Intron splicing in 5' untranslated region of the rolA transcript in transgenic apple

In the interkingdom horizontal gene transfer, the small rolA gene is a big mystery

The biological function of the agrobacterial oncogene rolA is very poorly understood compared to other components of the mechanism of horizontal gene transfer during agrobacterial colonization of plants. Research groups around the world have worked on this problem, and available information is reviewed in this review, but other rol oncogenes have been studied much more thoroughly. Having one unexplored element makes it impossible to form a complete picture. However, the limited data suggest that the rolA oncogene and its regulatory apparatus have great potential in plant biotechnology and genetic engineering. Here, we collect and discuss available experimental data about the function and structure of rolA. There is still no clear understanding of the mechanism of RolA and its structure and localization. We believe this is because of the nucleotide structure of a frameshift in the most well-studied rolA gene of the agropine type pRi. In fact, interest in the genes of agrobacteria as natural tools for the phenotypic or biochemical engineering of plants increased. We believe that a detailed understanding of the molecular mechanisms will be forthcoming. KEY POINTS: • Among pRi T-DNA oncogenes, rolA is the least understood in spite of many studies. • Frameshift may be the reason for the failure to elucidate the role of agropine rolA. • Understanding of rolA is promising for the phenotypic and biochemical engineering of plants.

A Genetic Linkage Map of BC2 Population Reveals QTL Associated with Plant Architecture Traits in Lagerstroemia

Plant architecture improvement is of great significance in influencing crop yield, harvesting efficiency and ornamental value, by changing the spatial structure of the canopy. However, the mechanism on plant architecture in woody plants is still unclear. In order to study the genetic control of plant architecture traits and promote marker-assisted selection (MAS), a genetic linkage map was constructed, and QTL mapping was performed. In this study, using 188 BC2 progenies as materials, a genetic map of Lagerstroemia was constructed using amplification fragment length polymorphisms (AFLP) and simple sequence repeats (SSR) markers, and the QTLs of four key plant architecture traits (plant height, crown width, primary lateral branch height and internode length) were analyzed. The genetic map contains 22 linkage groups, including 198 AFLP markers and 36 SSR markers. The total length of the genome covered by the map is 1272 cM, and the average distance between markers is 6.8 cM. Three QTLs related to plant height were located in LG1, LG4 and LG17 linkage groups, and the phenotypic variation rates were 32.36, 16.18 and 12.73%, respectively. A QTL related to crown width was located in LG1 linkage group, and the phenotypic variation rate was 18.07%. Two QTLs related to primary lateral branch height were located in the LG1 and LG7 linkage groups, and the phenotypic variation rates were 20.59 and 15.34%, respectively. Two QTLs related to internode length were located in the LG1 and LG20 linkage groups, and the phenotypic variation rates were 14.86 and 9.87%. The results provide a scientific basis for finely mapping genes of plant architecture traits and marker-assisted breeding in Lagerstroemia.

Molecular characterization of Quercus suber MYB1, a transcription factor up-regulated in cork tissues

The molecular processes associated with cork development in Quercus suber L. are poorly understood. A previous molecular approach identified a list of genes potentially important for cork formation and differentiation, providing a new basis for further molecular studies. This report is the first molecular characterization of one of these candidate genes, QsMYB1, coding for an R2R3-MYB transcription factor. The R2R3-MYB gene sub-family has been described as being involved in the phenylpropanoid and lignin pathways, both involved in cork biosynthesis. The results showed that the expression of QsMYB1 is putatively mediated by an alternative splicing (AS) mechanism that originates two different transcripts (QsMYB1.1 and QsMYB1.2), differing only in the 5'-untranslated region, due to retention of the first intron in one of the variants. Moreover, within the retained intron, a simple sequence repeat (SSR) was identified. The upstream regulatory region of QsMYB1 was extended by a genome walking approach, which allowed the identification of the putative gene promoter region. The relative expression pattern of QsMYB1 transcripts determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) revealed that both transcripts were up-regulated in cork tissues; the detected expression was several times higher in newly formed cork harvested from trees producing virgin, second or reproduction cork when compared with wood. Moreover, the expression analysis of QsMYB1 in several Q. suber organs showed very low expression in young branches and roots, whereas in leaves, immature acorns or male flowers, no expression was detected. These preliminary results suggest that QsMYB1 may be related to secondary growth and, in particular, with the cork biosynthesis process with a possible alternative splicing mechanism associated with its regulatory function.