The present study involves the use of host induced gene silencing (HIGS) approach to achieve resistance to late blight in Indian potato cultivars ‘Kufri Pukhraj’ and ‘Kufri Chipsona 1’ by silencing the cellulose synthase A (CesA) gene(s) of Phytophthora infestans. Based on the sequence differences in the N terminal region of the CesA gene of P. infestans and potato, two RNAi constructs namely PiCesA3-RNAi construct I and PiCesA2-RNAi construct II, were prepared targeting CesA genes of P. infestans. The modified RNAi vector containing the RNAi constructs were mobilised into Agrobacterium strain LBA4404, and the latter was used for the genetic transformation of both the cultivars of potato. The putative transformants were multiplied and maintained on MS1 medium (basal MS + 10 µM AgNO3) for further analysis. The PCR analysis of the transformed shoots confirmed the presence of respective ~ 200 bp sense, antisense fragments, and 750 bp npt-II gene specific fragment. Subsequently, the confirmed transgenics plants of both the cultivars expressing dsRNA-specific to RNAi construct I and II were tested for their resistance against late blight by detached leaf and whole plant assays. The detached leaf assay showed that the infected leaves of transgenic lines of both the cultivars expressing both the RNAi constructs showed lesser lesion diameter compared to the leaves of the wild-type plants. The whole plant assay also showed significantly lower disease incidence (DI) and disease severity (DS) indices in transgenic lines than in control plants. In cv ‘Kufri Pukhraj’, transgenic line 4 expressing dsRNA-specific to PiCesA3-RNAi construct I, the DI 50% and DS 38.88% was observed whereas in transgenic line 4 expressing dsRNA-specific to PiCesA2-RNAi construct II showed DI 43.75% and DS 30.55%, which is the lowest disease incidence and severity. In cv ‘Kufri Chipsona 1’, line 3 expressing dsRNA-specific to PiCesA3-RNAi construct I showed DI 37.5% and DS 37.49%, and line 1 and 7 expressing dsRNA-specific to PiCesA2-RNAi construct II showed lowest disease incidence (43.75%) and disease severity (38.88%). The transgenic lines developed using PiCesA2-RNAi construct II showed higher level of resistance to late blight than those developed using PiCesA3-RNAi construct I. Among cultivars, the transgenic lines of cv. ‘Kufri Chipsona 1’ showed higher late blight resistance.

Host-mediated silencing of cellulose synthase gene of Phytophthora infestans for late blight resistance in Indian potato cultivars

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发表日期：

2025年11月18日

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Shivani Guleria,
Manchikatla Venkat Rajam,
Anil Kumar

摘要

The present study involves the use of host induced gene silencing (HIGS) approach to achieve resistance to late blight in Indian potato cultivars ‘Kufri Pukhraj’ and ‘Kufri Chipsona 1’ by silencing the cellulose synthase A (CesA) gene(s) of Phytophthora infestans. Based on the sequence differences in the N terminal region of the CesA gene of P. infestans and potato, two RNAi constructs namely PiCesA3-RNAi construct I and PiCesA2-RNAi construct II, were prepared targeting CesA genes of P. infestans. The modified RNAi vector containing the RNAi constructs were mobilised into Agrobacterium strain LBA4404, and the latter was used for the genetic transformation of both the cultivars of potato. The putative transformants were multiplied and maintained on MS1 medium (basal MS + 10 µM AgNO₃) for further analysis. The PCR analysis of the transformed shoots confirmed the presence of respective ~ 200 bp sense, antisense fragments, and 750 bp npt-II gene specific fragment. Subsequently, the confirmed transgenics plants of both the cultivars expressing dsRNA-specific to RNAi construct I and II were tested for their resistance against late blight by detached leaf and whole plant assays. The detached leaf assay showed that the infected leaves of transgenic lines of both the cultivars expressing both the RNAi constructs showed lesser lesion diameter compared to the leaves of the wild-type plants. The whole plant assay also showed significantly lower disease incidence (DI) and disease severity (DS) indices in transgenic lines than in control plants. In cv ‘Kufri Pukhraj’, transgenic line 4 expressing dsRNA-specific to PiCesA3-RNAi construct I, the DI 50% and DS 38.88% was observed whereas in transgenic line 4 expressing dsRNA-specific to PiCesA2-RNAi construct II showed DI 43.75% and DS 30.55%, which is the lowest disease incidence and severity. In cv ‘Kufri Chipsona 1’, line 3 expressing dsRNA-specific to PiCesA3-RNAi construct I showed DI 37.5% and DS 37.49%, and line 1 and 7 expressing dsRNA-specific to PiCesA2-RNAi construct II showed lowest disease incidence (43.75%) and disease severity (38.88%). The transgenic lines developed using PiCesA2-RNAi construct II showed higher level of resistance to late blight than those developed using PiCesA3-RNAi construct I. Among cultivars, the transgenic lines of cv. ‘Kufri Chipsona 1’ showed higher late blight resistance.