Beet curly top virus (BCTV) and beet curly top Iran virus (BCTIV) are known as the causal agents of curly top disease in beet and several other dicotyledonous plants in Iran. These viruses are transmitted by Circulifer species, and until now, there has been no confirmed report of their seed transmission. A percentage (38.2–78.0%) of the seedlings developed from the seeds of a petunia local cultivar under insect-free conditions showed stunting, interveinal chlorosis, leaf curling, and vein swelling symptoms, and were infected by BCTV when tested by PCR. Presence of BCTV in seed extracts of petunia local cultivar was confirmed by PCR and IC-PCR, followed by sequencing. Agroinoculation of curly top free petunia plants with a BCTV infectious clone resulted in BCTV infection of plants and their developed seeds. These results show the seed infection and transmission of BCTV in a local cultivar of petunia. Similar experiments performed with BCTIV showed that this virus is also seed transmissible in the same cultivar of petunia, although with a lower rate (8.8–18.5%). Seed transmission of curly top viruses may have significant implications in the epidemiology of these viruses.

Molecular mechanisms underlying phytoplasma interactions with host plants are largely unknown. In this study attempts were made to identify effectors of three phytoplasma strains related to 'Ca. P. aurantifolia', crotalaria phyllody (CrP), faba bean phyllody (FBP), and witches' broom disease of lime (WBDL), using information from draft genome of peanut witches' broom phytoplasma. Seven putative effectors were identified in WBDL genome (SAP11, SAP21, Eff64, Eff115, Eff197, Eff211 and EffSAP67), five (SAP11, SAP21, Eff64, Eff99 and Eff197) in CrP and two (SAP11, Eff64) in FBP. No homologs to Eff64, Eff197 and Eff211 in phytoplasmas of other phylogenetic groups were found. SAP11 and Eff64 homologs of 'Ca. P. aurantifolia' strains shared at least 95.9% identity and were detected in the three phytoplasmas, supporting their role within the group. Five of the putative effectors (SAP11, SAP21, Eff64, Eff115, and Eff99) were transcribed from total RNA extracts of periwinkle plants infected with these phytoplasmas. Transcription profiles of selected putative effectors of CrP, FBP and WBDL indicated that SAP11 transcripts were the most abundant in the three phytoplasmas. SAP21 transcript levels were comparable to those of SAP11 for CrP and not measurable for the other phytoplasmas. Eff64 had the lowest transcription level irrespective of sampling date and phytoplasma isolate. Eff115 transcript levels were the highest in WBDL infected plants. This work reports the first sequence information for 14 putative effectors in three strains related to 'Ca. P. aurantifolia', and offers novel insight into the transcription profile of five of them during infection of periwinkle.

Cotton leaf curl Multan betasatellite (CLCuMB) is responsible for symptom expression of a devastating disease of cotton in the Indian subcontinent. CLCuMB depends on helper virus replication-associated protein for its replication and on viral coat protein (CP) for its encapsidation. However, no direct evidence of encapsidation of CLCuMB in viral CP has been available. In the present study, non-viruliferous whiteflies were placed on tomato plants that had been agroinoculated with infectious clones of an Iranian isolate of tomato yellow leaf curl virus (TYLCV-[Ab]) and CLCuMB for an acquisition access period of 72 h and then transferred to healthy tomato seedlings at the 3- to 4-leaf stage. Typical symptoms of TYLCV-[Ab] appeared on inoculated seedlings 30-45 days post-inoculation. The presence of TYLCV-[Ab] and CLCuMB DNAs in symptomatic test plants and viruliferous whiteflies was confirmed by PCR analysis using specific primers and DIG Southern blotting. Furthermore, the possibility of CLCuMB DNA encapsidation in TYLCV-[Ab] CP within infected plants was examined by immunocapture PCR. The results showed that CLCuMB DNA was encapsidated in TYLCV-[Ab] CP. Whitefly-mediated transmission of CLCuMB in the presence of helper virus is additional evidence for encapsidation of CLCuMB by TYLCV-[Ab] CP.