The ‘paradox of sex’ refers to the puzzle of why the sexual mode of reproduction is more common among living beings than the asexual mode.
Sexual reproduction requires at least two mates, exposes individuals to a higher risk of diseases, and is more energy intensive. In contrast, asexual reproduction makes up for all of these disadvantages by requiring only one parent while allowing for the rapid generation of offspring. Now, this ‘paradox’ has been bolstered by findings from a new study regarding a species of pathogenic fungi that infects a variety of cultivates grains, such as rice, wheat, barley, and finger millet.
Pyricularia (Magnaporthe) oryzae, a species of pathogenic filamentous fungi, wreaks havoc on global rice production as it causes the rice blast disease, which has earned it the moniker ’rice blast fungus’. The infection cycle begins with asexual reproduction, where asexual spores called ‘conidia’ attach to the surface of the leaves of the rice plant.
This produces an infection-specific structure called an appressorium, which starts to penetrate the outermost cell layer of the leaf, resulting in visible lesions on the leaf surface. When conditions are favorable, specialized structures called conidiophores emerge and produce more conidia, which disperse through the wind or atmospheric droplets to more rice plants.
While this asexual mode of reproduction is the main driving force of the P. oryzae life cycle, scientists have demonstrated the successful sexual reproduction of this fungus in laboratory settings. The fungus appears to have strains equivalent to biological males and biological females. However, most specimens collected from the fields show a loss of female fertility. The underlying genes and mechanisms responsible for the loss of sexual reproduction in P. oryzae have remained a mystery.
2023-07-24 18:48:03
Original from phys.org