Asexually propagated Agave tequilana var. azul exhibits variation in genetic markers and defence responses to Fusarium solani.

Agave (Agave tequilana var. azul) is considered a crop with low genetic diversity because it has been propagated vegetatively for centuries for commercial purposes, and consequently, it could be equally susceptible to pests and diseases. However, the present study employs plant material derived from field-grown plants exhibiting phenotypic variability in susceptibility to agave wilt. The offshoots from rhizomes of these plants were reproduced in vitro and classified as potentially resistant or susceptible. Amplified fragment length polymorphism analysis confirmed wide genetic differences among individuals, but these differences were not correlated with the observed phenotypic variability in resistance. Propagated plantlets were inoculated with Fusarium solani in two time-lapse confrontations for 72 h and 30 days. The early biochemical response showed statistically superior levels in the accumulation of shikimic acid, phenolic compounds, and chitinase activity in potentially resistant plantlets. There was an inverse correlation of these early biochemical responses and salicylic acid and the incidence of diseased root cells in isogenic plantlets in the 30-day confrontation with F. solani, suggesting that these activities and accumulation of molecules were primordial in the defence against this pathogen.

Insects associated with the genus Agave spp. (Asparagaceae) in Mexico.

We present a synthesis of the insects reported associated with plants of the genus Agave L. (Asparagaceae) in Mexico, through a detailed review of published records. This work includes two checklists: the first include the species of insects collected in Agave, name of their hosts, their geographical distribution, notes on their biology and, references. Natural enemies of the insects associated with agaves are included in the second checklist with their geographical distribution, insect species host and, references. We found 273 species of insects collected in different Agave species. These species belong to 63 families and 7 orders. The orders of insects with the highest number of species are Coleoptera with 118 species and, Hemiptera with 65. The natural enemies of insects collected in agaves were 98 species from 18 families and 6 orders. The genera Aphytis and Encarsia (Hymenoptera: Aphelinidae) grouped the largest number of natural enemies of insects that were recorded in Agave with 15 and 10 species, respectively. Insects were collected from 42 species of Agave, of which 25 are endemic to Mexico. This study provides biological information on Mexican insects captured in Agave and, their natural enemies. The need for the conservation of these plants and associated insects is highlighted.