Abstract
Peppers, a worldwide crop, are threatened by different pathogens. Powdery mildew, a biotroph fungal infection, can cause several damages directly on vegetative parts and indirectly on fruits. Despite some sources of resistance have been described, commercial genotypes only with partial resistance have been developed due to the complex nature of such resistance and variable genetic expression, which depends on the stage of the plants. In this paper 49 accessions from different Capsicum species and origins have been tested. Plants were grown in growth chambers inside of mini greenhouses. Repeated inoculations under pepper leaves were applied by spraying a suspension of 104 conidia ml-1. Readings were made at 30 and 60 days after inoculation (DAI). Total number of leaves (TL), total number of affected leaves (LA), and maximum area affected (MAA) in the most damaged leaf were scored. In addition, a composite infection index (CII) was calculated on the basis of the three mentioned traits. Inoculated plants showed more severe symptoms at 30 DAI than at 60 DAI. Different response patterns were observed: from accessions suffering high leaf shedding to some others with local hypersensitive response, indicating different gene action. The use of CII prevented species bias and disease response. In the present work, four highly tolerant accessions were identified, including two chiltepins, C. annuum wild relatives, Ag-01 and Ag-02, and two C. annuum A-06 and A-23.
Highlights
Peppers (Capsicum spp.) are one of the most important horticultural crops grown worldwide and adapted to a range of growing conditions, which are used as both fresh or processed (FAOSTAT, 2021)
First screening The first trial infection produced the characteristic damage of powdery mildew (PM) in the plants
Some accessions like A-06, Ag-01 and Ag-02 evolved with very low values of LA, LA/Total number of leaves (TL) ratio, maximum area affected (MAA) and composite infection index (CII), C-02 showed moderate values in both 30 and 60 DAP, and C-03 and B-10 continued with high disease values (Table 2)
Summary
Peppers (Capsicum spp.) are one of the most important horticultural crops grown worldwide and adapted to a range of growing conditions, which are used as both fresh or processed (FAOSTAT, 2021). As a widespread crop it is threaten by different pathogens. Powdery mildew (Leveillula taurica (Lév.) Arn.) is one of them, mainly in cool and humid environments, as greenhouses and open fields in mid-latitudes during autumn. Received in revised form: 03 Jun 2021. From Volume 49, Issue 1, 2021, Notulae Botanicae Horti Agrobotanici Cluj-Napoca journal uses article numbers in place of the traditional method of continuous pagination through the volume. The journal will continue to appear quarterly, as before, with four annual numbers
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