Abid Riaz

Stripe rust analysis of D-genome synthetic wheats (2n = 6x = 42, AABBDD) and their molecular diversity

Stripe or yellow rust caused by Puccinia striiformis f. sp. tritici is a threat to many of the existing cultivars of Pakistan. Many attempts are being made to evolve new varieties resistant to stripe rust to reduce the losses caused by this disease. For this purpose, novel genes are needed to incorporate into the existing cultivars. These genes are found in the wild progenitors of wheat that are D-genome donors to wheat. As a result of extensive research, wheat synthetic hexaploids have been developed. These synthetics have resistances against biotic as well as abiotic stresses including the yellow rust. A group of such synthetics has been identified which seems resistant to this destructive disease. This group was tested under field conditions to identify resistance against stripe rust. The same population was analysed at molecular level to explore the genetic diversity for rust resistance. Genetic diversity among 34 selected synthetic hexaploid wheats was studied by random amplified polymorphic DNA (RAPD) analysis. A set of 12 RAPD primers was applied, and the level of polymorphism was found to be 46.67%. The coefficients in the range of 71–100% were detected by genetic similarity matrix based on Nei and Lis index. These coefficients were used for constructing a dendrogram using unweighted pair group of arithmetic means. Synthetic hexaploid line 34 was found to exhibit maximum genetic distances among the 34 selected lines. The same accession also showed excellent phenotypic characters with above average grain weight. These synthetic hexaploids carrying genetic potential for stripe rust resistance and morphological traits should be useful for improvement of existing wheat cultivars.

First Report of pre-harvest fruit rot of strawberry caused by Botrytis cinerea in Khyber Pakhtunkhwa (KPK) province & Islamabad (Pakistan)

Strawberry (Fragaria × ananassa Duch.) is an emerging fruit crop in Pakistan, cultivated on approximately 1500 hectares. A survey was conducted during each crop season viz. 2014-2015 and 2015-2016 in geographically important strawberry growing regions of Khyber Pakhtunkhwa and Islamabad . Fruit rot was observed in all surveyed fields that indicates 100 % prevalence of the disease in the study area . Affected tissue was covered with a thin layer of grayish white to dark gray mycelium, which later became fuzzy due to profusion of conidiophores, and rot enveloped the entire fruit. Rotted fruit gradually dried, becoming hard and mummified. Fruit tissue segments at the margins of lesions on infected fruit were cut into 3- to 5 mm2 pieces, surface disinfected with 2% sodium hypochlorite for 1 min, rinsed by washing three times in sterile distilled water, and blotted dry. Disinfected segments were placed on Czapek-Dox (CZ) agar and incubated at 25 ± 2°C. Grayish colonies were observed 3 to 5 days later. Colonies...

First report of strawberry leaf spot caused by Alternaria alternata in Pakistan

Strawberry (Fragaria × ananassa Duch.) has recently become an economically important fruit crop in Pakistan and is cultivated on approximately 1500 ha. A survey across Punjab, Khyber Pakhtunkhwa (KPK) provinces and Islamabad (Islamabad Capital territory) was conducted during March and April of 2015-2016 growing season revealed black leaf spot symptoms on strawberry leaves. Leaf spots were irregular in shape, 3 to 6 mm in diameter, and blackish brown. Disease incidence was found 17 to 55 % in visited fields. Portions of symptomatic leaf tissue (3 × 5 mm) were excised from the margins of lesions; surface disinfected with 2% sodium hypochlorite for 2 min, rinsed three times in sterile distilled water (SDW) and blotted dry. Leaf tissue was then placed on Czapek Dox agar (CDA) and incubated at 25 ± 2°C with a 12-h photoperiod for 3 to 6 days. Morphology of the 78 isolates was examined; colonies were initially white, then turned light to dark brown and greyish black and produced abundant aerial hyphae. Conidiop...