Sequence polymorphisms in a phytoplasma underlie organ proliferation in maize

Maize bushy stunt phytoplasma (MBSP) is a vector-borne pathogen that induces multiple morphological alterations in maize plants. Orlovskis et al. find that MBSP isolates from two maize growing regions of Southeast Brazil differ in strengths of disease symptom induction, including lateral branching.

Maize bushy stunt phytoplasma (MBSP) induced diverse morphological changes in maize plants.
Maize bushy stunt phytoplasma (MBSP) induced diverse morphological changes in maize plants. (A) Infected plants demonstrate lateral branching and ear proliferation. (B) Plant stunting is a common symptom in infected maize (MBSP-infected plant on the right, non-inoculated control on the left). (C) Leaf rip (marginal tearing indicated by the white arrow). (D) Infected leaves curl (twist) and develop necrotic tissue at the tip. (E) Young leaves remain closed in the whorl and do not fully expand. (F) Young leaves (arrow) at the plant tip show characteristic chlorosis which is usually absent in older basipetal leaves. (G) Leaf reddening. (H) Leaf yellowing. (I) Necrotic lesions on the leaf blade. Pictures were taken 3 weeks after the inoculation with MBSP.

Whole genome sequencing of the MBSP isolates identified 86 polymorphic sites, of which 45% are located in protein-coding regions. Nine polymorphisms associate with lateral branching symptoms, one of which locates in a lipoprotein-encoding effector gene and two in a lipoprotein transporter. Surprisingly, other effector genes were conserved among the isolates, including an MBSP isolate from Mexico.

This paper is part of the Annals of Botany Special Issue on Plant Immunity. It will be free access till June 2017 and after April 2018.

Written by Annals of Botany Office

The Annals of Botany Office is based at the University of Oxford.

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