Molecular diversity analysis in hexaploid wheat (Triticum aestivum L.) and two Aegilops species (Aegilops crassa and Aegilops cylindrica) using CBDP and SCoT markers

Background Evaluation of genetic diversity and relationships among crop wild relatives is an important task in crop improvement. The main objective of the current study was to estimate molecular variability within the set of 91 samples from Triticum aestivum, Aegilops cylindrica, and Aegilops crassa species using 30 CAAT box–derived polymorphism (CBDP) and start codon targeted (SCoT) markers. Results Fifteen SCoT and Fifteen CBDP primers produced 262 and 298 fragments which all of them were polymorphic, respectively. The number of polymorphic bands (NPB), polymorphic information content (PIC), resolving power (Rp), and marker index (MI) for SCoT primers ranged from 14 to 23, 0.31 to 0.39, 2.55 to 7.49, and 7.56 to 14.46 with an average of 17.47, 0.34, 10.44, and 5.69, respectively, whereas these values for CBDP primers were 15 to 26, 0.28 to 0.36, 3.82 to 6.94, and 4.74 to 7.96 with a mean of 19.87, 0.31, 5.35, and 6.24, respectively. Based on both marker systems, analysis of molecular variance (AMOVA) indicated that the portion of genetic diversity within species was more than among them. In both analyses, the highest values of the number of observed (Na) and effective alleles (Ne), Nei’s gene diversity (He), and Shannon’s information index (I) were estimated for Ae. cylindrica species. Conclusion The results of cluster analysis and population structure showed that SCoT and CBDP markers grouped all samples based on their genomic constitutions. In conclusion, the used markers are very effective techniques for the evaluation of the genetic diversity in wild relatives of wheat.

Comparative transcriptome analysis revealed the conversions of stamens into pistil-like structures in Aegilops crassa cytoplasmic male sterile wheat (Triticum aestivum)

Background: Aegilops crassa cytoplasm is an essential material for investigating the cytoplasm of cytoplasmic male sterility (CMS). Moreover, the stamens of C303A exhibit a high degree of pistillody, turning almost white. However, the underlying molecular mechanism of C303A pistillody remains unclear. Therefore, to gain a better understanding of C303A, the phenotypic and cytological features of C303A were observed to identify the key stage that the homeotic transformation of stamens into pistil-like structures, transcriptome profiles were determined by Illumina RNA sequencing technology (RNA-Seq) of stamen. Results: Through morphological observation, for CMS wheat with Aegilops crassa cytoplasm (CMS-C) line C303A, the pistil of which developed normally, but stamens were ultimately aborted and the stamens released no pollen when mature. According to the results of the paraffin section, stamens began to transform into pistils or pistil-like structures at binucleate stage (BNS). Therefore, the stamens of line C303A and its maintainer 303B at BNS were collected for transcriptome sequencing. A total of 20,444 wheat genes were detected as being differentially expressed between C303A and 303B stamens, included 10,283 up-regulated and 10,161 down-regulated genes. Gene Ontology Enrichment Analyses showed that most differentially expressed genes (DEGs) distributed on the metabolic process, cell, cellular process, catalytic activity and cell part. From KEGG, we knew that DEGs were mainly enriched to energy metabolism. We also found several essential genes that may contribute to pistillody in C303A. Based on the above analysis, we believe that due to the confusion of energy metabolism and reactive oxygen metabolism, thereby inducing the pistillody and eventually lead to the abortion of C303A. Conclusion:This study unravels the complex transcriptome profiles in C303A stamen, highlighting the energy metabolism and class B MADS-box genes related to pistillody. This work should lay the foundations of future studies in the mechanical response to wheat stamen and pollen development in CMS.

NOMENCLATURAL TYPES OF THE TAXA NAMED AFTER N. I. VAVILOV IN THE HERBARIUM COLLECTION OF VIR (WIR)

Carl Linnaeus believed, even in his time, that na-mes of eminent scientists may serve as a good source to generate plant names. In 2017, the 130th birthday anniversary of Nikolai Ivanovich Vavilov, an outstanding biologist of the twentieth century, was celebrated. The magnitude of his personality and his tremendous contribution to the knowledge of the world’s diversity of cultivated plants and their wild relatives compelled many taxonomists to use Vavilov’s name while naming new plant taxa. All in all, 28 botanical taxa with Vavilov’s name have been made public: one genus and 27 species, including intraspecific taxa. One third of them are taxa within the genus Triticum L. (one species, one subspecies, and seven varieties). Nomenclatural types of seven taxa are preserved in VIR’s herbarium (WIR). These are represented by holotypes and mesotypes: Aegilops crassa subsp. vavilovii Zhuk. (≡ A. vavilovii (Zhuk.) Chennav.) and Triticum spelta subsp. kuckuckianum var. vavilovii Dorof.; lectotypes and isolectotypes: Avena strigosa subsp. vaviloviana Malz. (≡ A. vaviloviana (Malz.) Mordv.) and Solanum vavilovii Juz. et Buk.; and neotypes: Triticum aestivum var. vavilovianum Jakubz., T. dicoccoides var. vavilovii Jakubz., and T. vulgare var. vavilovii Thum. (≡ T. vavilovii (Thum.) Jakubz.).

Comparative transcriptome analysis revealed the conversions of stamens into pistil-like structures in Aegilops crassa cytoplasmic male sterile wheat (Triticum aestivum)

Background: Aegilops crassa cytoplasm is an essential material for investigating the cytoplasm of cytoplasmic male sterility (CMS). Moreover, the stamens of C303A exhibit a high degree of pistillody, turning almost white. However, the underlying molecular mechanism of C303A pistillody remains unclear. Therefore, to gain a better understanding of C303A, the phenotypic and cytological features of C303A were observed to identify the key stage that the homeotic transformation of stamens into pistil-like structures, transcriptome profiles were determined by Illumina RNA sequencing technology (RNA-Seq) of stamen. Results: Through morphological observation, for CMS wheat with Aegilops crassa cytoplasm (CMS-C) line C303A, the pistil of which developed normally, but stamens were ultimately aborted and the stamens released no pollen when mature. According to the results of the paraffin section, stamens began to transform into pistils or pistil-like structures at binucleate stage (BNS). Therefore, the stamens of line C303A and its maintainer 303B at BNS were collected for transcriptome sequencing. A total of 20,444 wheat genes were detected as being differentially expressed between C303A and 303B stamens, included 10,283 up-regulated and 10,161 down-regulated genes. Gene Ontology Enrichment Analyses showed that most differentially expressed genes (DEGs) distributed on the metabolic process, cell, cellular process, catalytic activity and cell part. From KEGG, we knew that DEGs were mainly enriched to energy metabolism. We also found several essential genes that may contribute to pistillody in C303A. Based on the above analysis, we believe that due to the confusion of energy metabolism and reactive oxygen metabolism, thereby inducing the pistillody and eventually lead to the abortion of C303A. Conclusion:This study unravels the complex transcriptome profiles in C303A stamen, highlighting the energy metabolism and class B MADS-box genes related to pistillody. This work should lay the foundations of future studies in the mechanical response to wheat stamen and pollen development in CMS.