Relationships between strigolactone production and shoot branching in rice under nutrient deficiency

Abstract

Strigolactones were previously found in root exudates acting as communication chemicals with root parasitic weeds and symbiotic arbuscular mycorrhizal (AM) fungi. Recently, we have found that strigolactones also inhibit shoot branching in the host plants. However, it is still unclear why strigolactones act as inhibitors of shoot branching as well as being chemical signals in the rhizosphere. Strigolactone production is known to increase under phosphorus deficiency. This is thought to be a strategy of plants to activate AM fungi, which facilitate the uptake of soil nutrients by host plants. On the other hand, plants need to minimize shoot branching under nutrient deficiency for efficient utilization of the nutrient. To study the possible role of strigolactones in regulating shoot branching in response to nutrient deficiency, we investigated the relationships between strigolactone production and shoot branching under varying nutrient conditions using wild type and strigolactone-deficient mutants of rice.