Muhammad Awais Ghani

The role of small RNAs on phenotypes in reciprocal hybrids between Solanum lycopersicum and S. pimpinellifolium.

BackgroundReciprocal hybrids showing different phenotypes have been well documented in previous studies, and many factors accounting for different phenotypes have been extensively investigated. However, less is known about whether the profiles of small RNAs differ between reciprocal hybrids and how these small RNAs affect gene expression and phenotypes. To better understand this mechanism, the role of small RNAs on phenotypes in reciprocal hybrids was analysed.ResultsReciprocal hybrids between Solanum lycopersicum cv. Micro-Tom and S. pimpinellifolium line WVa700 were generated. Significantly different phenotypes between the reciprocal hybrids were observed, including fruit shape index, single fruit weight and plant height. Then, through the high-throughput sequencing of small RNAs, we found that the expression levels of 76 known miRNAs were highly variable between the reciprocal hybrids. Subsequently, a total of 410 target genes were predicted to correspond with these differentially expressed miRNAs. Furthermore, gene ontology (GO) annotation indicated that those target genes are primarily involved in metabolic processes. Finally, differentially expressed miRNAs, such as miR156f and 171a, and their target genes were analysed by qRT-PCR, and their expression levels were well correlated with the different phenotypes.ConclusionsThis study showed that the profiles of small RNAs differed between the reciprocal hybrids, and differentially expressed genes were also observed based on the different phenotypes. The qRT-PCR results of target genes showed that differentially expressed miRNAs negatively regulated their target genes. Moreover, the expression of target genes was well correlated with the observations of different phenotypes. These findings may aid in elucidating small RNAs contribute significantly to different phenotypes through epigenetic modification during reciprocal crossing.

Hybrid Technology in Cruciferous Vegetables

Use of male sterile plants has become an important technique in heterosis breeding,which simplify and reduce the cost of hybrid seed production. Cruciferous vegetables are very important crops in the world, and two types of male sterility have been mainly explored in cruciferous vegetables (1) nuclear male sterility, this kind of male sterility is controlled by the dominant or recessive nuclear genes, and its sterility is easy to be restored, but difficult to maintained; (2) cytoplasmic male sterility, in which male sterility is controlled by a particular cytoplasmic male sterile gene (S). Cytoplasmic male sterility is easy to be maintained but complicated to be recovered. Male sterility can be produced by different ways; natural mutation, wide hybridization, and protoplast fusion. Ogu CMS and Polma CMS were found in radish and B. napus respectively by natural mutations. Among the male sterile materials, most of them were obtained by the wide hybridization among varieties, species and genera. CMS cabbage was produced by the fusion of leaf protoplasts from fertile cabbage and CMS Ogura broccoli lines. The Pol CMS had been transferred from CMS B. napus to Chinese cabbage. Chinese breeders produced many cabbage varieties after introduced male sterility from other materials. A new cabbage hybrid varieties Zhonggan no.16, 17 and 18 were produced by hybridization of dominant genic male sterility line and inbred line in China. A stable CMS line of tuber mustard was developed by distant crosses and subsequent backcrosses and induced 100 % male sterility. To date, extensive efforts have been made on identification of male sterility systems and the possibilities of development of hybrids in application.

The high-throughput sequencing of small RNAs profiling in wide hybridisation and allopolyploidisation between Brassica rapa and Brassica nigra

Small RNAs play an important role in maintaining the genome reconstruction and stability in the plant. However, little is known regarding the role of small RNAs during the process of wide hybridisation and chromosome doubling. Therefore, the changes in the small RNAs were assessed during the formation of an allodiploid (genome: AB) and its allotetraploid (genome: AABB) between Brassica rapa (♀) and Brassica nigra (♂) in the present study. Here, the experimental methods described in details, RNA-seq data (available at Gene Expression Omnibus database under GSE61872) and analysis published by Ghani et al. [1]. The study showed that small RNAs play an important role in maintaining the genome stability, and regulate gene expression which induces the phenotype variation in the formation of an allotetraploid. This may play an important role in the occurrence of heterosis in the allotetraploid.