Preface

Studies involving *Arabidopsis thaliana* and other crop plants have continued to advance our knowledge of the mechanisms used by plants to survive in dynamic biotic and abiotic environments. Plants have adapted to diverse ecologies for ages; however, recent human migrations, agricultural activities, and climate change-induced phenomenon have forced plants to increasingly adapt to new environments. Furthermore, agricultural production is becoming increasingly vulnerable to climate variability and change characterized by altered frequency, timing, and magnitude of precipitation, temperature, and wind.

This book discusses morphological, anatomical, physiological, molecular, and genomic advances in plant defenses. It examines advances involving plant stress signaling mechanisms and molecular defense responses involving recently discovered biomolecules. It also discusses advances in gene expression changes, which can be inherited as described in epigenetic mechanisms and linked to observed phenotypic plant plasticity. The book also looks at emerging areas like plant growth-promoting microorganisms (PGPMs), which consist of a vast group of microorganisms found in the rhizosphere, on the root surface, or associated with it. It examines the mechanisms of action of PGPMs, including their ability to produce different plant growth regulators or phytohormones. Studies indicate that researchers have found intriguing plant interactions with their physical, microbial, and biotic environments. These interactions have been highlighted and linked to novel mechanisms, allowing us to understand deeper ways by which sessile plants have adapted and thriven in challenging environments.

The study examined issues on hailstorms and reports that to control secondary damage due to insect pests and diseases, the removal of fallen fruit to reduce the spread of disease and pests during their decay, large wounds on trunks and branches should be covered with a water-based paint to avoid desiccation and disease infection, then fruit thinning by removal of hail-damaged fruits are shown to improve the yield and quality of the remaining fruit. However, bud-breaking chemicals and growth/bio regulators may be applied to induce vegetative growth in the orchard crop along with fertilizers. In general, the major and chronic threats to ecosystem stability and sustainable agriculture are phytopathogenic microorganisms, the unlimited and regular use of chemical pesticides and fungicides could destroy soil ecology, degrade the fertility of the soil, and disrupt environment resulting in show harmful effects on human health and contaminating groundwater.

However, our studies found that PGPMs are environmentally friendly and offer a promising sustainable way of obtaining sustainable soil fertility and plant growth, although indirectly. Nevertheless, antibiotics production is considered one of the most powerful and studied biocontrol mechanisms of PGPMs against phytopathogens.

**Josphert Ngui Kimatu, BSc., Mphil., PGDE, Ph.D.** Professor, South Eastern Kenya University, School of Sciences and Computing, Department of Life Sciences, Kitui County, Kenya

**1**

Section 1

Mechanisms of Plant

Responses to Abiotic Stress

Section 1
