Changes of starch and sucrose content and related gene expression during the growth and development of Lanzhou lily bulb

As the main forms of carbohydrates, starch and sucrose play a vital role in the balance and coordination of various carbohydrates. Lanzhou lily is the most popular edible lily in China, mainly distributed in the central region of Gansu. To clarify the relationship between carbohydrate metabolism and bulb development of Lanzhou lily, so as to provide a basis for the promotion of the growth and development in Lanzhou lily and its important economic value, we studied lily bulbs in the squaring stage, flowering stage, half withering stage and withering stage. The plant height, fresh weight of mother and daughter bulbs continued to increase during the whole growth period and fresh weight of stem and leaf began to decrease in the half withering stage. The content of starch, sucrose and total soluble sugar in the lily mother bulb accumulated mostly in the flowering, withering and half withering stages, respectively. Starch, sucrose and total soluble sugar accumulated in the daughter bulb with the highest concentration during the withering stage. In the transcription level, sucrose synthase (SuSy1) and sucrose invertase (INV2) expressed the highest in squaring stage, and the expression was significantly higher in the mother bulb than in the daughter bulb. In flowering stage, the expression levels of soluble starch synthase (SSS1), starch-branching enzyme (SBE) and adenosine diphosphate-glucose pyrophosphorylase (AGP1) genes were higher in the mother bulb than in the daughter bulb. Altogether, our results indicate that starch and sucrose are important for the bulb growth and development of Lanzhou lily.

Characteristics of Cuticular Wax and Analysis of Wax Biosynthesis Related Genes in Lanzhou Lily(Lilium Davidii Var. Unicolor) Under Drought Stress

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The Antioxidant Defense System during Lanzhou Lily Scales Storage Is Modulated by Hydrogen Sulfide

As an important gaseous regulator, hydrogen sulfide (H2S) is involved in various aspects of plant processes, including seed germination, stomatal movement, and postharvest senescence. The preservation capacity of Lanzhou lily (Lilium davidii var. unicolor Salisb) scales fumigated with or without exogenously applied sodium hydrosulfide (NaHS, a H2S donor) was investigated in the current study. Results indicate that NaHS fumigation was able to extend storage life and elicit endogenous H2S production of postharvest Lanzhou lily scales with an optimal concentration at 0.8 mM. Moreover, exogenously applied NaHS (0.8 mM) led to higher soluble sugar, soluble protein, and ascorbic acid levels and lower total phenolic and flavonoid contents compared with those of the control. The application of 0.8 mM NaHS also reduced the lipid peroxidation level and reactive oxygen species (ROS) accumulation in scales, as indicated by the lower malondialdehyde (MDA) content, relative conductivity, lipoxygenase (LOX) activity, O2− production rate, and hydrogen per-oxide (H2O2) content. Further, scales treated with 0.8 mM NaHS exhibited significantly higher activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbic acid peroxidase (APX). Collectively, our data provide new insight into how the postharvest senescence of Lanzhou lily scales might be alleviated by H2S by enhancing antioxidant defense systems.

Autotoxic compounds from rhizosphere soil of lanzhou lily extracts: Identification and biological activity

We investigated the autotoxicity of Lanzhou lily rhizosphere soil with different cultivation years. The allelochemicals in such soils were isolated and identified by gas chromatography-mass spectrometry (GC-MS). Based on our earlier studies, the antioxidant 2246 and dioctyl terephthalate were found in lily sick soil were used in pot experiments determine to their autotoxic effects on the Lanzhou lily seedlings growth, photosynthetic parameters and antioxidant enzyme activities in seedling leaves. The content of antioxidant 2246 and dioctyl terephthalate was determined by GC-MS in rhizosphere soil of different cultivation years. The aqueous extracts of Lanzhou lily rhizosphere soil promoted the growth of its own seedlings at 0.2 mg·mL-1, however, the concentrations > 2 mg·mL-1 were inhibitory. The longer the cultivation period (1-yr, 2-yr and 4-yr), the stronger were the inhibitory effects. In rhizosphere soils of 1-yr, 2-yr and 4-yr ; 8,: 15 and 18 compounds were identified, respectively. The identified compounds were camphor, 3-hydroxy-4-methoxy-benzaldehyde, 2,4-bis(1,1- dimethylethyl)-phenol, tributyl phosphate, dibutyl phthalate, antioxidant 2246 and dioctyl terephthalater and these are reported as allelochemicals. The pot experiment results showed that low concentrations of antioxidant 2246 stimulated the seedling growth but high concentrations were inhibitory, while all concentrations of dioctyl terephthalater inhibited the seedling growth. At 100 mg·mL-1, the antioxidant 2246 and dioctyl terephthalate significantly inhibited the photosynthesis and antioxidant enzyme activity in leaves (P <0.05). Furthermore, the content of these two compounds in soils increased with the increase of cultivation years. These results suggested that allelochemicals accumulated in replanted soil contributed to the autotoxicity of Lanzhou lily in rhizosphere soil.