Yulong Ding

Comparison of dwarf bamboos (Indocalamus sp.) leaf parameters to determine relationship between spatial density of plants and total leaf area per plant

Abstract The relationship between spatial density and size of plants is an important topic in plant ecology. The self‐thinning rule suggests a −3/2 power between average biomass and density or a −1/2 power between stand yield and density. However, the self‐thinning rule based on total leaf area per plant and density of plants has been neglected presumably because of the lack of a method that can accurately estimate the total leaf area per plant. We aimed to find the relationship between spatial density of plants and total leaf area per plant. We also attempted to provide a novel model for accurately describing the leaf shape of bamboos. We proposed a simplified Gielis equation with only two parameters to describe the leaf shape of bamboos one model parameter represented the overall ratio of leaf width to leaf length. Using this method, we compared some leaf parameters (leaf shape, number of leaves per plant, ratio of total leaf weight to aboveground weight per plant, and total leaf area per plant) of four bamboo species of genus Indocalamus Nakai (I. pedalis (Keng) P.C. Keng, I. pumilus Q.H. Dai and C.F. Keng, I. barbatus McClure, and I. victorialis P.C. Keng). We also explored the possible correlation between spatial density and total leaf area per plant using log‐linear regression. We found that the simplified Gielis equation fit the leaf shape of four bamboo species very well. Although all these four species belonged to the same genus, there were still significant differences in leaf shape. Significant differences also existed in leaf area per plant, ratio of leaf weight to aboveground weight per plant, and leaf length. In addition, we found that the total leaf area per plant decreased with increased spatial density. Therefore, we directly demonstrated the self‐thinning rule to improve light interception.

Exploring key cellular processes and candidate genes regulating the primary thickening growth of Moso underground shoots.

The primary thickening growth of Moso (Phyllostachys edulis) underground shoots largely determines the culm circumference. However, its developmental mechanisms remain largely unknown. Using an integrated anatomy, mathematics and genomics approach, we systematically studied cellular and molecular mechanisms underlying the growth of Moso underground shoots. We discovered that the growth displayed a spiral pattern and pith played an important role in promoting the primary thickening process of Moso underground shoots and driving the evolution of culms with different sizes among different bamboo species. Different with model plants, the shoot apical meristem (SAM) of Moso is composed of six layers of cells. Comparative transcriptome analysis identified a large number of genes related to the vascular tissue formation that were significantly upregulated in a thick wall variant with narrow pith cavity, mildly spiral growth, and flat and enlarged SAM, including those related to plant hormones and those involved in cell wall development. These results provide a systematic perspective on the primary thickening growth of Moso underground shoots, and support a plausible mechanism resulting in the narrow pith cavity, weak spiral growth but increased vascular bundle of the thick wall Moso.

A geometrical model for testing bilateral symmetry of bamboo leaf with a simplified Gielis equation

Abstract The size and shape of plant leaves change with growth, and an accurate description of leaf shape is crucial for describing plant morphogenesis and development. Bilateral symmetry, which has been widely observed but poorly examined, occurs in both dicot and monocot leaves, including all nominated bamboo species (approximately 1,300 species), of which at least 500 are found in China. Although there are apparent differences in leaf size among bamboo species due to genetic and environmental profiles, bamboo leaves have bilateral symmetry with parallel venation and appear similar across species. Here, we investigate whether the shape of bamboo leaves can be accurately described by a simplified Gielis equation, which consists of only two parameters (leaf length and shape) and produces a perfect bilateral shape. To test the applicability of this equation and the occurrence of bilateral symmetry, we first measured the leaf length of 42 bamboo species, examining >500 leaves per species. We then scanned 30 leaves per species that had approximately the same length as the median leaf length for that species. The leaf‐shape data from scanned profiles were fitted to the simplified Gielis equation. Results confirmed that the equation fits the leaf‐shape data extremely well, with the coefficients of determination being 0.995 on average. We further demonstrated the bilateral symmetry of bamboo leaves, with a clearly defined leaf‐shape parameter of all 42 bamboo species investigated ranging from 0.02 to 0.1. This results in a simple and reliable tool for precise determination of bamboo species, with applications in forestry, ecology, and taxonomy.

Internode morphometrics and allometry of Tonkin Cane Pseudosasa amabilis

Abstract Pseudosasa amabilis (McClure) (Poales: Gramineae) is a typical bamboo species naturally distributed in large area of south China and famous for its culm strength. Although bamboos were found to share the same development rule, the detailed internode morphology of bamboo culm was actually not fully expressed. We explored internode morphology of P. amabilis using 11 different physical parameters in different dimensions (1–4). As Taylors power law (TPL) is generally applicable to describe relationship between mean and variance of population density, here we used TPL to evaluate the differences between internodes, and further, the relationship between dimension and TPL. Results showed that length (L), hollow radius (HR), hollow area (HA), hollow cylinder volume (HCV), total cylinder volume (TCV), density (De), and weight (W) all presented positive skewed distribution in varying degrees. For the basic one‐dimensional parameters, the 9th internode was the longest, the 7th the heaviest, while thickness (T) decreased with internodes. Diameter (D) decreased in general but with an inconspicuous local mode at the 5–6th internodes, potentially due to the rapid height growth. The longest (9th) internode was the “turning point” for T‐D and HR‐D relationships. Scatter plot changing trends of W to the one‐dimensional parameters after the heaviest (7th) internode were reversed, indicating a deceleration of growth speed. TPL was not holding well in one‐dimensional parameters (R 2: 0.5413–0.8125), but keep increasing as the parameters dimension increasing (R 2 > 0.92 for two‐dimensional, R 2 > 0.97 for three‐dimensional, and R 2 > 0.99 for four‐dimensional parameters.), suggesting an emergence mechanism of TPL related to both the physical dimensions of morphological measures and the allometric growth of bamboo. From the physical fundamental level, all existences are the expression of energy distribution in different dimensions, implying a more general rule that energy distribution holds better TPL in higher dimension level.

Synthetic promoters consisting of defined cis-acting elements link multiple signaling pathways to probenazole-inducible system

Probenazole (3-allyloxy-1,2-benzisothiazole-1,1-dioxide, PBZ), the active component of Oryzemate, could induce systemic acquired resistance (SAR) in plants through the induction of salicylic acid (SA) biosynthesis. As a widely used chemical inducer, PBZ is a good prospect for establishing a new chemical-inducible system. We first designed artificially synthetic promoters with tandem copies of a single type of cis-element (SARE, JERE, GCC, GST1, HSRE, and W-box) that could mediate the expression of the β-glucuronidase (GUS) reporter gene in plants upon PBZ treatment. Then we combined different types of elements in order to improve inducibility in the PBZ-inducible system. On the other hand, we were surprised to find that the cis-elements, which are responsive to jasmonic acid (JA) and ethylene, also responded to PBZ, implying that SA, JA, and ethylene pathways also would play important roles in PBZ’s action. Further analysis demonstrated that PBZ also induced early events of innate immunity via a signaling pathway in which Ca2+ influx and mitogen-activated protein kinase (MAPK) activity were involved. We constructed synthesized artificial promoters to establish a PBZ chemical-inducible system, and preliminarily explored SA, JA, ethylene, calcium, and MAPK signaling pathways via PBZ-inducible system, which could provide an insight for in-depth study.摘要目的构建有效响应烯丙异噻唑 (PBZ) 诱导的人工合成启动子, 了解植物体内受PBZ诱导系统触发的信号途径。创新点通过分析包含已知顺式元件的人工合成启动子对PBZ 的响应性, 为构建一种基于PBZ诱导系统的新型化学诱导启动子提供了可能性, 并初步揭示了除水杨酸 (SA) 外, 茉莉酸 (JA) 和乙烯等多条信号途径可能共同参与了PBZ诱导的植物免疫反应过程。方法利用已知的响应相关信号通路的顺式作用元件构建人工合成启动子, 融合GUS报告基因后, 稳定转化拟南芥。通过检测PBZ处理过程中GUS酶活性的变化, 了解人工合成启动子对PBZ 的响应性, 分析PBZ诱导系统可能触发的信号途径。结论除了SA响应元件SARE 可以有效响应PBZ诱导外, 利用JA和乙烯响应元件JERE和GCC, 超敏反应 (HR) 相关的顺式元件HSRE和GST1, 以及植物抗病反应中重要顺式作用元件W-box构建的人工合成启动子也均可有效响应PBZ。另外, 通过人工合成启动子响应性分析的手段, 初步揭示了包括SA、JA、乙烯、钙离子和丝裂原活化蛋白激酶 (MAPKs) 在内的多条信号通路可能共同参与了PBZ诱导植物免疫反应的过程。

Why Does Not the Leaf Weight-Area Allometry of Bamboos Follow the 3/2-Power Law?

The principle of similarity (Thompson, 1917) states that the weight of an organism follows the 3/2-power law of its surface area and is proportional to its volume on the condition that the density is constant. However, the allometric relationship between leaf weight and leaf area has been reported to greatly deviate from the 3/2-power law, with the irregularity of leaf density largely ignored for explaining this deviation. Here, we choose 11 bamboo species to explore the allometric relationships among leaf area (A), density (ρ), length (L), thickness (T), and weight (W). Because the edge of a bamboo leaf follows a simplified two-parameter Gielis equation, we could show that A ∝ L2 and that A ∝ T2. This then allowed us to derive the density-thickness allometry ρ ∝ Tb and the weight-area allometry W ∝ A(b+3)/2 ≈ A9/8, where b approximates −3/4. Leaf density is strikingly negatively associated with leaf thickness, and it is this inverse relationship that results in the weight-area allometry to deviate from the 3/2-power law. In conclusion, although plants are prone to invest less dry mass and thus produce thinner leaves when the leaf area is sufficient for photosynthesis, such leaf thinning needs to be accompanied with elevated density to ensure structural stability. The findings provide the insights on the evolutionary clue about the biomass investment and output of photosynthetic organs of plants. Because of the importance of leaves, plants could have enhanced the ratio of dry material per unit area of leaf in order to increase the efficiency of photosynthesis, relative the other parts of plants. Although the conclusion is drawn only based on 11 bamboo species, it should also be applicable to the other plants, especially considering previous works on the exponent of the weight-area relationship being less than 3/2 in plants.

Studies on Development of Megasporogenesis and Female Gametophyte of Bambusa multiplex

In order to discuss whether the development of the female organ is normal, the development of megasporogenesis and female gametophyte of Bambusa multiplex was studied by the method of traditional paraffin section and SEM. The results showed that the ovary had one anatropous ovule, bitegmic and tenuinucellate. A female archesporial cell developed into megaspore mother cell directly, linear tetrad. The functional megaspore near the micropyle developed into mature embryo sac with eight nucleuses in 7 cells, including 3 antipodal cells arranged transversely near the chalazal and egg apparatus (1 egg cell and 2 synergid cells) near the micropylar end and a central cell (2 polar nucleus). In addition, the corresponding development relationship between pistil and stamen was established, which discovered the anthers and stigmas of B. multiplex matured at the same time. The corresponding development relationship between pistil and stamen may provide the reference for the developmental phase of embryo sac according to the anther length. During the pistil development process abnormal structures of ovaries may be one of the reasons of the low seed rate.

Erratum to: Synthetic promoters consisting of defined cis

Zheng ZHU, Jiong GAO, Jin-xiao YANG, Xiao-yan WANG, Guo-dong REN, Yu-long DING, Ben-ke KUAI (The Southern Modern Forestry Collaborative Innovation Center, Nanjing Forestry University, Nanjing 210037, China) (State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200438, China) (College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China) (Bamboo Research Institute, Nanjing Forestry University, Nanjing 210037, China) E-mail: bkkuai@fudan.edu.cn

Molecular cloning and characterization of a chlorophyll degradation regulatory gene from bamboo

Leaf senescence constituted the final stage of leaf development and it is always accompanied by the leaf yellowing. The non-yellowing gene (NYE1), initially identified from Arabidopsis in our laboratory, is a key regulatory gene responsible for chlorophyll degradation during senescence. In this study, an orthologue of AtNYE1 was isolated from the bamboo (Bambusa emeiensis cv. Viridiflavus) and tentatively named BeNYE1. The full length sequence of 1 386 bp contains an open reading frame of 801 bp. The protein encoded by BeNYE1 consists of 266 amino acids. Sequence analysis revealed that BeNYE1 had high similarity with other NYE/SGR proteins from various monocotyledon species. BeNYE1 was strongly induced by natural senescence and dark-induced senescence in bamboo. Driven by a 1.5 kb upstream fragment of AtNYE1, BeNYE1 could rescue the stay-green phenotype of nye1-1. The constitutive over-expression of BeNYE1 could accelerate the chlorophyll degradation. These results indicated that BeNYE1 might play an important role in the regulation of chlorophyll degradation during leaf senescence in bamboo.