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Robledo J, Welker S, Shtein I, Bernardini C, Vincent C, Levy A. Phloem and Xylem Responses Are Both Implicated in Huanglongbing Tolerance of Sugar Belle. PHYTOPATHOLOGY 2024; 114:441-453. [PMID: 37551959 DOI: 10.1094/phyto-05-23-0148-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
Although huanglongbing (HLB) is a devastating citrus disease, improved tolerant cultivars, such as Sugar Belle (SB) mandarin, have been identified. To understand the responses that HLB-affected SB undergoes, we compared 14CO2 fixation, carbohydrate export, phloem callose accumulation, relative expression of plant defense activators, and anatomical changes between healthy and infected SB trees versus susceptible Pineapple (PA) sweet orange. Eight- to ten-week-old leaves of infected SB showed a 2.5-fold increase in 14CO2 fixation and a 13% decrease in 14C-carbohydrate export, whereas HLB-affected PA presented a decrease of 33 and 50%, respectively. The mean distance of a callose deposit to its closest neighbor was 36% smaller in infected SB versus healthy, whereas in HLB-affected PA, it was 33% higher. Expression of papain-like cysteine proteases (PLCPs) was upregulated in SB but downregulated in PA. Infected SB showed minor alterations in the number of xylem vessels, a 16% larger xylem vessel lumen area, and a 14% increase in the proportional area of the xylem. In contrast, PA showed a 2.4-fold increase in the xylem vessel number and a 2% increase in the proportional xylem area. Three complementary mechanisms of tolerance in SB are hypothesized: (i) increased carbohydrate availability induced by greater CO2 fixation, mild effect in carbohydrate export, and local accumulation of callose in the phloem; (ii) activation of defense response via upregulation of PLCPs, and (iii) increased investment in the xylem structure. Thus, phloem and xylem modifications seem to be involved in SB tolerance.
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Affiliation(s)
- Jacobo Robledo
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
| | - Stacy Welker
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Ilana Shtein
- Eastern Region Research and Development Center, Ariel, Israel
| | - Chiara Bernardini
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Christopher Vincent
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Amit Levy
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, U.S.A
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Chen Q, Min A, Luo S, He J, Wu R, Lin X, Wang Y, He W, Zhang Y, Lin Y, Li M, Zhang Y, Luo Y, Tang H, Wang X. Metabolomic Analysis Revealed Distinct Physiological Responses of Leaves and Roots to Huanglongbing in a Citrus Rootstock. Int J Mol Sci 2022; 23:ijms23169242. [PMID: 36012507 PMCID: PMC9409271 DOI: 10.3390/ijms23169242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 08/14/2022] [Accepted: 08/15/2022] [Indexed: 12/11/2022] Open
Abstract
Huanglongbing (HLB) is an obstinate disease in the citrus industry. No resistant citrus resources were currently available, but various degrees of Huanglongbing tolerance exist in different germplasm. Citrus junos is emerging as one of the popular rootstocks widely used in the citrus production. However, its responses to the HLB causal agent, Candidatus Liberibacter asiaticus (CLas), were still elusive. In the current study, we investigated the physiological, anatomical, and metabolomic responses of a C. junos rootstock ‘Pujiang Xiangcheng’ by a controlled CLas grafting inoculation. The summer flushes and roots were impaired at 15 weeks after inoculation, although typical leaf symptomatic phenotypes were not obvious. The chlorophyll pigments and the photosynthetic rate were compromised. The phloem sieve tubes were still working, despite the fact that the callose was deposited and the starch granules were accumulated in the phloem cells. A wide, targeted metabolomic analysis was carried out to explore the systematic alterations of the metabolites at this early stage of infection in the leaves and root system. The differentially accumulated metabolites in the CLas-affected leaves and roots compared with the mock-inoculation control tissues revealed that distinct responses were obvious. Besides the commonly observed alteration of sugar and amino acids, the active break down of starch in the roots was discovered. The different types of fatty acids were altered in the two tissues, with a more pronounced content decline in the roots. Our results not only provided fundamental knowledge about the response of the C. junos rootstock to the HLB disease, but also presented new insights into the host–pathogen interaction in the early stages.
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Affiliation(s)
- Qing Chen
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Ailing Min
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Shu Luo
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Jinwei He
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Runqin Wu
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Ximeng Lin
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Yan Wang
- Institute of Pomology and Olericulture, Sichuan Agricultural Universtiy, Chengdu 611130, China
| | - Wen He
- Institute of Pomology and Olericulture, Sichuan Agricultural Universtiy, Chengdu 611130, China
| | - Yunting Zhang
- Institute of Pomology and Olericulture, Sichuan Agricultural Universtiy, Chengdu 611130, China
| | - Yuanxiu Lin
- Institute of Pomology and Olericulture, Sichuan Agricultural Universtiy, Chengdu 611130, China
| | - Mengyao Li
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Yong Zhang
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Ya Luo
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
| | - Haoru Tang
- Institute of Pomology and Olericulture, Sichuan Agricultural Universtiy, Chengdu 611130, China
- Correspondence: (H.T.); (X.W.)
| | - Xiaorong Wang
- Institute of Pomology and Olericulture, Sichuan Agricultural Universtiy, Chengdu 611130, China
- Correspondence: (H.T.); (X.W.)
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Srivastava AK, Das AK, Jagannadham PTK, Bora P, Ansari FA, Bhate R. Bioprospecting Microbiome for Soil and Plant Health Management Amidst Huanglongbing Threat in Citrus: A Review. FRONTIERS IN PLANT SCIENCE 2022; 13:858842. [PMID: 35557712 PMCID: PMC9088001 DOI: 10.3389/fpls.2022.858842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 03/21/2022] [Indexed: 06/15/2023]
Abstract
Microorganisms have dynamic and complex interactions with their hosts. Diverse microbial communities residing near, on, and within the plants, called phytobiome, are an essential part of plant health and productivity. Exploiting citrus-associated microbiomes represents a scientific approach toward sustained and environment-friendly module of citrus production, though periodically exposed to several threats, with Huanglongbing (HLB) predominantly being most influential. Exploring the composition and function of the citrus microbiome, and possible microbial redesigning under HLB disease pressure has sparked renewed interest in recent times. A concise account of various achievements in understanding the citrus-associated microbiome, in various niche environments viz., rhizosphere, phyllosphere, endosphere, and core microbiota alongside their functional attributes has been thoroughly reviewed and presented. Efforts were also made to analyze the actual role of the citrus microbiome in soil fertility and resilience, interaction with and suppression of invading pathogens along with native microbial communities and their consequences thereupon. Despite the desired potential of the citrus microbiota to counter different pathogenic diseases, utilizing the citrus microbiome for beneficial applications at the field level is yet to be translated as a commercial product. We anticipate that advancement in multiomics technologies, high-throughput sequencing and culturing, genome editing tools, artificial intelligence, and microbial consortia will provide some exciting avenues for citrus microbiome research and microbial manipulation to improve the health and productivity of citrus plants.
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Affiliation(s)
- Anoop Kumar Srivastava
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
| | - Ashis Kumar Das
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
| | | | - Popy Bora
- Department of Plant Pathology, Assam Agricultural University, Jorhat, India
| | - Firoz Ahmad Ansari
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
| | - Ruchi Bhate
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
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