Abstract
Plant growth and development are tightly regulated by phytohormones. However, little is known about the interaction between auxin and gibberellin acid (GA) during flower stalk elongation and how it is directly related to organ formation. Therefore, the effects of indole acetic acid (IAA) and GA3 treatments and their interaction on flower stalk elongation in flowering Chinese cabbage were investigated. The growth of flowering Chinese cabbage is regulated by IAA and GA3, and the opposite results were observed after treatments with uniconazole (GA synthesis inhibitor) and N-1-naphthylphthalamic acid (NPA) (auxin transport inhibitor). Anatomical analysis of the pith region in stalks revealed that IAA promoted expansion via signal transduction and transport pathways. GA3 regulated the elongation of flower stalks by controlling GA synthesis and partially controlling the IAA signaling pathway. GA3 also had a stronger effect on stalk elongation than IAA. The results of qRT-PCR and histological analysis revealed that GA3 and IAA induced the expansion of cell walls by activating the expression of genes encoding cell wall structural proteins such as Expansin (EXP). These findings provide new insights into the mechanism of stalk formation regulated by the combination of IAA and GA3.
Highlights
Plant growth and development are tightly regulated by phytohormones
The stalk elongation of flowering Chinese cabbage was significantly inhibited by decapitation and N-1naphthylphthalamic acid (NPA) (N-1-naphthylphthalamic acid) treatments, whereas stalk elongation was stimulated by indole acetic acid (IAA) treatment (Fig. 1a)
Endogenous IAA and gibberellin acid (GA) contents were significantly reduced in the intact plants + NPA treatment group compared to those in intact plants
Summary
Plant growth and development are tightly regulated by phytohormones. little is known about the interaction between auxin and gibberellin acid (GA) during flower stalk elongation and how it is directly related to organ formation. The growth of flowering Chinese cabbage is regulated by IAA and GA3, and the opposite results were observed after treatments with uniconazole (GA synthesis inhibitor) and N-1naphthylphthalamic acid (NPA) (auxin transport inhibitor). The results of qRT-PCR and histological analysis revealed that GA3 and IAA induced the expansion of cell walls by activating the expression of genes encoding cell wall structural proteins such as Expansin (EXP) These findings provide new insights into the mechanism of stalk formation regulated by the combination of IAA and GA3. Among these, flowering Chinese cabbage (B. campestris), Chinese kale (B. alboglabra), and purple cai-tai (B. campestris) are usually named cruciferous stalk vegetables because their edible parts are their elongated and expanded flower stalks ( called flower stems) These flower stalks are part of the major reproductive organs, which determine the yield and nutritional q uality[3]. The regulation mechanism between the formation of the swelled stalk and IAA supplemented with GA were carefully investigated in the present study
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