Examination of host responses of different citrus varieties and - - PowerPoint PPT Presentation

▶
examination of host responses of different citrus
SMART_READER_LITE
LIVE PREVIEW

Examination of host responses of different citrus varieties and - - PowerPoint PPT Presentation

May 07, 2023 454 likes •725 views

Examination of host responses of different citrus varieties and relatives to HLB infection Bill Dawson, Svetlana Y. Folimonova, Cecile J. Robertson, and Stephen M. Garnsey University of Florida, Citrus Research and Education Center Lake Alfred, FL

slide-1
SLIDE 1

Examination of host responses of different citrus varieties and relatives to HLB infection Bill Dawson, Svetlana Y. Folimonova, Cecile J. Robertson, and Stephen M. Garnsey

University of Florida, Citrus Research and Education Center Lake Alfred, FL

slide-2
SLIDE 2

HLB host range

Greenhouse Greenhouse experiments

under under ‘select agent’ diti conditions

slide-3
SLIDE 3

Main objectives in this study:

1) Examine different citrus genotypes or citrus relatives with the purpose of understanding at the whole plant level how different citrus varieties respond to Las, and whether there are resistant or tolerant varieties. 2) Understand whether there is a correlation between severity of disease and the level of bacterial concentration 3) Examine how Las is distributed in infected plant, and where through out the infected host the bacterium is present at the highest concentration 4) Determine how environmental conditions affect symptoms 4) Determine how environmental conditions affect symptoms development

slide-4
SLIDE 4

Citrus varieties and relatives that have been screened

  • 1

Citrus macrophylla (Alemow)

  • 17

Sour orange

  • 2

Valencia Sweet orange

  • 3

Ruby Red grapefruit

  • 4

Nules clementine (mandarin)

  • 5

Minneola tangelo

  • 18

Meiwa kumquat

  • 19

Calamondin

  • 20

Citrus hystrix

  • 21

Swingle citrumelo

  • 5

Minneola tangelo

  • 6

Eureka lemon

  • 7

Volkamer lemon

  • 8

Persian lime

  • 21

Swingle citrumelo

  • 22

Sun Chu Sha (mandarin)

  • 23

Palestine Sweet lime

  • 24

Citrus latipes 8 Persian lime

  • 9

Mexican lime

  • 10

Citron

  • 11

Carrizo citrange 24 Citrus latipes

  • 25

Cleopatra mandarin

  • 26

Madam vinous Sweet Orange

  • 27

Duncan grapefruit g

  • 12

Poncirus trifoliata

  • 13

Citrus halimii

  • 14

Citrus indica g p

  • 28

Ling Ping Yau pummelo

  • 29

Hirado Buntan Pink pummelo

  • 30

Siamese Sweet pummelo

  • 15

Citrus micrantha

  • 16

Citrus ambyllocarpa

  • 31

Severinia buxifolia

slide-5
SLIDE 5

We have not found citrus varieties or relatives that are resistant to infection by Candidatus that are resistant to infection by Candidatus Liberibacter asiaticus. However, there were major differences in host response between different varieties. response between different varieties.

slide-6
SLIDE 6

Different citrus varieties have different degrees of susceptibility to HLB

Eureka lemon Duncan grapefruit Cleopatra mandarin

slide-7
SLIDE 7

Nules clementine: high sensitivity to HLB

Healthy l

6 months upon inoculation

plants HLB‐infected

6 months upon inoculation

plants

3 months upon inoculation

slide-8
SLIDE 8

Effect of HLB on Madam Vinous sweet orange

(9 months after inoculation) ( )

Healthy Healthy Infected

slide-9
SLIDE 9

Symptoms produced by different citrus varieties under greenhouse conditions

Eureka lemon Duncan grapefruit Hirado Buntan pink pummelo Madam Vinous sweet orange Mexican lime

slide-10
SLIDE 10

Response of different citrus genotypes to HLB under greenhouse conditions

Citrus or relative Las titer

Symptoms description

g

relative

Poncirus trifoliata + Extreme tolerance

some stunting

trifoliata

some stunting

Carrizo citrange + Extreme tolerance

little or no chlorosis little or no chlorosis

Eureka lemon ++ Extreme tolerance

chlorosis only under high light

Persian lime +++ Extreme tolerance

no distinct symptoms no distinct symptoms

slide-11
SLIDE 11

Sun Chu Cha +++

Tolerant: scattered

groups of chlorotic leaves

S +++

Tolerant

Sour orange +++

Tolerant

Volkamer lemon +++

Tolerant

  • C. macrophylla

+++

Tolerant

Swingle citrumelo +++

Tolerant

Citron ++

Tolerant

Citron ++

Palestine sweet lime

+++

Tolerant

Mexican lime +++

Tolerant

Calamondin +++

Tolerant

Calamondin +++

  • C. micantra

+++

Tolerant

slide-12
SLIDE 12

Siamese sweet pummelo

++ Intermediate:

chlorotic leaves, some th d ti growth reduction

Ling Ping Yau pummelo

++ Intermediate

Hirado Buntan pink pummelo

++ Intermediate

  • C. ambyllocarpa

+++ Intermediate

Cleopatra mandarin

+++ Intermediate

  • C. indica

++ Intermediate

Meiwa kumquat

++ Intermediate

slide-13
SLIDE 13

Valencia sweet

  • range

+++ Sensitive: chlorosis

including tip, reduced growth growth

Madam Vinous sweet

  • range

+++ Sensitive ‐ same

Duncan grapefruit

++ Sensitive ‐ same

Ruby Red grapefruit

++ Sensitive ‐ same

Citrus halimii

++ Sensitive: chlorosis,

vein corking, death

Nules clementine

++ Sensitive: strong

chlorosis, reduced growth, death

Minneola tangelo

++ Sensitive: strong

chlorosis, reduced growth

slide-14
SLIDE 14

Ct = 22

Cleopatra mandarin

Ct = undet Ct = undet

Liberibacter

  • ften is unevenly

Ct = 21

distributed in infected trees

Ct = undet

slide-15
SLIDE 15

Ct=25 C 22

Citrus macrophylla

Ct=22 Ct=undet Ct=23

slide-16
SLIDE 16

Disease Symptoms Are Correlated with Abnormal Sugar Distribution Abnormal Sugar Distribution Phloem blockage (phloem necrosis, callose Phloem blockage (phloem necrosis, callose deposits) Disruption of sugar movement pathway – lack of sugar export lack of sugar export Starch granules accumulate and disrupt g p chloroplasts Chlorotic symptoms on leaves

slide-17
SLIDE 17

Effect of light on HLB symptoms development

H H I I G i th G d Grown in the greenhouse Grown under 24h light

slide-18
SLIDE 18

Severity of symptoms increases when plants are incubated under continuous light

Eureka lemon

h d h l h h Greenhouse conditions 24 hours light growth room

slide-19
SLIDE 19

Symptoms in greenhouse Symptoms under continuous light

Sour

  • range

Cleopatra mandarin

slide-20
SLIDE 20

SCS mandarin Eureka lemon Nules clementine

Typical light room symptoms

SCS mandarin Cleopatra mandarin

MV sweet orange MV sweet orange

MV sweet orange

slide-21
SLIDE 21

Non‐inoculated sweet orange plants of 5 different cultivars

Hamlin Pineapple Madam Vinous Hamlin Pineapple Madam Vinous Rohde Red Valencia Valencia 1-18-31

slide-22
SLIDE 22

HLB – infected sweet oranges

( in greenhouse) ( g )

H li Pi l M d Vi Hamlin Pineapple Madam Vinous Rohde Red Valencia Valencia 1-18-31

Healthy Hamlin

slide-23
SLIDE 23

Effect of HLB on grapefruit (in greenhouse)

Healthy Infected Healthy Infected

Marsh grapefruit Rio Red Grapefruit

slide-24
SLIDE 24

Healthy plants HLB‐infected plants

Marsh Grapefruit Rio Red Grapefruit

slide-25
SLIDE 25

Summary:

1 Susceptibility to Las

  • 1. Susceptibility to Las:

Although Las was able to multiply in all tested citrus genotypes, there was a range of responses in different varieties from extreme tolerance to high sensitivity to HLB infection.

2 Distribution of Las within a tree:

  • 2. Distribution of Las within a tree:

In a particular plant higher titers are often associated with symptomatic areas.

  • 3. Las titer and severity of disease:

Wh diff t it t d th i l When different citrus genotypes are compared, there is no clear correlation between bacterial titer and severity of disease.

  • 4. Light intensity and duration greatly affect symptoms

development.

slide-26
SLIDE 26

Important questions:

What makes some citrus hosts tolerant and others – sensitive to HLB infection? sensitive to HLB infection? Can plants be modified to become resistant or tolerant?