Priming is an Effective Defence Mechanism in Plants to Fight Pests: Says Study

In response, researchers from the Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, and Tata Institute of Fundamental Research have provided strong molecular evidence for the two-fold advantage of defence 'priming' as a sustainable crop protection strategy in the native spice crop 'Black Pepper' (Piper Nigrum).

Priming is a mechanism that allows plants to boost their natural defence mechanisms after exposure to biotic or abiotic stress. Black Pepper is a globally important woody spice crop, but diseases and pests pose serious constraints to its sustainable yield. The major pathogen constraint responsible for the disastrous 'quick wilt' or 'foot rot' disease is Phytophthora capsica, which infects the stem, leaves, and roots of cuttings in the nursery and pepper plantations. The current systematic fungicide treatment measures have negative impacts and can lead to phytotoxicity and fungicide resistance.

The researchers explain that their study reports, for the first time, the capability of defence priming as an efficient crop protection strategy in Piper nigrum against infection by Phytophthora capsici. The data also establish a proof-of-concept of the capability of defence priming through stem/vine infection in safeguarding Piper nigrum from infection in nurseries and plantations. The study opens the way for in-depth mechanistic studies to identify new capabilities of natural agents that can prime the defence of Piper nigrum sustainably, enhancing crop protection with the associated enhancement in Piperine biosynthesis. This is the first report offering strong molecular evidence for the two-fold benefits of defence priming in Piper nigrum.

Impacts of Glycol Chitosan Treatment:

Glycol Chitosan (GC) which has been used in this study is a water-soluble, non-toxic polymer with various commercial and possible biomedical uses. Researchers report also says that it is known to persuade plant defence and was uniformly observed that GC treatment provides protection from the brutality of ‘quick wilt’ disease and caused a notable delay in the appearance of symptoms. A noteworthy observation of the study was the significant increase in ‘Piperine’ accumulation in leaves due to priming. Piperine is regarded as majorly responsible for the strong taste of black pepper.

The Group also conducted studies in rooted cuttings in seedlings and fields and detached leaves of mature plants. They also injected GC into the experimental plant’s leaves and post 24 hours of treatment, subjected them to pathogen infection. The Evolvement of symptoms and disease spread was examined microscopically and confirmed by molecular pathogen DNA quantification analysis. The expression levels of critical genes of the defence signalling pathway were calculated along with Lignin and Piperine content quantification.

Researchers recommended that the study has displayed the promising capability of ‘priming’ and has capable implications in crop nurseries and the field. More work is needed to attain the durability of priming and to boost the process and timing of treatment for large-scale commercial implementation.

The study has been published in Frontiers and the study team comprised M Indu, Manjula Sakuntala, B Meera, KC Sivakumar, K Mohammed Shafi, B Nagarathnam, Chidambareswaren Mahadevan, and Ramanathan Sowdhamini.