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Lycoris longituba is an important ornamental and medicinal plant and contains various Amaryllidaceae alkaloids such as galanthamine (GAL), lycorine (LYC), and lycoramine (LYCM), which have been reported to exhibit medicinal values. However, the effects of light quality on L. longituba are unknown. The present study aimed to explore the effects of different light emitting diode (LED) light quality on growth, physiological characteristics, and alkaloid accumulations in the seedlings. Lycoris longituba seedlings were cultured under different ratios of blue and red LEDs. The results showed that compared to CK, RB (1:2) treatment improved growth, biomass accumulation, and the synthesis of photosynthetic pigments and reduced membrane lipid peroxidation. Blue light increased GAL, LYC, and LYCM contents which were 2.45-, 1.74-, and 1.92-fold higher than CK, respectively. Most of Amaryllidaceae alkaloids biosynthetic pathway genes including PAL, C4H, NBS, TYDC, OMT, and CYP96T1 were upregulated under B treatment. In general, RB (1:2) was the optimal light quality condition for the growth of L. longituba seedlings. B treatment could promote the accumulation of alkaloids and related gene expressions. This study has established the theoretical foundation and technical support for the use of LED light quality control technology in the production of high-quality L. longituba seedlings. [ABSTRACT FROM AUTHOR]

Key message: Nitrogen availability and cytokinin could promote shoot branching in rice, whereas auxin and strigolactone inhibited it. The interaction between nitrogen availability and the three hormones is discussed. Abstract: Rice shoot branching is strongly affected by nitrogen availability and the plant hormones auxin, cytokinin, and strigolactone; however, the interaction of them in the regulation of rice shoot branching remains a subject of debate. In the present study, nitrogen and the three hormones were used to regulate rice tiller bud growth in the indica rice variety Yangdao 6. Both nitrogen and CK promoted shoot branching in rice, whereas auxin and SL inhibited it. We used HPLC to determine the amounts of endogenous IAA and CK, and we used quantitative real-time PCR analysis to quantify the expression levels of several genes. Nitrogen enhanced the amount of CK by promoting the expression levels of OsIPTs in nodes. In addition, both nitrogen and CK downregulated the expression of genes related to SL synthesis in root and nodes, implying that the inhibition of SL synthesis by nitrogen may occur at least partially through the CK pathway. SL did not significantly reduce the amount of CK or the expression levels of OsIPT genes, but it did significantly reduce the amount of auxin and the auxin transport capacity in nodes. Auxin itself inhibited CK synthesis and promoted SL synthesis in nodes rather than in roots. Furthermore, we found that CK and SL quickly reduced and increased the expression of FC1 in buds, respectively, implying that FC1 might be a common target for the CK and SL pathways. Nitrogen and auxin delayed expression change patterns of FC1, potentially by changing the downstream signals for CK and SL. [ABSTRACT FROM AUTHOR]

Apical dominance refers to the inhibition of shoot branching by the dominant shoot apex. The underlying mechanisms of apical dominance, especially in rice ( Oryza sativa), remain a subject of debate. Here, we studied apical dominance in the indica rice variety 'Yangdao 6' and carried out a comparative proteomic analysis to analyze the different levels of expression of proteins after decapitation. A total of 38 differentially expressed proteins in nodes and buds were successfully identified by MALDI-TOF/TOF and these proteins comprised ten functional categories. Among them, several proteins in this study involved in signal transduction, transporters, and cytokinin biosynthesis may play an important role in the mechanism of apical dominance. In addition, qRT-PCR was used to quantitate the expression levels of several genes in rice nodes and buds. The results showed that after decapitation, the expression level of a CK synthesis gene, OsLOG7, was reduced in buds, however, expression levels of several CK synthesis genes, OsIPTs, were markedly increased in nodes, indicating that after panicle removal, cytokinins were synthesized in nodes and subsequently delivered to buds, which will trigger release from dormancy in buds. Expression levels of several strigolactone-related genes were reduced in nodes after decapitation, which may become a factor facilitating auxin transport out of buds to stems. [ABSTRACT FROM AUTHOR]

Key message: Sixty-three proteins were identified to be differentially accumulated due to iron deficiency in shoot and root. The importance of these proteins alterations on shoot physiology is discussed. Abstract: Iron (Fe) is an essential micronutrient for plant growth and its accumulation affects the quality of edible plant organs. To investigate the adaptive mechanism of a Chinese rice variety grown under iron deficiency, proteins differentially accumulated in leaves and roots of Yangdao 6, an indica cultivar, under Fe deficiency growth condition, were profiled using a two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS). The accumulations of seventy-three proteins were detected to be increased or decreased upon iron deficiency, and sixty-three of them were successfully identified. Among the sixty-three proteins, a total of forty proteins were identified in rice leaves, and twenty-three proteins were in roots. Most of these proteins are involved in photosynthesis, C metabolism, oxidative stress, Adenosine triphosphate synthesis, cell growth or signal transduction. The results provide a comprehensive way to understand, at the level of proteins, the adaptive mechanism used by rice shoots and roots under iron deficiency. [ABSTRACT FROM AUTHOR]

Hormones play an important role in regulating the growth of rice tiller buds. However, little is known about the hormonal changes that occur during tiller bud growth and the mechanism of hormonal regulation of tiller bud growth. Here, two rice cultivars, Yangdao 6 (Indica) and Nanjing 44 (Japonica), were used to investigate the changes in plant hormones during tiller bud growth and the mechanism that underlies the hormonal regulation of tiller bud growth. In the present study, panicles were removed after heading to stimulate the growth of dormant tiller buds located at the elongated upper internodes. At the same time, external abscisic acid (ABA), gibberellic acid (GA) and α-naphthalene acetic acid (NAA) were applied. The results demonstrated that auxin and cytokinin (CTK) play important and different roles in the regulation of tiller bud growth. Auxin in the nodes inhibits tiller bud growth, while CTK is transferred to the tiller buds to promote growth. The inhibitory effects of GA and NAA on tiller bud growth are mainly due to the control of the indole-3-acetic acid (IAA) or CTK contents in plants. As opposed to auxin and CTK, the ABA contents in nodes and tiller buds remained unchanged before tiller bud growth after panicle removal. Meanwhile, external ABA application only slightly slowed the growth of the tiller buds, suggesting that ABA may not be a key regulator of tiller bud growth. These results indicate that auxin, CTK and ABA together likely play roles in the regulation of tiller bud growth. [ABSTRACT FROM AUTHOR]