Preliminary assessment of seed heteromorphism as an adaptive strategy of Colobanthus quitensis under saline conditions

Colobanthus quitensis is known for enduring extreme conditions, such as high salinity in Antarctica, making it an excellent model for studying environmental stress. In plant families, variations in seed color heteromorphism have been linked to various germination under stress conditions. Preliminary laboratory observations indicated that dark brown seeds of C. quitensis had higher germination rates, suggesting that this phenotypic trait might offer a germination advantage, particularly under saline conditions. To investigate this, germination of heteromorphic seeds from Antarctic, sub-Antarctic, and Andean populations of C. quitensis was assessed under in vitro saline conditions. Among all populations, dark brown seeds exhibited greater germination and shorter germination time than other seeds in the absence of salinity. In the Antarctic population, dark brown seeds showed better salinity tolerance. In the sub-Antarctic La Marisma population, salt tolerance was not affect by seed color, showing the population was the most salt-tolerant. The other two populations showed very low germination even at low salinity concentration. This study is the first scientific report of seed heteromorphism in C. quitensis populations, offering insights into mechanisms of salinity tolerance and potentially other stress conditions that enhance the species' resilience. In addition, the identification of La Marisma populations as a salinity-tolerant population will holds biotechnological importance for agriculture.