AUTHOR=Elizarraraz-Martínez Iris J. , Rojas-Raya Mariana A. , Feregrino-Pérez Ana A. , Partida-Martínez Laila P. , Heil Martin 

TITLE=Immunity priming and biostimulation by airborne nonanal increase yield of field-grown common bean plants

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1451864

DOI=10.3389/fpls.2024.1451864

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Stress-induced volatile organic compounds (VOCs) that induce plant immunity bear potential for biocontrol. Here, we explore the potential of nonanal to enhance the seed yield of common bean (<italic>Phaseolus vulgaris</italic>) under open field conditions that are realistic for smallholder farmers.</p></sec><sec><title>Methods and results</title><p>Using plastic cups with a nonanal-containing lanolin paste as low-cost dispensers, we observed that exposure of Flor de Junio Marcela (FJM) plants over 48h to airborne nonanal was followed by a 3-fold higher expression of pathogenesis-related (PR) genes PR1 and PR4. Both genes further increased their expression in response to subsequent challenge with the fungal pathogen <italic>Colletotrichum lindemuthianum</italic>. Therefore, we conclude that nonanal causes resistance gene priming. This effect was associated with ca. 2.5-fold lower infection rates and a 2-fold higher seed yield. Offspring of nonanal-exposed FJM plants exhibited a 10% higher emergence rate and a priming of PR1- and PR4-expression, which was associated with decreased infection by <italic>C. lindemuthianum</italic> and, ultimately, a ca. 3-fold increase in seed yield by anthracnose-infected offspring of nonanal-exposed plants. Seeds of nonanal-exposed and of challenged plants contained significantly more phenolic compounds (increase by ca 40%) and increased antioxidant and radical scavenging activity. Comparative studies including five widely used bean cultivars revealed 2-fold to 3-fold higher seed yield for nonanal-exposed plants. Finally, a cost-benefit analysis indicated a potential economic net profit of nonanal exposure for some, but not all cultivars.</p></sec><sec><title>Outlook</title><p>We consider nonanal as a promising candidate for an affordable tool that allows low-income smallholder farmers to increase the yield of an important staple-crop without using pesticides</p></sec>