Resistance of peanut to web blotch caused by Phoma arachidicola is related to papillae formation and the hypersensitive response

Abstract

Peanut (Arachis hypogaea) is an important economic crop that is susceptible to various foliar diseases. Web blotch, which is caused by Phoma arachidicola, is one of the most serious peanut foliar diseases because it affects the leaves and results in substantial yield losses. In this study, the P. arachidicola infection process and the response of peanut plants to infection were revealed through a cytological study of resistant and susceptible peanut varieties. Conidial germination rates, appressorium formation and resistance responses, including papillae formation and the hypersensitive response (HR), were analysed at different infection stages. Notably, the basal infection response of susceptible varieties resulted in limited papillae formation and a single HR, which was followed by programmed cell death. The papillae formation frequency and HR frequency were significantly greater in the resistant varieties than in the susceptible varieties at 84 h postinoculation. The primary difference between the two resistant varieties was the superior HR of Zheng8903 compared with that of Yuhua15. The complex amphidiploid peanut genome may explain the complexity and diversity of the resistance responses. The interactions of functional orthologs should be clarified and perhaps modulated in future investigations. The results of this study revealed the differences in the resistance responses among peanut germplasm and may be relevant for the breeding of new peanut varieties highly resistant to P. arachidicola.

Cytological and transcriptomic analysis to unveil the mechanism of web blotch resistance in Peanut

“…1 ), indicating that the number of papillae and the extent of HR at the infection site are important factors associated with web blotch resistance. These results are consistent with those of previous studies that determined the presence of papillae indicates PTI has been activated (first layer of defense) and HR indicates that ETI has been activated (second layer of defense) [ 30 ]. In the current study, 48 hpi seemed to be the dividing line between PTI and ETI.…”

“…Resistant variety Zheng8903 (ZH) and susceptible variety PI343384 (PI) were grown in a growth chamber at 25 °C with a 14-h light (8,000 lx)/10-h dark cycle and 60–90% humidity at the Henan Academy of Agricultural Sciences. When seedlings reached the 6- to 8-leaf stage, they were sprayed with a YY187 spore suspension (2 × 10 6 conidia/ml) supplemented with 0.1% Tween 20 [ 78 ], after which the parietal leaves were labeled with a string. Next, the relative humidity in the growth chamber was adjusted to 85%, but the other conditions were unchanged.…”

Calcium enhanced the resistance against Phoma arachidicola by improving cell membrane stability and regulating reactive oxygen species metabolism in peanut

“…However, various biotic and abiotic stresses affect peanut yield, with pests and diseases being among the major factors causing yield reduction [3]. Peanut is susceptible to a multitude of pathogens, with common diseases including peanut black spot, peanut early leaf spot, and peanut web blotch, the latter being the most severe and caused by Phoma arachidicola Marasas Pauer&Boerema [4]. Peanut web blotch primarily occurs during the mid to late stages of peanut growth, especially during the pod-setting and maturing phases, leading to significant defoliation and yield losses.…”