Inequality Measure of Leaf Area Distribution for a Drought-Tolerant Landscape Plant

Measuring the inequality of leaf area distribution per plant (ILAD) can provide a useful tool for quantifying the influences of intra- and interspecific competition, foraging behavior of herbivores, and environmental stress on plants' above-ground architectural structures and survival strategies. Despite its importance, there has been limited research on this issue. This paper aims to fill this gap by comparing four inequality indices to measure ILAD, using indices for quantifying household income that are commonly used in economics, including the Gini index (which is based on the Lorenz curve), the coefficient of variation, the Theil index, and the mean log deviation index. We measured the area of all leaves for 240 individual plants of the species Shibataea chinensis Nakai, a drought-tolerant landscape plant found in southern China. A three-parameter performance equation was fitted to observations of the cumulative proportion of leaf area vs. the cumulative proportion of leaves per plant to calculate the Gini index for each individual specimen of S. chinensis. The performance equation was demonstrated to be valid in describing the rotated and right shifted Lorenz curve, given that >96% of root-mean-square error values were smaller than 0.004 for 240 individual plants. By examining the correlation between any of the six possible pairs of indices among the Gini index, the coefficient of variation, the Theil index, and the mean log deviation index, the data show that these indices are closely related and can be used interchangeably to quantify ILAD.

Plant growth and heavy meal accumulation characteristics of Spathiphyllum kochii cultured in three soil extractions with and without silicate supplementation

A hydroponic method was conducted to test whether Spathiphyllum kochii is tolerant to multiple HMs as well as to evaluate whether sodium silicate promotes plant growth and alleviates HM stress mainly by assessing biomass, HM accumulation characteristics and antioxidant enzyme activities (AEAs). Three soil extractions from an uncontaminated soil, a comparable lightly HM-contaminated soil (EnSE), and a comparable heavily HM-contaminated soil (ExSE) with or without 1 mM sodium silicate supplementation were used. S. kochii showed no obvious symptoms when cultured in EnSE and ExSE, indicating that it was a multi-HM-tolerant species. The biomass and photosynthesis followed the order: UnSE > EnSE > ExSE, but the opposite order was found for HM concentration, AEAs, and malondialdehyde content. Silicate had no effects on the growth and HM bioaccumulation characteristics of S. kochii cultured in UnSE but exhibited a novel role in decreasing HM uptake by 13.61-41.51% in EnSE and ExSE, respectively, corresponding upregulated AEAs, and reduced malondialdehyde contents, resulting in increased biomass and alleviating HM stress. The activities of peroxidase and superoxide dismutase were upregulated by an increase in soil extraction HM concentration and further upregulated by silicate supplementation, indicating that they were important mechanisms alleviating HM stress in S. kochii.

The complete chloroplast genome sequence of endangered plant Trachycarpus nanus (Arecaceae)

Trachycarpus nanus is an endangered plant that is endemic to southwest of China. In the present study, the complete chloroplast genome of this species was assembled and characterized using whole genome next-generation sequencing. The complete chloroplast genome showed a circular genome of 158,713 bp size with 36.6% GC content. The genome is of typical structure and contain a pair of inverted repeat (IR) regions with 27,240 bp, separated by one large single-copy (LSC) with 86,395 bp, and one small single-copy (SSC) regions with 17,838 bp. The genome contained 132 genes, including 86 protein-coding genes, 8 rRNA genes and 38 tRNA genes. A phylogenetic tree reconstructed based on 21 chloroplast genomes reveals that Trachycarpus nanus is most related with Chamaerops humilis. The information provides important genetic basis for the species’ future studies on phylogenetic and utilization.

The complete chloroplast genome of Laurocerasus zippeliana (Rosaceae)

Laurocerasus zippeliana is a widely known landscape plant with high adaptability. We report herein the complete chloroplast genome sequence of L. zippeliana assembled from Illumina high-throughput sequencing data. With a total length of 158,940 bp, the complete chloroplast genome was a typical quadripartite circle: two inverted repeats (IRs) of 26,339 bp for each, a large single-copy (LSC) region of 87,339 bp, and a small single-copy (SSC) region of 18,923 bp. A total of 110 unique genes were identified, consisting of 78 protein-coding genes, 28 tRNA genes, and 4 rRNA genes. Phylogenetic analysis confirmed the position of L. zippeliana within the order Rosales.