ZINC-MICROELEMENT OF REFERENCE IN APPLE NUTRITION
This paper aims to present the risk of being exposed apple trees to zinc deficiency, within an bifactorial experience with fertilizers. Mobile Zn content in soil, on one hand and total zinc content in plant material (leaves) on the other hand, as mobile phosphates content in soil, represents agrochemical indices for assessing the probability of zinc deficiency. These indices determined during two years of experimentation, can be quantified in two synthetic indicators IRPM mobile phosphates reaction index in soil, used for chernozems, that express and explain the influence of pH and available phosphorus content (P-AL ppm) on Zn mobility in soil and its availability to plants; and ICZn zinc deficiency index, which takes into consideration the value of mobile Zn content in soil, being more significant in order to predict the probability of zinc deficiency appearance. Folowing the fertilization of experimental variants, we analyzed the data obtained during two consecutive years of experience, and noticed that available phosphorus content in soil increased gradually, while mobile Zn, although increasing quantity, it lies within suboptimal limits. Together these values and soil pH, which has the tendency to rise up to 8.00, the two indices calculated ICZn and IRPM, clearly indicates that the probability of deficiency in zinc appearance is medium to large, ICZn take values between 1.39 and 3.13, while IRPM take values between 0.117 and 0.232.
Zinc deficiency up-regulates expression of high-affinity phosphate transporter genes in both phosphate-sufficient and -deficient barley roots.
Phosphate (P) is taken up by plants through high-affinity P transporter proteins embedded in the plasma membrane of certain cell types in plant roots. Expression of the genes that encode these transporters responds to the P status of the plants, and their transcription is normally tightly controlled. However, this tight control of P uptake is lost under Zn deficiency, leading to very high accumulation of P in plants. We examined the effect of plant Zn status on the expression of the genes encoding the HVPT1 and HVPT2 high-affinity P transporters in barley (Hordeum vulgare L. cv Weeah) roots. The results show that the expression of these genes is intimately linked to the Zn status of the plants. Zn deficiency induced the expression of genes encoding these P transporters in plants grown in either P-sufficient or -deficient conditions. Moreover, the role of Zn in the regulation of these genes is specific in that it cannot be replaced by manganese (a divalent cation similar to Zn). It appears that Zn plays a specific role in the signal transduction pathway responsible for the regulation of genes encoding high-affinity P transporters in plant roots. The significance of Zn involvement in the regulation of genes involved in P uptake is discussed.
Genetics of the phenotypic evolution in sheep: a molecular look at diversity-driving genes
Background After domestication, the evolution of phenotypically-varied sheep breeds has generated rich biodiversity. This wide phenotypic variation arises as a result of hidden genomic changes that range from a single nucleotide to several thousands of nucleotides. Thus, it is of interest and significance to reveal and understand the genomic changes underlying the phenotypic variation of sheep breeds in order to drive selection towards economically important traits. Review Various traits contribute to the emergence of variation in sheep phenotypic characteristics, including coat color, horns, tail, wool, ears, udder, vertebrae, among others. The genes that determine most of these phenotypic traits have been investigated, which has generated knowledge regarding the genetic determinism of several agriculturally-relevant traits in sheep. In this review, we discuss the genomic knowledge that has emerged in the past few decades regarding the phenotypic traits in sheep, and our ultimate aim is to encourage its practical application in sheep breeding. In addition, in order to expand the current understanding of the sheep genome, we shed light on research gaps that require further investigation. Conclusions Although significant research efforts have been conducted in the past few decades, several aspects of the sheep genome remain unexplored. For the full utilization of the current knowledge of the sheep genome, a wide practical application is still required in order to boost sheep productive performance and contribute to the generation of improved sheep breeds. The accumulated knowledge on the sheep genome will help advance and strengthen sheep breeding programs to face future challenges in the sector, such as climate change, global human population growth, and the increasing demand for products of animal origin.