Search

Background Isoetes yunguiensis Q. F. Wang & W. C. Taylor is a lycophyte of an ancient genus, and it is endemic to China. It is a first-class protected plant in China. This living fossil is used in paleoecology and studies on the evolution of Lycophytes in the Yunnan-Guizhou Plateau. In recent years, human activities have caused the disappearance of several wild populations, and the number of plants in the existing populations is low. Study of the genetic structure, distribution pattern, and historical dynamics of I. yunguiensis in all areas of its distribution is of guiding significance for its rational and effective protection. Methods Expressed sequence tag-simple sequence repeat (EST-SSR) markers were used to study the genetic diversity and structure of I. yunguiensis, and noncoding chloroplast DNA (cpDNA) sequences were used to study the pedigree, population dynamics history, and glacial shelter of I. yunguiensis. A maximum entropy model was used to predict the past, present, and future distribution patterns of I. yunguiensis. Results Analysis with EST-SSR markers revealed that I. yunguiensis showed high genetic diversity and that genetic variation was significantly higher within populations than between populations. Based on cpDNA data, it was concluded that there was no significant geographic pedigree in the whole area of I. yunguiensis distribution (NST = 0.344 > GST = 0.183, p > 0.05); 21 haplotypes were detected using DnaSP v5. Neutral test and LAMARC simulation showed that I. yunguiensis has experienced rapid expansion in recent years. The maximum entropy model predicted that the potential distribution area of I. yunguiensis in the last glacial maximum period has increased significantly compared with the present distribution area, but the future distribution area did not show substantial changes.

In this study, mating system, genetic diversity, and genetic structure of the endangered endemic aquatic Isoetes yunguiensis in China was investigated using ISSR markers. The results of ISSR analyses showed that the estimate of multilocus outcrossing rate (tm) was high at species level (tm = 0.955), indicating that diploid I. yunguiensis is a predominant outcrossing species. Nine selected ISSR primers used in the study amplified 66 reproducible bands, 41 of which were polymorphic among 37 individuals. High level of genetic diversity was detected at the species level (PPB = 62.12%), whereas, relatively low genetic diversity existed within populations (PPB = 39.39%). Analysis of molecular variance (AMOVA) revealed that 31.99% of the genetic variation was attributable to differences between populations and the rest (68.01%) to variability within populationsof I. yunguiensis. Value of Fst (0.320) indicated that genetic differentiation between populations also was significant. These results showed that I. yunguiensis predominantly favors crossing, and has a high level of genetic diversity and highly significant genetic variation between and within populations. Gene flow (Nm) among populations is equal to 1.177. High outcrossing rates may be responsible for the high levels of genetic diversity observed in the I. yunguiensis population. To maintain the current level of genetic diversity for this species, we recommend increasing in situ conservation sites. [ABSTRACT FROM AUTHOR]

Isoetes yunguiensis is a rare and endangered fern endemic to Yunnan–Guizhou Plateau, China. The complete chloroplast genome sequence of I. yunguiensis was generated by de novo assembly using whole genome next-generation sequencing. The cp genome of I. yunguiensis was a circular structure and 145,355 bp in length, comprising a pair of inverted repeat (IR) regions of 26,130 bp, a large single copy (LSC) of 91,923 bp, and a small single copy (SSC) of 27,302 bp. The genome encoded 124 unique genes consisting of 82 protein-coding genes, 32 transfer RNA, four ribosomal RNA genes, and six pseudogenes. A maximum-likelihood phylogenetic analysis revealed that I. yunguiensis was closely related to I. butleri, I. engelmannii, I. flaccida, I. melanospora, and I. valida, with strong support values.

Abstract.— In this study, mating system, genetic diversity, and genetic structure of the endangered endemic aquatic lycophyte Isoëtes yunguiensis in China was investigated using AFLP markers. The estimates of outcrossing rates (tm = 1.200) indicate that diploid I. yunguiensis is a predominantly outcrossing species. Six selected AFLP primer pairs used in the study amplified 195 reproducible bands, 160 of which were polymorphic (PPB = 82.05%), indicating significant genetic diversity at the species level. AMOVA revealed that 40.12% of the genetic variation was attributable to differences between populations and the rest (59.88%) to variability within populations. High outcrossing rates and the historical accumulation of genetic variation may be responsible for the high levels of genetic diversity observed in the I. yunguiensis population. To maintain the current level of genetic diversity for this species, we recommend increasing in situ conservation sites. [ABSTRACT FROM AUTHOR]

Isoetes yunguiensis is a rare and endangered fern endemic to Yunnan–Guizhou Plateau, China. The complete chloroplast genome sequence of I. yunguiensis was generated by de novo assembly using whole genome next-generation sequencing. The cp genome of I. yunguiensis was a circular structure and 145,355 bp in length, comprising a pair of inverted repeat (IR) regions of 26,130 bp, a large single copy (LSC) of 91,923 bp, and a small single copy (SSC) of 27,302 bp. The genome encoded 124 unique genes consisting of 82 protein-coding genes, 32 transfer RNA, four ribosomal RNA genes, and six pseudogenes. A maximum-likelihood phylogenetic analysis revealed that I. yunguiensis was closely related to I. butleri, I. engelmannii, I. flaccida, I. melanospora, and I. valida, with strong support values. [ABSTRACT FROM AUTHOR]

Background: Isoetes yunguiensis Q. F. Wang & W. C. Taylor is a lycophyte of an ancient genus, and it is endemic to China. It is a first-class protected plant in China. This living fossil is used in paleoecology and studies on the evolution of Lycophytes in the Yunnan-Guizhou Plateau. In recent years, human activities have caused the disappearance of several wild populations, and the number of plants in the existing populations is low. Study of the genetic structure, distribution pattern, and historical dynamics of I . yunguiensis in all areas of its distribution is of guiding significance for its rational and effective protection., Methods: Expressed sequence tag-simple sequence repeat (EST-SSR) markers were used to study the genetic diversity and structure of I . yunguiensis , and noncoding chloroplast DNA (cpDNA) sequences were used to study the pedigree, population dynamics history, and glacial shelter of I. yunguiensis . A maximum entropy model was used to predict the past, present, and future distribution patterns of I. yunguiensis ., Results: Analysis with EST-SSR markers revealed that I. yunguiensis showed high genetic diversity and that genetic variation was significantly higher within populations than between populations. Based on cpDNA data, it was concluded that there was no significant geographic pedigree in the whole area of I. yunguiensis distribution (NST = 0.344 >  GST = 0.183, p  > 0.05); 21 haplotypes were detected using DnaSP v5. Neutral test and LAMARC simulation showed that I. yunguiensis has experienced rapid expansion in recent years. The maximum entropy model predicted that the potential distribution area of I. yunguiensis in the last glacial maximum period has increased significantly compared with the present distribution area, but the future distribution area did not show substantial changes., Competing Interests: The authors declare there are no competing interests., (©2020 Zheng et al.)