The potato is an important crop for food, vegetable and industrial use, and is widely cultivated and consumed. However, potato cultivation and yield are affected by a variety of factors, including biotic and abiotic stresses. The impact of these factors can cause serious economic losses in potato-producing areas. Studying the stress resistance mechanism of potato can help to understand the adaptability and physiological mechanism of plants under stress conditions, which can ensure food supply, reduce economic losses, and provide scientific support for the development of sustainable agriculture. Recently, the potato team of Huazhong Agricultural University published a paper entitled "StHAB1, a negative regulatory factor in abscisic acid signaling, plays crucial roles in" in the Journal of Experimental Botany, Plant Cell and Environment and The plant Journal potato drought tolerance and shoot branching”、“ScAREB4 promotes potato constitutive and acclimated freezing tolerance associated with enhancing trehalose synthesis and oxidative stress tolerance" and "StMLP1, as a Kunitz trypsin inhibitor, enhances potato resistance and specifically expresses in vascular bundles duringRalstonia solanacearuminfection", The research progress of the research team on the stress resistance mechanism of potato was reported. Abscisic acid (ABA) plays a very important role in the process of drought resistance and growth and development of plants. PP2C is a key enzyme in the ABA signaling pathway. Class A PP2C plays a negative role as a regulator in ABA signaling pathway and plant stress resistance. However, the function of class A PP2C in potatoes is poorly understood. The researchers studied the function of StHAB1, a potato class A PP2C gene, in potatoes. StHAB1 has no tissue expression specificity, but is strongly induced by ABA and drought. Knockdown of StHAB1 made potatoes more sensitive to ABA and more drought tolerant. In contrast, the overexpression of StHAB1 in the functionally acquired mutant StHAB1G276D reduced the sensitivity and drought tolerance of plants to ABA. The researchers found that StHAB1 interacts with all ABA receptor PYLs and with StOST1, a family of SnRKs that regulates stomatal opening and closing. StHAB1 regulated the drought resistance of potatoes by interacting with StOST1 to regulate the opening of stomata. Both knockdown of StHAB1 and overexpression of StHAB1G276D altered potato plant morphology (Figure 1). It is worth noting that the overexpression of StHAB1G276D led to more branching in potatoes, and RNA-seq sequencing of sampling at the branches showed that auxin offloading proteins StPIN3, StPIN5 and StPIN8 were induced in the axillary buds of plants overexpressing StHAB1G276D. At the same time, auxin (IAA) content decreased significantly in the axillary buds of excess plants. However, there was no significant change in the expression of StBRC1a, a key gene that regulates branching in potato, in transgenic plants, indicating that StHAB1G276D was independent of StBRC1a in regulating potato branching. These findings suggest that StHAB1 plays a very important role in regulating drought resistance and branching in potato.
Figure 1. Phenotypic statistics of StHAB1 drought resistance and plant axillary buds
Low temperature frost is the main environmental factor restricting potato production. Abscisic acid (ABA) can enhance frost tolerance in many plant species, but strong evidence of ABA-mediated signaling pathways associated with frost tolerance is still lacking. In this study, the cold acclimation ability of potato genotype was enhanced with the increase of endogenous content of ABA. Further exogenous administration of ABA and its inhibitor (NDGA) can enhance and decrease the freezing tolerance of potatoes, respectively. In addition, the expression patterns of genes downstream of the ABA signaling pathway were analyzed, and it was found that only ScAREB4 was found to be effective in S. commersonii (CMM5). The transgenic lines overexpressed by ScAREB4 showed stronger constitutive and cold acclimation resistance. Transcriptome analysis showed that overexpression of ScAREB4 induced the expression of TPS9 (trehalose 6-phosphate synthase) and GSTU8 (glutathione transferase), which was consistent with an increase in TPS activity, trehalose content, GST activity, and a significant reduction in accumulated H2O2 in the ScAREB4 overexpressing transgenic lines (Figure 2). In conclusion, the results of this study showed that the increase of endogenous content of ABA was related to the frost tolerance of potato. In addition, ScAREB4, as a downstream transcription factor for ABA signaling, improves the freeze resistance of potatoes, which is associated with increased trehalose content and antioxidant capacity. This study enriches the role of ABA in plant frost resistance and provides theoretical guidance for potato cold resistance breeding.
Figure 2. A hypothetical model of AREB4 modulating cryoresistance under cold stress
For the mining of genes associated with bacterial wilt resistance in potatoes, the team identified a Miraculin-like protein StMLP1, which belongs to the Kunitz trypsin inhibitor family. It was found that the expression level of StMLP1 gradually increased during the infection of R. solanacearum bacteria. Analysis and identification of the promoter revealed that the promoter of StMLP1 was a tissue-specific promoter that was both inducible in response to R. solanacearum infection and specifically expressed in vascular bundles (Fig. 3). In addition, StMLP1 exhibits trypsin inhibitor activity, and its signal peptide is essential for the function of the StMLP1 protein to function in proper localization. For the study of StMLP1 resistance, the team found that overexpression of StMLP1 in potatoes could enhance resistance to R. solanacear, but inhibiting the expression of StMLP1 during R. solanacearum infection accelerated the infection of R. solanacearum to a certain extent. RNA-seq analysis showed that StMLP1 had a certain regulatory effect on potato immunity. In this study, the function of StMLP1 was systematically identified, and the inducible and tissue-specific promoters with good application prospects were excavated, enriching the theoretical basis for potato immune regulation.
Figure 3. Promoter-inducible and tissue-specific identification of StMLP1
The study published in the Journal of Experimental Botany, with Dr. Tengfei Liu and graduate Master Liepeng Dong as the first authors, and Professor Botao Song as the corresponding authors. The study published in the journal Plant Cell and Environment, doctoral student Tiantian Liu is the first author, and Professor Botao Song is the corresponding author. In the study published in The plant Journal, Dr. Bingsen Wang and graduate Master Yuqi Wang are the co-first authors, and Prof. Huilan Chen and Prof. Botao Song are the co-corresponding authors of the paper.
The series of studies were published by the National Key Laboratory of Germplasm Innovation and Utilization of Fruit and Vegetable Horticulture/Key Laboratory of Potato Biology and Biotechnology of the Ministry of Agriculture and Rural Affairs, and were supported by the National Natural Science Foundation of China (31871683, 32101781, 32201789), the Modern Agricultural Industry Technology Research System (CARS-09), and the Guangdong Provincial Key Area R&D Program (2022B0202060001).
The potato team of Huazhong Agricultural University is the supporting unit of provincial and ministerial research platforms such as the Key Laboratory of Potato Biology and Biotechnology of the Ministry of Agriculture and Rural Affairs and the Hubei Potato Engineering Technology Research Center, and is also an important part of the National Key Laboratory of Germplasm Innovation and Utilization of Fruit and Vegetable Horticulture and the Central China Branch of the National Vegetable Improvement Center. The team has 7 in-service teachers, including 3 professors, 3 associate professors, 1 senior agronomist, 6 postdoctoral fellows, and more than 60 doctoral and master's students participating in the research project.
After more than 20 years of efforts, the research fields of potato germplasm resource innovation, functional genomics of important traits, genetic breeding, seed potato breeding and agricultural machinery agronomic integration have been formed. The team collected and preserved more than 2,000 copies of various resources such as wild potato seeds, cultivated varieties and interspecific hybrids. The system completed the identification of resistance to late blight, bacterial wilt and virus disease of potato resources, and the evaluation of cold resistance and quality traits. A protoplast fusion technology platform has been established, and the first batch of bacterial wilt resistant and cold-resistant interspecific somatic cell hybrids have been obtained, creating a number of parental materials with outstanding resistance and extensive genetic background. The molecular and genetic mechanisms of tuber development, low-temperature saccharification and cold resistance were analyzed, the genetic basis of plant resistance formation and the molecular mechanism of plant-pathogen interaction such as late blight, bacterial wilt and viral diseases were revealed, and the corresponding molecular marker-assisted selection system was established, which provided theoretical support and technical platform for resistance improvement and breeding technology innovation. The molecular physiological mechanism of tuber development was proposed, the efficient production technology of test-tube potato was invented, and the seed potato breeding system was innovated. The mechanized cultivation technology of "deep furrow, wide ridge and full mulching" of southern potato was established. He has bred 22 new varieties, obtained 5 new plant variety rights, won more than 20 national invention patents, won the first prize of Hubei Provincial Science and Technology Progress Award, the first prize of Hubei Provincial Technological Invention Award, the first prize of the National Agriculture, Animal Husbandry and Fishery Harvest Award of the Ministry of Agriculture, and published more than 300 academic papers.
Article Links:
https://doi.org/10.1093/jxb/erad292
https://doi.org/10.1111/pce.14707
https://doi.org/10.1111/tpj.16428
Original link: https://mp.weixin.qq.com/s/D8y9j-VJMgis2ldDiNvhug
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