Plant hormones (Literature sources on phytohormones and plant signalling)

Source: Agroscope Newsletter (15.02.2024)

Excerpts: "Agroscope has been granted approval by the Federal Office for the Environment for a field trial with spring barley. The focus is on a barley gene that has been disabled by new breeding techniques. The trial, which will be launched in spring 2024 on the Protected Site in Zurich-Reckenholz and will run for three years, aims to determine whether yields can be increased in this manner. The CKX2 gene is involved in the regulation of seed formation. Disabling this gene by means of a new breeding methods (CRISPR/Cas9 genome editing) brings about increased yields in rice and oilseed rape (see, below, ‘From rice to barley’).

"From rice to barley - Crop yield formation is complex and involves many different genes. However, Japanese researchers have discovered that the mutation of the CKX2 gene in rice has an unexpectedly significant effect on yield. Results were so convincing that they are now used in rice breeding. Research results show that genes corresponding to the CKX2 gene from rice also play a role e.g. in oilseed-rape yield formation. Therefore, it is reasonable to study this effect in further crops. In the best-case scenario, at the end of these trials on the Protected Site it will be possible to issue a recommendation as to whether breeders should disable one or both CKX2 genes in order to boost yields. What is certain, however, is that important information will be provided on the function of the CKX2 genes in barley – and hence further pieces of the puzzle will be available for a better understanding of yield formation."

Authors: Sayanti Mandal, Mimosa Ghorai, Uttpal Anand, Debleena Roy, Nishi Kant, Tulika Mishra, Abhijit Bhagwan Mane, Niraj Kumar Jha, Milan Kumar Lal, Rahul Kumar Tiwari, Manoj Kumar, Radha, Arabinda Ghosh, Rahul Bhattacharjee, Jarosław Proćków and Abhijit Dey.

Frontiers in Genetics (2022)

Abstract: "Over the last decade, remarkable progress has been made in our understanding the phytohormones, cytokinin’s (CKs) biosynthesis, perception, and signalling pathways. Additionally, it became apparent that interfering with any of these steps has a significant effect on all stages of plant growth and development. As a result of their complex regulatory and cross-talk interactions with other hormones and signalling networks, they influence and control a wide range of biological activities, from cellular to organismal levels. In agriculture, CKs are extensively used for yield improvement and management because of their wide-ranging effects on plant growth, development and physiology. One of the primary targets in this regard is cytokinin oxidase/dehydrogenase (CKO/CKX), which is encoded by CKX gene, which catalyses the irreversible degradation of cytokinin. The previous studies on various agronomically important crops indicated that plant breeders have targeted CKX directly. In recent years, prokaryotic clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system has been increasingly used in editing the CKO/CKX gene and phenomenal results have been achieved. This review provides an updated information on the applications of CRISPR-based gene-editing tools in manipulating cytokinin metabolism at the genetic level for yield improvement. Furthermore, we summarized the current developments of RNP-mediated DNA/transgene-free genomic editing of plants which would broaden the application of this technology. The current review will advance our understanding of cytokinins and their role in sustainably increase crop production through CRISPR/Cas genome editing tool."