Meet the editors

Muhammad Sarwar Khan is a distinguished Plant Molecular Biologist and started his career as a Batchelor and Master's student in horticulture. He earned his Ph.D. from the University of Cambridge, UK. Dr. Khan was awarded a prestigious fellowship to research at the Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, by the Rockefeller Foundation. He has served as the founding Head of the Biotech

Interdisciplinary Division at the NIBGE and is currently serving as the Director of the Center of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, Pakistan. Dr. Khan has supervised more than 100 Ph.D. candidates, MPhil students, and researchers. He has published several papers in high-impact journals, including *Nature and Nature Biotechnology*, and is the author of several book chapters and books. Dr. Khan has received several prestigious awards, including the President's Medal for Technology, a Gold Medal in Agriculture from the Pakistan Academy of Sciences, a Performance Gold Medal, the Biotechnologist Award by the National Commission of Biotechnology, and the Best University Teacher Award by the Higher Education Commission of Pakistan. He is a fellow of the Cambridge Commonwealth Society, the Cambridge Philosophical Society, the Rockefeller Foundation, and the Cochran Foundation. He is also a member of the Pakistan Botanical Society and the International Association for Plant Biotechnology.

Iqrar Ahmad Khan is a horticulturist/botanist by profession. Dr. Khan has a distinguished career spanning more than forty years. He is a graduate of the University of Agriculture, Faisalabad, Pakistan, and the University of California, Riverside, USA. He has supervised more than seventy graduate students including fourteen PhDs. His students and research associates have achieved significant positions in academia and industry. He has

undertaken forty-four research projects and published 375 articles and books. He served as vice-chancellor of two universities for more than nine years and founded five new universities and district campuses (2008–2017). He has also established several national and international research centers and institutes, including a Chinese Confucius Institute and a Bio-Energy Institute. He was COP/Director US-Pak Center of Advanced Studies (2017–2019) and Ela Bhatt Professor at the University of Kassel, Germany (2020). His research on wheat, potato, citrus, mango, and dates has benefitted the industry and significantly improved the life and livelihood of farmers and rural communities. He is a Distinguished National Professor and a Fellow of the Pakistan Academy of Sciences. He was awarded Sitara-e-Imtiaz for his services by the President of Pakistan and *Ordre des Palmes Academiques* by the French Government for his international contribution to education.

Contents

**Section 1**

**Section 2**

*and Rachid Lahlali*

*and Ashara Sajid*

**Preface III**

Citrus Genealogy, Classification, and Biotechnology **1**

**Chapter 1 3**

**Chapter 2 15**

**Chapter 3 39**

Citrus Biotic and Abiotic Stress Management **61**

**Chapter 4 63**

**Chapter 5 79**

**Chapter 6 105**

**Chapter 7 135**

*by Jagveer Singh, Vishal Sharma, Kuldeep Pandey, Shahnawaz Ahmed,* 

Citrus Biotechnology: Current Innovations and Future Prospects *by Ghulam Mustafa, Muhammad Usman, Faiz Ahmad Joyia* 

Integrated Management Approach to Citrus Fungal Diseases by Optimizing Cocoa-Based Agroforests Structural Characteristics

A Current Overview of Two Viroids Prevailing in Citrus Orchards:

*by Zineb Belabess, Nabil Radouane, Tourya Sagouti, Abdessalem Tahiri* 

*by Yasir Iftikhar, Muhammad Zeeshan Majeed, Ganesan Vadamalai* 

*by Ndo Eunice Golda Danièle and Akoutou Mvondo Etienne*

Citrus Exocortis Viroid and Hop Stunt Viroid

Indexing Virus and Virus-Like Diseases of Citrus

*Xanthomonas citri* ssp. *citri* Pathogenicity, a Review

*by Juan Carlos Caicedo and Sonia Villamizar*

Introductory Chapter: Citrus for a Healthy Life

Horticultural Classification of Citrus Cultivars

*Manveen Kaur and Gurupkar Singh Sidhu*

*by Muhammad Sarwar Khan*

*and Muhammad Sarwar Khan*

## Contents



Preface

Citrus is a nutrient-rich fruit crop, predominantly cultivated in tropical and subtropical regions of the world. The *Citrus* genus belongs to the Rutaceae family and consists of a variable number of species due to the admixture of wide morphological diversity, intra- and interspecific sexual compatibility, apomixis, and spontaneous mutations. Citrus fruits are highly nutritious and beneficial for health due to the presence of bioactive compounds that have antioxidant, antitumor, antiinflammatory, and blood clot-inhibiting characteristics. However, citrus production and quality are challenged with several biotic and abiotic problems. Conventional research has played a pivotal role in the improvement of citrus and the introduction of novel biotechnological approaches reduces the time involved in the development of varieties and fixes problems where traditional approaches have failed. Further, transgenic technology and omics approaches have great potential to improve this

*Citrus - Research, Development and Biotechnology* consists of fourteen chapters that are divided into three sections. Section I, "Citrus Genealogy, Classification, and Biotechnology", consists of Chapters 1 through 3. In Chapter 1, Dr. Khan highlights citrus genealogy, production, and crop management. Further, it demonstrates the nutritional and nutraceutical importance of citrus and the biotechnology interventions to improve citrus. In Chapter 2, Dr. Sindhu et al. examine the horticultural classification of *Citrus* cultivars and the sexual and asexual means through which these varieties have been evolved. In Chapter 3, Dr. Khan et al. describe the milestones achieved in citrus improvement employing conventional approaches as well

Section II, "Citrus Biotic and Abiotic Stress Management", consists of Chapters 4 through 8. In Chapter 4, Drs. Daniele and Etienne explain the importance of weather conditions in cropping systems and substantiate how pathogen and disease spreading is managed through the structural features of the cocoa-based agroforestry system (CBAFS) in the humid forest zones of Cameroon. In Chapter 5, Dr. Lahlali et al. describe two prevailing viroids—Citrus Exocortis Viroid (CEVd) and Hop Stunt Viroid (HSVd)—and stress the use of transcriptomic and proteomic approaches to fully analyze and understand the mechanisms of host-pathogen interactions. In Chapter 6, Dr. Iftikhar et al. highlight that the indexing of diseases caused by a virus and virus-like pathogens is essential for producing disease-free citrus nurseries. Further, they briefly describe the commonly used biological, serological, and molecular tests for the detection of citrus viruses and virus-like pathogens. In Chapter 7, Drs. Caicedo and Villamizar review the main structural and functional features of bacterial responsible for spreading disease and causing symptoms in a susceptible host, including bacterial attachment, antagonism, effector production, quorum sensing regulation, and genetic plasticity at phenotypical and genotypical levels. In Chapter 8, Dr. Naqvi et al. explain the effects of changing climate on citrus and highlight how agronomic, breeding, and biotechnological interventions can mitigate climate change effects on citrus.

fruit crop and address biotic as well as abiotic problems.

as the achievements made through biotechnology interventions.

*by Ersin Demir, Hülya Silah and Nida Aydogdu*
