Intergenomic Rearrangements after Polyploidization of Kengyilia thoroldiana (Poaceae: Triticeae) Affected by Environmental Factors

Polyploidization is a major evolutionary process. Approximately 70–75% species of Triticeae (Poaceae) are polyploids, involving 23 genomes. To investigate intergenomic rearrangements after polyploidization of Triticeae species and to determine the effects of environmental factors on them, nine populations of a typical polyploid Triticeae species, Kengyilia thoroldiana (Keng) J.L.Yang et al. (2n = 6x = 42, StStPPYY), collected from different environments, were studied using genome in situ hybridization (GISH). We found that intergenomic rearrangements occurred between the relatively large P genome and the small genomes, St (8.15%) and Y (22.22%), in polyploid species via various types of translocations compared to their diploid progenitors. However, no translocation was found between the relatively small St and Y chromosomes. Environmental factors may affect rearrangements among the three genomes. Chromosome translocations were significantly more frequent in populations from cold alpine and grassland environments than in populations from valley and lake-basin habitats (P<0.05). The relationship between types of chromosome translocations and altitude was significant (r = 0.809, P<0.01). Intergenomic rearrangements associated with environmental factors and genetic differentiation of a single basic genome should be considered as equally important genetic processes during species' ecotype evolution

Continuous Leaf Area Index (LAI) Observation in Forests: Validation, Application, and Improvement of LAI-NOS

The leaf area index (LAI) is one of the core parameters reflecting the growth status of vegetation. The continuous long-term observation of the LAI is key when assessing the dynamic changes in the energy exchange of ecosystems and the vegetation’s response indicators to climate change. The errors brought about by non-standard operations in manual LAI measurements hinder the further research utilization of this parameter. The long-term automatic LAI observation network is helpful in reducing errors from manual measurements. To further test the applicability of automatic LAI observation instruments in forest environments, this study carried out comparative validation research of the LAI-NOS (LAI automatic network observation system) at the Wanglang Mountain Ecological Remote Sensing Comprehensive Observation Station, China, comparing it with the results measured by the LAI-2200 Plant Canopy Analyzer (LI-COR, Lincoln, NE, USA), the LAI-probe handheld instrument, and a fisheye lens digital camera (DHP method). Instead of using the original “smoothest window” method, a new method, the “sunrise–sunset” method, is used to extract daily LAI-NOS LAI, and the corresponding confidence level is used to filter the data. The results of the data analysis indicate the following: LAI-NOS has a high data stability. The automatically acquired daily data between two consecutive days has a small deviation and significant correlations. Single-angle/multi-angle LAI measurement results of the LAI-NOS have good correlations with the LAI-2200 (R2 = 0.512/R2 = 0.652), the LAI-probe (R2 = 0.692/R2 = 0.619), and the DHP method (R2 = 0.501/R2 = 0.394). The daily LAI obtained from the improved method, when compared to the original method, both show the same vegetation growth trend. However, the improved method has a smaller dispersion. This study confirms the stability and accuracy of automatic observation instruments in mountainous forests, demonstrating the distinct advantages of automatic measurement instruments in the long-term ground observation of LAIs

Population Structure and Genetic Diversity Analysis in Sugarcane (Saccharum spp. hybrids) and Six Related Saccharum Species

Sugarcane (Saccharum spp. hybrids) is one of the most important commercial crops for sugar, ethanol, and other byproducts production; therefore, it is of great significance to carry out genetic research. Assessing the genetic population structure and diversity plays a vital role in managing genetic resources and gene mapping. In this study, we assessed the genetic diversity and population structure among 196 Saccharum accessions, including 34 S. officinarum, 69 S. spontaneum, 17 S. robustum, 25 S. barberi, 13 S. sinense, 2 S. edule, and 36 Saccharum spp. hybrids. A total of 624 polymorphic SSR alleles were amplified by PCR with 22 pairs of fluorescence-labeled highly polymorphic SSR primers and identified on a capillary electrophoresis (CE) detection system including 109 new alleles. Three approaches (model-based clustering, principal component analysis, and phylogenetic analysis) were conducted for population structure and genetic diversity analyses. The results showed that the 196 accessions could be grouped into either three (Q) or eight (q) sub-populations. Phylogenetic analysis indicated that most accessions from each species merged. The species S. barberi and S. sinense formed one group. The species S. robustum, S. barberi, S. spontaneum, S. edule, and sugarcane hybrids merged into the second group. The S. officinarum accessions formed the third group located between the other two groups. Two-way chi-square tests derived a total of 24 species-specific or species-associated SSR alleles, including four alleles each for S. officinarum, S. spontaneum, S. barberi, and S. sinense, five alleles for S. robustum. and three alleles for Saccharum spp. hybrids. These species-specific or species-associated SSR alleles will have a wide application value in sugarcane breeding and species identification. The overall results provide useful information for future genetic study of the Saccharum genus and efficient utilization of sugarcane germplasm resources in sugarcane breeding

Population Structure and Genetic Diversity Analysis in Sugarcane (<i>Saccharum</i> spp. hybrids) and Six Related <i>Saccharum</i> Species

Sugarcane (Saccharum spp. hybrids) is one of the most important commercial crops for sugar, ethanol, and other byproducts production; therefore, it is of great significance to carry out genetic research. Assessing the genetic population structure and diversity plays a vital role in managing genetic resources and gene mapping. In this study, we assessed the genetic diversity and population structure among 196 Saccharum accessions, including 34 S. officinarum, 69 S. spontaneum, 17 S. robustum, 25 S. barberi, 13 S. sinense, 2 S. edule, and 36 Saccharum spp. hybrids. A total of 624 polymorphic SSR alleles were amplified by PCR with 22 pairs of fluorescence-labeled highly polymorphic SSR primers and identified on a capillary electrophoresis (CE) detection system including 109 new alleles. Three approaches (model-based clustering, principal component analysis, and phylogenetic analysis) were conducted for population structure and genetic diversity analyses. The results showed that the 196 accessions could be grouped into either three (Q) or eight (q) sub-populations. Phylogenetic analysis indicated that most accessions from each species merged. The species S. barberi and S. sinense formed one group. The species S. robustum, S. barberi, S. spontaneum, S. edule, and sugarcane hybrids merged into the second group. The S. officinarum accessions formed the third group located between the other two groups. Two-way chi-square tests derived a total of 24 species-specific or species-associated SSR alleles, including four alleles each for S. officinarum, S. spontaneum, S. barberi, and S. sinense, five alleles for S. robustum. and three alleles for Saccharum spp. hybrids. These species-specific or species-associated SSR alleles will have a wide application value in sugarcane breeding and species identification. The overall results provide useful information for future genetic study of the Saccharum genus and efficient utilization of sugarcane germplasm resources in sugarcane breeding

Production and Identification of Wheat-Agropyron cristatum 2P Translocation Lines.

Agropyron cristatum (L.) Gaertn. (2n = 28, PPPP), a wild relative of common wheat, possesses many potentially valuable traits that can be transferred to common wheat through breeding programs. The wheat-A. cristatum disomic addition and translocation lines can be used as bridge materials to introduce alien chromosomal segments to wheat. Wheat-A. cristatum 2P disomic addition line II-9-3 was highly resistant to powdery mildew and leaf rust, which was reported in our previous study. However, some translocation lines induced from II-9-3 have not been reported. In this study, some translocation lines were induced from II-9-3 by 60Co-γ irradiation and gametocidal chromosome 2C and then identified by cytological methods. Forty-nine wheat-A. cristatum translocation lines were obtained and various translcoation types were identified by GISH (genomic in situ hybridization), such as whole-arm, segmental and intercalary translocations. Dual-color FISH (fluorescent in situ hybridization) was applied to identify the wheat chromosomes involved in the translocations, and the results showed that A. cristatum 2P chromosome segments were translocated to the different wheat chromosomes, including 1A, 2A, 3A, 4A, 5A, 6A, 7A, 3B, 5B, 7B, 1D, 4D and 6D. Many different types of wheat-A. cristatum alien translocation lines would be valuable for not only identifying and cloning A. cristatum 2P-related genes and understanding the genetics and breeding effects of the translocation between A. cristatum chromosome 2P and wheat chromosomes, but also providing new germplasm resources for the wheat genetic improvement

Efficient induction of Wheat-agropyron cristatum 6P translocation lines and GISH detection.

The narrow genetic background restricts wheat yield and quality improvement. The wild relatives of wheat are the huge gene pools for wheat improvement and can broaden its genetic basis. Production of wheat-alien translocation lines can transfer alien genes to wheat. So it is important to develop an efficient method to induce wheat-alien chromosome translocation. Agropyroncristatum (P genome) carries many potential genes beneficial to disease resistance, stress tolerance and high yield. Chromosome 6P possesses the desirable genes exhibiting good agronomic traits, such as high grain number per spike, powdery mildew resistance and stress tolerance. In this study, the wheat-A. cristatum disomic addition was used as bridge material to produce wheat-A. cristatum translocation lines induced by (60)Co-γirradiation. The results of genomic in situ hybridization showed that 216 plants contained alien chromosome translocation among 571 self-pollinated progenies. The frequency of translocation was 37.83%, much higher than previous reports. Moreover, various alien translocation types were identified. The analysis of M2 showed that 62.5% of intergeneric translocation lines grew normally without losing the translocated chromosomes. The paper reported a high efficient technical method for inducing alien translocation between wheat and Agropyroncristatum. Additionally, these translocation lines will be valuable for not only basic research on genetic balance, interaction and expression of different chromosome segments of wheat and alien species, but also wheat breeding programs to utilize superior agronomic traits and good compensation effect from alien chromosomes

Types and frequencies of chromosome translocation in nine populations of <i>K. thoroldiana</i>.

<p>(P/Y)_t: number of individual plants with terminal translocations between chromosomes P and Y;</p><p>(P/Y)_w: number of individual plants with whole-arm translocations between chromosomes P and Y;</p><p>(P/St)_t: number of individual plants with terminal translocations between chromosomes P and St;</p><p>(P/St)_i: number of individual plants with intercalary translocations between chromosomes P and St.</p><p>Tr_t: number of individual plants with all terminal translocations.</p><p>Tr_w: number of individual plants with all whole-arm translocations.</p

Figure 3

<p>The ratio of different types of translocated chromosome in M₁ and M₂ generation.</p

Dual-color FISH/GISH identification of the homoeologous group of partially translocated wheat chromosomes.

<p><b>A</b>_<b>1</b><b>-R</b>_<b>1</b>: GISH patterns of wheat-<i>A</i>. <i>cristatum</i> translocation lines. Total genomic DNA of <i>A</i>. <i>cristatum</i> was labelled with digoxigenin-11-dUTP and visualized with red fluorescence. Chromosomes were counterstained with DAPI and visualized with blue fluorescence. <b>A</b>_<b>2</b><b>-R</b>_<b>2</b>: FISH patterns of wheat-<i>A</i>. <i>cristatum</i> translocation lines. <b>A</b>_<b>2</b><b>-N</b>_<b>2</b>, <b>P</b>_<b>2</b><b>-R</b>_<b>2</b>: The repetitive sequence clone pHvG39 was labelled with biotin-16-dUTP and visualized with green fluorescence; <b>O</b>_<b>2</b>: The repetitive sequence clone pSc119.2 was labelled with biotin-16-dUTP and visualized with green fluorescence. The repetitive sequence clone pAs1 was labelled with digoxigenin-11-dUTP and visualized with red fluorescence. Chromosomes were counterstained with DAPI and visualized with blue fluorescence. Arrows point to the translocated chromosomes. <b>A.</b> 2<b>P</b>-23; <b>B.</b> 2<b>P</b>-35; <b>C.</b> 2<b>P</b>-40; <b>D.</b> 2<b>P</b>-43; <b>E.</b> 2<b>P</b>-48; <b>F.</b> 2<b>P</b>-55; <b>G.</b> 2<b>P</b>-80; <b>H.</b> 2<b>P</b>-116; <b>I.</b> 2<b>P</b>-122; <b>J.</b> 2<b>P</b>-167; <b>K.</b> 2<b>P</b>-173; <b>L.</b> 2<b>P</b>-187; <b>M.</b> 2<b>P</b>-190; <b>N.</b> 2<b>P</b>-205; <b>O.</b> 2<b>P</b>-213; <b>P.</b> 2<b>P</b>-269; <b>Q.</b> 2<b>P</b>-355; <b>R.</b> 2<b>P</b>-367.</p