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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #302907
Title: Differences in stylet sheath occurrence and the fibrous ring (sclerenchyma) between xCitroncirus plants relatively resistant or susceptible to adults of the Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae)

Author
item Ammar, Eldesouky
item Richardson, Matthew
item Abdo, Zaid
item Hall, David
item Shatters, Robert - Bob

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2014
Publication Date: 10/24/2014
Citation: Ammar, E., Richardson, M.L., Abdo, Z., Hall, D.G., Shatters, R.G. 2014. Differences in stylet sheath occurrence and the fibrous ring (sclerenchyma) between xCitroncirus plants relatively resistant or susceptible to adults of the Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae). PLoS One. doi: 10.1371/PO.2014-0110919.

Interpretive Summary: The Asian citrus psyllid (ACP) transmits the phloem-limited bacteria associated with huanglongbing (HLB), the world’s most serious disease of citrus. Host plant resistance may provide an environmentally safe and sustainable method of controlling ACP and/or HLB. Two xCitroncirus accessions (hybrids of Poncirus trifoliata and Citrus spp.), that are relatively resistant or susceptible to ACP adults, were compared in relation to ACP feeding behavior and some structural features of the leaf midrib. Fewer ACP stylet sheaths (feeding tracks) were formed in the midrib, and fewer of these sheaths reached the vascular bundle, in the resistant compared to the susceptible accessions. Also, the fibrous ring around the phloem was significantly wider (thicker) in resistant than in susceptible accession. Our data indicate that feeding and/or probing by ACP adults in the vascular bundle is less frequent in resistant than in susceptible plants, and suggest that the thickness of the fibrous ring may be a barrier to stylet penetration into the vascular bundle. These results may help in the development of citrus plants resistant to ACP, which in turn can probably halt or slow the spread of HLB bacteria by this important psyllid vector.

Technical Abstract: The Asian citrus psyllid (ACP, Diaphorina citri, Hemiptera: Liviidae), is the principal vector of the phloem-limited bacteria strongly associated with huanglongbing (HLB), the world's most serious disease of citrus. Host plant resistance may provide an environmentally safe and sustainable method of controlling ACP and/or HLB. Two xCitroncirus accessions (hybrids of Poncirus trifoliata and Citrus spp.), that are relatively resistant (UN-3881) or relatively susceptible (Troyer-1459) to ACP adults with regard to adult longevity, were compared in relation to ACP feeding behavior and some structural features of the leaf midrib. The settling (putative feeding) sites of ACP adults on various parts of the leaf were not influenced primarily by plant accession. However,fewer ACP stylet sheaths were formed in the midrib and fewer stylet sheath termini reached the vascular bundle (phloem and/or xylem) in UN-3881 compared to Troyer-1459 plants. Furthermore, in midribs of UN-3881 leaves the fibrous ring (sclerenchyma) around the phloem was significantly wider (thicker) compared to that in midribs of Troyer-1459 leaves. Our data indicate that feeding and/or probing by ACP adults into the vascular bundle is less frequent in the more resistant (UN-3881) than in the more susceptible (Troyer-1459) accessions. Our results also suggest that the thickness of the fibrous ring may be a barrier to stylet penetration into the vascular bundle, which is important for successful ACP feeding on the phloem and for transmitting HLB-associated bacteria. These results may help in the development of citrus plants resistant to ACP, which in turn could halt or slow the spread of the HLB associated bacteria by this vector.