INVESTIGATIONS ON PEACH YELLOW LEAF ROLL (PYLR) PHYTOPLASMA IN PRUNUS PERSICA L. BATSCH
Loading...
Date
2023-11-21
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
UHF,NAUNI
Abstract
ABSTRACT
Peach, Prunus persica (L.) Batsch, a member of Rosaceae family is highly remunerative fruit crop. However,
infection ofinfection roll (PYLR) phytoplasma causes huge yield losses and continues to impact its production in
sub-tropical areas of Himachal Pradesh. Extensive surveys were conducted during 3 cropping season 2020, 2021 and 2022 in
50 orchards located in Solan and Sirmour districts of Himachal Pradesh. The surveys revealed the prevalence of typical
characteristic symptoms consisting of diffused chlorosis followed by yellowing, downward rolling, red spotting, reddening,
enlarged swollen midrib and lateral veins giving a tattered and tuft appearance. Based on these symptoms, maximum
incidence of 86.66 per cent was recorded at Bhat Ka Siana in Sirmour district and 12 per cent at Experimental Farm of Fruit
Science, Dr YSP UHF, Nauni in Solan district where as minimum incidence was recorded at Karyut with 0.66 per cent and
Dharo Ki Dhar with 2.50 per cent in both the districts, respectively. On the contrary, orchards located at Sanora, Nerikotli,
Gaura, Jatoli, Deothi, Matnali (Orchard no. 3), Kulath (Orchard no. 2) and Phagu (Orchard no. 1 and 3) were completely free
from the disease as none of the peach plantations exhibited typical symptoms of PYLR phytoplasma. Susceptible peach
cultivars namely July Elberta, Redhaven, Sunhaven and Giant Elberta were examined through histological detection by
DAPI based fluorescent microscopy and revealed the presence of distinctive bluish white phytoplasma fluorescence in
phloem sieve tube elements indicating the association of phytoplasma. Biological indexing of peach yellow leaf roll (PYLR)
phytoplasma was carried out by dodder and two budding techniques (chip- budding and T- budding). Transmission of PYLR
phytoplasma using Cuscuta reflexa was unable to form strong dodder bridge whereas 80 per cent transmission rate was
recorded in chip- budding compared to T- budding (40 per cent) and chip- budding was therefore observed to be the best
method for early detection of peach yellow leaf roll (PYLR) phytoplasma. Host range of peach yellow leaf roll (PYLR)
phytoplasma was determined in commercial stone fruits on the basis of symptoms development and using fluorescent
microscopy. Almond cultivars namely Nonpareil and Drake tested positive besides peach cvs. July Elberta, Redhaven,
Sunhaven and Giant Elberta. On the basis of histological and molecular identification, Prunus domestica, Toona ciliata,
Erigeron annus and Ageratum conyzoides were found to act as potential alternate/reservoir hosts of peach yellow leaf roll
(PYLR) phytoplasma. Molecular characterization of peach yellow leaf roll (PYLR) phytoplasma was done using nested PCR
assay yielding an amplicons of ̴221 bp and amplified PCR product was subjected for sequencing. The obtained 16S rRNA
nucleotide sequence was submitted to NCBI Gene Bank database and accession no OQ200125 was granted. Phylogenetic
analysis revealed 100 per cent similarity with Chinese strain (Phragmites australis witches’-broom phytoplasma strain
SHZPA1). Subsequently, eleven peach cultivars growing at Nauni area were subjected to germplasm screening in which two
peach cultivars namely Redhaven and July Elberta were found susceptible for peach yellow leaf roll (PYLR) phytoplasma