Auxin efflux carriers, MiPINs, are involved in adventitious root formation of mango cotyledon segments

Effects of Naphthaleneacetic Acid, Indole-3-Butyric Acid and Zinc Sulfate on the Rooting and Growth of Mulberry Cuttings

The mulberry tree (Morus alba) is a perennial and fast-growing tree distributed worldwide under different climatic conditions. Most of the world’s silk production (>90%) is facilitated by the feeding of silkworm larvae on the leaves of mulberry (Morus alba L.) varieties. Therefore, exploration of the protocol for improving the propagation efficiency and increasing the reproductive capacity of M. alba varieties could be of great significance. This study aimed to determine the effect of four concentrations (0, 100, 200 and 400 mg L−1) each of naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), and zinc sulfate (0, 100 and 200 mg L−1), supplied separately or combined, on the rooting and growth of mulberry cuttings. M. alba cuttings were immersed for 5 s in each solution using the quick-dip method and subsequently, the cuttings were dried and planted in plastic pots and maintained in a greenhouse for 60 days. The number of leaves (NL), longest root size (LRS), longest stem size (LSS), number of rooted cuttings (NRC), number of stems per tree (NSP), rooting percentage (RP), wet root weight (WRW), dry root weight (DRW), wet stem weight (WSW), dry stem weight (DSW), wet leaf weight (WLW) and dry leaf weight (DLW) were evaluated. The results obtained showed an increase in all growth parameters of the mulberry cuttings. Treatments of hormones (IBA and NAA) and Zn sulfate were effective on LSS, LRS and WSW. The highest values of LSS were obtained for the treatments T5, T6, T14, T15, T16 and T18. Moreover, T5, T12 and T10 showed the highest values of LRS. The highest value of WSW was observed for T18, T5, T14, T15 and T16. The highest values of WLW and DLW were observed in T20 and T14. Dry stem weight (DSW) was high in T18 and T14. The application of NAA (at 200 mg L−1), IBA (200 and 400 mg L−1) and Zn sulfate (200 and 400 mg L−1), either alone or in double combination, can be a suitable and reliable method for mulberry propagation.

Expression Levels of Genes Encoding Proteins Involved in the Cell Wall-Plasma Membrane-Cytoskeleton Continuum Are Associated With the Maturation-Related Adventitious Rooting Competence of Pine Stem Cuttings

Stem cutting recalcitrance to adventitious root formation is a major limitation for the clonal propagation or micropropagation of elite genotypes of many forest tree species, especially at the adult stage of development. The interaction between the cell wall-plasma membrane and cytoskeleton may be involved in the maturation-related decline of adventitious root formation. Here, pine homologs of several genes encoding proteins involved in the cell wall-plasma membrane-cytoskeleton continuum were identified, and the expression levels of 70 selected genes belonging to the aforementioned group and four genes encoding auxin carrier proteins were analyzed during adventitious root formation in rooting-competent and non-competent cuttings of Pinus radiata. Variations in the expression levels of specific genes encoding cell wall components and cytoskeleton-related proteins were detected in rooting-competent and non-competent cuttings in response to wounding and auxin treatments. However, the major correlation of gene expression with competence for adventitious root formation was detected in a family of genes encoding proteins involved in sensing the cell wall and membrane disturbances, such as specific receptor-like kinases (RLKs) belonging to the lectin-type RLKs, wall-associated kinases, Catharanthus roseus RLK1-like kinases and leucine-rich repeat RLKs, as well as downstream regulators of the small guanosine triphosphate (GTP)-binding protein family. The expression of these genes was more affected by organ and age than by auxin and time of induction.