Ex-situ cultivation of Isoetes cangae and Isoetes serracarajensis (Isoetaceae) two endemic species from Brazilian Amazon

Isoetes L. is a genus of lycophytes widely distributed around the world that has a large number of endemic species. Here we document the first successful large scale ex-situ cultivation of the new endemic species from Brazilian Amazon quillworts Isoetes cangae and Isoetes serracarajensis. These isoetids are endemic of an iron mining site and grow on a superficial iron crust that occurs over ferriferous rocks. This study aimed to develop the cultivation methods of the threatened species I. cangae and monitoring its unique physiology. Plants from both species brought from Amazon lagoons were cultivated through a year in a low-cost system at a different site during different seasons. The survival rate of plants was higher as 98% and both species developed well under cultivation but showed different patterns during linear growth: I. cangae showed faster leaf development but was slower on sprout production than I. serracarajensis. The mechanism of leaf expansion is related to plasma membrane H+-ATPase activation, near to 2-fold higher in I. cangae. On the other hand, the effective quantum yield of photosystem II was higher in I. serracarajensis than in I. cangae. During the cultivation, new sporophytes of I. cangae were produced, confirming its reproductive status. We have also tested elevated iron levels on the growth of plants, but no interference of iron concentration was observed. The results of this work have broad applicability, assisting other low-cost cultivation studies, which are very important in ecosystem recovery of mining areas and conservation strategies.