Strategy and impact of developing improved potato varieties for Sichuan

Bing Li (18735424247@163.com), Jianjun Hu, Mingxia Tang, Kexiu Wang and Wei He; Crop Research Institute (CRI) of Sichuan Academy of Agricultural Sciences, Chengdu China.

Background

Both Sichuan’s potato production area and total yield remain among the largest in China. The annual potato planting and annual fresh potato supply are characterized by the province’s unique geographic features, which has good economic and social benefits. In the low altitude area represented by Chengdu Plains ( 500 masl), new potato varieties with high yield, yellow skin and flesh, and mid-early maturity are cultivated. Winter cultivation is with November planting and harvesting in March to May. The autumn cultivation is with September planting and harvesting in December to January. In the middle-high altitude Penzhou mountain area (1000-1500 masl), medium-late varieties with high yield, good quality, good disease and stress resistance are planted, which are planted from January to March, harvested from June to August. In the Sichuan Plateau area (3000-3500 masl), ethnic minorities cultivate late maturing varieties with high yield and starch content, good disease resistance, strong cold and drought resistance and wide adaptability. Seeds are sown from March to April and harvested from September to October. Late blight is one of the most important diseases in potato production in Sichuan. Breeding new varieties with broad spectrum resistance to late blight is the most effective guarantee for potato production in mid to high altitude areas of Sichuan Province.

Breeding strategy

1. CRI has the germplasm bank for Sichuan Province and maintains germplasm resources introduced by foreign research institutions such as International Potato Center (CIP), Argentina（INTA, Scotland（JHI, Belgium, Vietnam, Canada, Institute of Vegetables and Flowers of Chinese Academy of Agricultural Sciences, Qinghai Academy of Agricultural Sciences, Huasong Seed Industry Co., Ltd. and local varieties of Sichuan Province. Evaluating the germplasm for different characteristics including high yield, good quality, disease and stress resistance laid a good foundation for selecting varieties suitable for the different ecological regions of Sichuan.
2. Based on the unique three-dimensional climate in Sichuan, shuttle breeding at high and low altitudes was adopted. This permits the rapid selection of clones and improve breeding efficiency in the 3 different ecological areas (Figures 1, 2 and 3 below).
3. Many germplasm resources introduced from the CIP have strong resistance to late blight, providing excellent parental materials for the breeding of new varieties resistant to disease and stress in middle and high-altitude areas; The early maturing varieties introduced from the Chinese Academy of Agricultural Sciences have good adaptability in the Chengdu plain and are very popular in the market. Cooperation with Huasong seed Industry has led to successful breeding of new early maturing potato varieties.
4. Using gene editing technology to edit homeopathic regulatory elements to accurately improve the special important phenotype of potato. We have already obtained some new disease resistant germplasms through gene editing technology.

Public and Private Partners

Potato program of Crop Research Institute of Sichuan Academy of Agricultural Sciences (CRI）has long been engaged in the creation of new materials for potato breeding, new method innovation, new variety breeding, cultivation physiology research, integration of green and efficient cultivation technology and the use of aeroponics potato production system for improved seed breeding. In the process of breeding new potato varieties in Sichuan, based on the production status and social needs of different ecological regions, we set up hybrid breeding nursery and seed potato breeding base in low altitude area and middle and high altitude area respectively, and selected high-yield, good potato type and fresh early potato varieties in low altitude area with Chengdu Plain as the core area. The new potato varieties with high yield, high quality (high starch content, good taste), late blight resistance, strong drought and cold resistance , strong adaptability were selected in the middle and high altitude area. The unique climatic conditions and geographical environment of the West Sichuan Plateau, such as fertile soil, long sunshine time and large temperature difference between day and night, are conducive to potato flowering and fruit. In the West Sichuan Plateau, we set up a greenhouse of 100 square meters, planted the core backbone parents, formulated the hybrid combinations according to the breeding objectives, and carried out the screening and evaluation of the hybrid combinations in the west Sichuan Plateau and Chengdu Plain to cultivate new varieties suitable for different ecological regions. In addition, we also carry out joint breeding with relevant research units at home and abroad, and introduce their hybrid combinations according to breeding objectives, and conduct screening evaluation on the western Sichuan Plateau and Chengdu Plain.

Public and Private Partners
From 1985, Dr. Peter VanderZaag began to conduct cooperative research with China on behalf of CIP. From 2010 to 2024, he came to Sichuan for many times to guide the CRI. He gave on-site technical guidance and academic exchanges on potato research and development and made important contributions to the research on potato breeding and resources of CIP. In the application of international cooperation projects, he also gave great encouragement and support. Based on the regional climate characteristics and character needs, a large number of processing special varieties and potato hybrid combination seeds have been introduced into CRI, which greatly promoted the development of Sichuan potato industry.

Dalat Potato, Vegetables and Flowers Research Center with the support of Dr Pham Xuan Tung, a potato breeder who has access to a large collection of CIP germplasm for late blight and virus resistance and adaptation to climate change and processing qualities. Hybrid crosses were obtained for evaluation in The CRI program.

CRI has been working closely with Sichuan Normal University for a long time to carry out research on the mechanism of potato disease resistance and stress resistance, using gene editing technology to improve the potato varieties selected by CRI (such as Chuanyu 50) and create more and better new varieties suitable for different ecological regions in Sichuan. At the same time, the evaluation, demonstration and promotion of these new varieties are carried out through the cooperation with the agricultural science and technology institutes in the main planting areas in Sichuan Province.

Results

Potato program of CRI has long cooperated with domestic and foreign research institutions (International Potato Center, Argentina, Scotland, Netherlands, Belgium, Vietnam, Chinese Academy of Agricultural Sciences, Huasong Seed Industry Co., LTD.), engaged in the introduction, screening and evaluation of potato germplasm resources. CRI maintains the Sichuan Provincial Genebank with excellent germplasm resources from China and abroad. In the past few decades, the ecological advantages of high and low altitudes and shuttle breeding methods in Sichuan have been used to carry out the selection and breeding of a large number of new potato varieties with high yield, high quality, disease resistance and stress resistance have been released. The released varieties include Chuanyu117, Chuanyu 50, Chuanyu 85, Chuanyu 62, Chuanyu 65 which are all widely grown (Table 1). These new varieties were bred from the seeds of hybrid combinations introduced by CIP. T50 was bred from parents 392634.52 and 392626.9 from CIP and was registered as a new non-major crop variety by the Department of Agriculture in 2019. The variety has high resistance to late blight and virus disease, strong cold and drought resistance, high yield, high dry matter and high starch, and wide adaptability. At present, this variety has been widely popularized in Chengdu plain and plateau mountainous areas, helping farmers increase their income and rural revitalization.

In the past ten years, the CRI has collected and evaluated local germplasm resources in the whole province, and preserved and registered a number of excellent local varieties that meet the dietary habits of local people. These were freed of all pathogens through meristem culture, accurately identification and registered.

Table 1. Varieties released by CRI. All numbered parents are from CIP. Katadin is from the USA.

Variety name	female	male	Major attributes
Chuanyu117	65-ZA-5	DTO-28	Moderate resistance to potato late blight and virus disease, high yield, adaptation wide, middle early maturing.
Chuanyu50	392634.52	392626.9	High resistance to potato late blight and virus disease, cold and drought resistance, high yield, high dry matter and high starch content, adaptation wide, late maturing
Chuanyu85	392634.5Din	2392626.9	High resistance to potato late blight and virus disease, high yield, high dry matter, adaptation wide, middle early maturing.
Chuanyu62	393280.58	391679.7	Moderate resistance to potato late blight and virus disease, high yield, strong self-compatibility, late maturing.
Chuanyu65	393085.5	Katadin	Moderate resistance to potato late blight, resistance to potato virus disease, late maturing.

 

Lessons Learned

International exchanges and cooperation with relevant research institutions abroad and nationally, promoted the introduction, screening and evaluation of excellent germplasm resources, enriched the genebank, and identify a group of excellent parental materials.
Accelerate the accurate identification of excellent materials and related gene mining, laying a foundation for the creation of new materials by molecular marker-assisted breeding and gene editing.

Improve breeding methods, increase breeding efficiency, make good use of backbone parent materials, and speed up the cultivation of breakthrough disease resistance and resistance of high yield and high quality new varieties.

The diverse topography, geomorphology environment characteristics in Sichuan along with the different ethnic, diet and farming culture differences makes for a challenging and interesting experience in developing new varieties for each of the 3 zones in Sichuan.