The genus Lespedeza (tribe: Desmodieae) consists of about 40 species that have high medicinal and economic value. However, in this genus, using morphological characters, the species identification is quite complicated, which can be solved by the analysis of the complete chloroplast genomes. As primary organelle genomes, the complete genome sequences of chloroplasts (cp) provide unique molecular information to study the divergence of species, RNA editing, and phylogeny. Therefore, to the best of our knowledge, for the first time, we sequenced the complete cp genomes of two representative Lespedeza species: Lespedeza davurica and Lespedeza cuneata. The cp genomes of both the species were found to be 149,010 bp in length, exhibiting the typical angiosperm chloroplast structure containing four regions. The Lespedeza cp genomes showed similar conserved gene contents, order, and orientations with a total GC content of 35.0%. A total of 128 genes, including 83 protein-coding genes, 37 tRNAs, and eight rRNAs, were identified from each genome. Unique molecular features of the two Lespedeza cp genome sequences were obtained by performing the analysis of repeats, sequence divergence, codon usage, and predicting the RNA editing sites in addition to phylogenetic analysis with other key genera in tribe Desmodieae. Using the two datasets, the phylogenetic relationship of Lespedeza species among Deasmodieae was discovered, suggesting that whole cp genomes provided useful information for phylogenetic studies of these species.

The anther cuticle and pollen wall function as physical barriers that protect genetic material from various environmental stresses. The anther cuticle is composed of wax and cutin, the pollen wall includes exine and intine, and the components of the outer exine are collectively called sporopollenin. Other than cuticle wax, cutin and sporopollenin are biopolymers compounds. The precise constituents and developmental mechanism of these biopolymeric are poorly understood. Here, we reported a complete male sterile mutant, male sterile6021, in maize. The mutant displayed a smooth anther surface and irregular pollen wall formation before anthesis, and its tapetum was degraded immaturely. Gas chromatography-mass spectrometry analysis revealed a severe reduction of lipid derivatives in the mutant anther. We cloned the gene by map based cloning. It encoded a fatty acyl carrier protein reductase that was localized in plastids. Expression analysis indicated that MS6021 was mainly expressed in the tapetum and microspore after the microspore was released from the tetrad. Functional complementation of the orthologous Arabidopsis mutant demonstrated that MS6021 is conserved between monocots and dicots and potentially even in flowering plants. MS6021 plays a conserved, essential role in the successful development of anther cuticle and pollen exine in maize.

Eragrostis of the tribe Eragrostideae is a taxonomically complex genus, because of its polyploid nature and the presence of similar morphological characters among its species. However, the relationship between these morphologically indistinguishable species at the genomic level has not yet been investigated. Here, we report the complete chloroplast genome of E. pilosa and compare its genome structures, gene contents, simple sequence repeats (SSRs), sequence divergence, codon usage bias, and Kimura 2-parameter (K2P) interspecific genetic distances with those of other Eragrostideae species. The E. pilosa chloroplast genome was 134,815 bp in length and contained 132 genes and four regions, including a large single-copy region (80,100 bp), a small single-copy region (12,661 bp), and a pair of inverted repeats (21,027 bp). The average nucleotide diversity between E. pilosa and E. tef was estimated to be 0.011, and 0.01689 among all species. The minimum and maximum K2P interspecific genetic distance values were identified in psaA (0.007) and matK (0.029), respectively. Of 45 SSRs, eight were shared with E. tef, all of which were in the LSC region. Phylogenetic analysis resolved the monophyly of the sampled Eragrostis species and confirmed the close relationship between E. pilosa and E. tef. This study provides useful chlorophyll genomic information for further species identification and phylogenetic reconstruction of Eragrostis species.