A systematic dissection in oilseed rape provides insights into the genetic architecture and molecular mechanism of yield heterosis

Heterosis refers to the better performance of cross progeny compared with inbred parents, and its utilization contributes greatly to agricultural production. Several hypotheses have been proposed to explain heterosis mainly including dominance, over-dominance (or pseudo-overdominance) and epistasis. However, systematic dissection and verification of these hypotheses are rarely documented. Here, comparison of heterosis level across different traits showed that the strong heterosis of composite traits (such as yield) could be attributed to the multiplicative effects of moderate heterosis of component traits, whether at the genome or locus level. Yield heterosis was regulated by a complex trait-QTL network that was characterized by obvious centre-periphery structure, hub QTL, complex up/downstream and positive/negative feedback relationships. More importantly, we showed that better-parent heterosis on yield could be produced in a cross of two near-isogenic lines by the pyramiding and complementation of two major heterotic QTL showing partial-dominance on yield components. The causal gene (BnaA9.CYP78A9) of QC14 was identified, and its heterotic effect results from the heterozygous status of a CACTA-like transposable element in its upstream regulatory region, which led to partial dominance at expression and auxin levels, thus resulting in non-additive expression of downstream responsive genes involved in cell cycle and proliferation, eventually leading to the heterosis of cell number. Taken together, the results at the phenotypic, genetic and molecular levels were highly consistent, which demonstrated that the pyramiding effect of heterotic QTL and the multiplicative effect of individual component traits could well explain substantial parts of yield heterosis in oilseed rape. These results provide in-depth insights into the genetic architecture and molecular mechanism of yield heterosis.     

Factors Affecting Bacterial Adhesion on Selected Textile Fibres

In sectors like healthcare and hospitality, it has been realized that fabrics play a pivotal role in transfer of nosocomial infections. However, there is a major gap in drawing correlation between different fibre types and their interaction with microorganisms. Such information is important to formulate guidelines for textile materials for use in these sectors. In the current study, the adherence of four important bacteria, Staphylococcus aureus, Acinetobacter calcoaceticus, Escherichia coli, and Pseudomonas aeruginosa was studied on six different fibre types namely polyester, wool, polypropylene, viscose, silk and cotton. Among these fibres, viscose showed maximum adherence while silk fibres showed the least attachment of bacterial strains. Bacterial adhesion was correlated with the surface characteristics (surface charge, hydrophobicity etc.) of bacteria, and nanoroughness of fibres. Adhesion of these bacteria was tested on five hydrocarbons of different hydrophobicities. E. coli, the weakest biofilm producer, and with the highest surface energy and lowest hydrophobicity amongst the bacteria compared in the study, had the lowest load on all fibres. Scanning electron microscopy revealed non-uniform binding of gram-negative and gram-positive bacteria. Nanoroughness of fibres favored bacterial adhesion. The study showed correlation between surface properties and adherence of bacteria on fibres, with the results being of direct significance to medical and hospitality sectors.Electronic supplementary materialThe online version of this article (10.1007/s12088-020-00903-5) contains supplementary material, which is available to authorized users.     

Potential role of cytokinin–auxin synergism, antioxidant enzymes activities and appraisal of genetic stability in Dianthus caryophyllus L.—an important cut flower crop

The regeneration potential, antioxidative enzyme activities, and genetic stability among micropropagated plantlets of Dianthus caryophyllus L. were evaluated. Multiple adventitious shoots were induced from leaf explants on Murashige and Skoog medium incorporated with various combinations and concentrations of plant growth regulators (PGRs). The highest leaf explant response (90%), number of shoots per explant (15.30?±?1.19), and shoot length (6.75?±?0.63 cm) was recorded in response to a combination of 2.5 μM 6-benzyladenine and 0.5 μM α-naphthaleneacetic acid (NAA) after 8 wks culture. Subsequent subculturing for five passages, on a medium with the same composition of PGRs, induced the highest shoot number (42.50?±?1.44), with an average shoot length of 8.06 cm after the fourth subculture. Different concentrations of indole-3-butyric acid (IBA) were tested to determine the optimum conditions for ex vitro rooting of microshoots. The best result was accomplished with a pulse treatment of IBA (100 μM) applied to the basal end of the microshoot for 30 min, followed by transfer to plastic cups containing soilrite, and eventually established in natural soil with an 85% survival rate. The determination of activities of antioxidative enzymes (superoxide dismutase, ascorbate peroxidase, catalase, and glutathione reductase) revealed involvement of these enzymes in shoot differentiation and development. All of these activities were interlinked with each other and played significant roles in the scavenging of toxic free radicals. Intersimple sequence repeat DNA analysis was carried out using five primers. The amplification products were monomorphic in micropropagated plants, similar to those of the mother plant. No polymorphisms were detected revealing the genetic integrity of the micropropagated plants.     

A triglucoside of hecogenin from fruits of Agave cantala

The fruits of Agave cantala contain a steroidal saponin which is a glycoside of hecogenin with three molecules of glucose. Its structure has been e