of their biomass traits. We assembled the transcriptomic atlas of Agave sisalana, Agave fourcroydes, and Agave hybrid 11648 ((A. amaniensis x A. angustifolia) x A. amaniensis). We observed that the cultivars activated a highly overlapping set of stress response genes, which were the most expressed transcripts. Also, raffinose was detected at high concentrations, possibly acting as an osmolyte, though differences at its biosynthesis have been found depending on cultivar. Finally, we observed differences in recalcitrance that could be attributed to lignin composition and its biosynthetic pathway. Our data contribute new insights that can help molecular breeders to correspond to emerging expectations for Agave as biorenewables feedstocks for dryland areas.

Automated summary

Agaves, traditionally used in dryland areas for various purposes, still hold potential for biofuel production despite reduced research investment due to synthetic fiber development. In Brazil, elite Agave cultivars remain healthy after years of abandonment, activating stress response genes and expressing high levels of raffinose. Differences in lignin composition and biosynthetic pathway contribute to variations in recalcitrance among cultivars, offering new insights for molecular breeders aiming to utilize Agaves as biorenewables feedstocks.