Effective Plant Ages for Screening for Field Resistance to Alternaria Leaf Spot (Caused by Alternaria spp.) under Natural Infection in Jerusalem artichoke (Helianthus tuberosus L.)

Wanalai Viriyasuthee,Ruey Shyang Chen,Suwita Saepaisan,Mark L Gleason,Sanun Jogloy,Weerasak Saksirirat

doi:10.3390/agronomy9110754

Abstract

Host plant resistance has proven to be effective for controlling Alternaria leaf spot on Jerusalem artichoke (JA), but efficient screening techniques have not been developed yet. The objective of this study is to estimate the relationship between disease resistance parameters of JA as a function of plant age. Six JA varieties and three plant ages at the time of inoculation (20, 40 and 60 days after transplanting) (DAT) are evaluated in a factorial experiment in randomized complete block design (RCBD) with four replications. Disease incidence (DI) and severity (DS) are estimated, from which area under the disease progress curve (AUDPC) was calculated. Disease parameters are positively and significantly correlated for plant ages of 40 and 60 DAT. Based on our results, screening of JA at 40 DAT for resistance to Alternaria leaf spot is recommended. Knowledge of the impact of plant age on resistance to key diseases can help breeders to accelerate breeding programs so superior genotypes can be identified before reproductive growth stages.

Highlights

Jerusalem artichoke (JA) is a tuber crop in the genus Helianthus that originated in temperate regions of North America [1].It is a good source of inulin, a sugar which is a linear mixture of oligosaccharides and polysaccharides [2].The tuber can be used as a raw material for health food products— for diabetics because inulin is not readily absorbed by humans—as well as in animal feed and bioethanol [3,4]
No difference in area under the disease progress curve (AUDPC) was found for AUDPC-Disease incidence (DI) and AUDPC-Disease severity (DS) (Table 1)
Significant differences between varieties and plant ages were observed for DI, DS, AUDPC-DI, and AUDPC-DS

Summary

Introduction

JA is a tuber crop in the genus Helianthus that originated in temperate regions of North America [1].It is a good source of inulin, a sugar which is a linear mixture of oligosaccharides and polysaccharides [2].The tuber can be used as a raw material for health food products— for diabetics because inulin is not readily absorbed by humans—as well as in animal feed and bioethanol [3,4]. JA is a tuber crop in the genus Helianthus that originated in temperate regions of North America [1]. It is a good source of inulin, a sugar which is a linear mixture of oligosaccharides and polysaccharides [2]. The production of JA in the tropic’s can be subject to severe the yield loss due to drought [6], stem rot [7] and Alternaria leaf spot [8]. Alternaria leaf spot is an emerging disease of JA in these regions. Alternaria leaf spot on JA appears as small yellow spots These grow into brown spots with yellow haloes. Defoliation of infected leaves begins on mature leaves and spreads upward

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